1 .. SPDX-License-Identifier: GPL-2.0
3 ===================================================================
4 The Definitive KVM (Kernel-based Virtual Machine) API Documentation
5 ===================================================================
10 The kvm API is a set of ioctls that are issued to control various aspects
11 of a virtual machine. The ioctls belong to the following classes:
13 - System ioctls: These query and set global attributes which affect the
14 whole kvm subsystem. In addition a system ioctl is used to create
17 - VM ioctls: These query and set attributes that affect an entire virtual
18 machine, for example memory layout. In addition a VM ioctl is used to
19 create virtual cpus (vcpus) and devices.
21 VM ioctls must be issued from the same process (address space) that was
22 used to create the VM.
24 - vcpu ioctls: These query and set attributes that control the operation
25 of a single virtual cpu.
27 vcpu ioctls should be issued from the same thread that was used to create
28 the vcpu, except for asynchronous vcpu ioctl that are marked as such in
29 the documentation. Otherwise, the first ioctl after switching threads
30 could see a performance impact.
32 - device ioctls: These query and set attributes that control the operation
35 device ioctls must be issued from the same process (address space) that
36 was used to create the VM.
41 The kvm API is centered around file descriptors. An initial
42 open("/dev/kvm") obtains a handle to the kvm subsystem; this handle
43 can be used to issue system ioctls. A KVM_CREATE_VM ioctl on this
44 handle will create a VM file descriptor which can be used to issue VM
45 ioctls. A KVM_CREATE_VCPU or KVM_CREATE_DEVICE ioctl on a VM fd will
46 create a virtual cpu or device and return a file descriptor pointing to
47 the new resource. Finally, ioctls on a vcpu or device fd can be used
48 to control the vcpu or device. For vcpus, this includes the important
49 task of actually running guest code.
51 In general file descriptors can be migrated among processes by means
52 of fork() and the SCM_RIGHTS facility of unix domain socket. These
53 kinds of tricks are explicitly not supported by kvm. While they will
54 not cause harm to the host, their actual behavior is not guaranteed by
55 the API. See "General description" for details on the ioctl usage
56 model that is supported by KVM.
58 It is important to note that althought VM ioctls may only be issued from
59 the process that created the VM, a VM's lifecycle is associated with its
60 file descriptor, not its creator (process). In other words, the VM and
61 its resources, *including the associated address space*, are not freed
62 until the last reference to the VM's file descriptor has been released.
63 For example, if fork() is issued after ioctl(KVM_CREATE_VM), the VM will
64 not be freed until both the parent (original) process and its child have
65 put their references to the VM's file descriptor.
67 Because a VM's resources are not freed until the last reference to its
68 file descriptor is released, creating additional references to a VM
69 via fork(), dup(), etc... without careful consideration is strongly
70 discouraged and may have unwanted side effects, e.g. memory allocated
71 by and on behalf of the VM's process may not be freed/unaccounted when
78 As of Linux 2.6.22, the KVM ABI has been stabilized: no backward
79 incompatible change are allowed. However, there is an extension
80 facility that allows backward-compatible extensions to the API to be
83 The extension mechanism is not based on the Linux version number.
84 Instead, kvm defines extension identifiers and a facility to query
85 whether a particular extension identifier is available. If it is, a
86 set of ioctls is available for application use.
92 This section describes ioctls that can be used to control kvm guests.
93 For each ioctl, the following information is provided along with a
97 which KVM extension provides this ioctl. Can be 'basic',
98 which means that is will be provided by any kernel that supports
99 API version 12 (see section 4.1), a KVM_CAP_xyz constant, which
100 means availability needs to be checked with KVM_CHECK_EXTENSION
101 (see section 4.4), or 'none' which means that while not all kernels
102 support this ioctl, there's no capability bit to check its
103 availability: for kernels that don't support the ioctl,
104 the ioctl returns -ENOTTY.
107 which instruction set architectures provide this ioctl.
108 x86 includes both i386 and x86_64.
114 what parameters are accepted by the ioctl.
117 the return value. General error numbers (EBADF, ENOMEM, EINVAL)
118 are not detailed, but errors with specific meanings are.
121 4.1 KVM_GET_API_VERSION
122 -----------------------
128 :Returns: the constant KVM_API_VERSION (=12)
130 This identifies the API version as the stable kvm API. It is not
131 expected that this number will change. However, Linux 2.6.20 and
132 2.6.21 report earlier versions; these are not documented and not
133 supported. Applications should refuse to run if KVM_GET_API_VERSION
134 returns a value other than 12. If this check passes, all ioctls
135 described as 'basic' will be available.
144 :Parameters: machine type identifier (KVM_VM_*)
145 :Returns: a VM fd that can be used to control the new virtual machine.
147 The new VM has no virtual cpus and no memory.
148 You probably want to use 0 as machine type.
150 In order to create user controlled virtual machines on S390, check
151 KVM_CAP_S390_UCONTROL and use the flag KVM_VM_S390_UCONTROL as
152 privileged user (CAP_SYS_ADMIN).
154 To use hardware assisted virtualization on MIPS (VZ ASE) rather than
155 the default trap & emulate implementation (which changes the virtual
156 memory layout to fit in user mode), check KVM_CAP_MIPS_VZ and use the
160 On arm64, the physical address size for a VM (IPA Size limit) is limited
161 to 40bits by default. The limit can be configured if the host supports the
162 extension KVM_CAP_ARM_VM_IPA_SIZE. When supported, use
163 KVM_VM_TYPE_ARM_IPA_SIZE(IPA_Bits) to set the size in the machine type
164 identifier, where IPA_Bits is the maximum width of any physical
165 address used by the VM. The IPA_Bits is encoded in bits[7-0] of the
166 machine type identifier.
168 e.g, to configure a guest to use 48bit physical address size::
170 vm_fd = ioctl(dev_fd, KVM_CREATE_VM, KVM_VM_TYPE_ARM_IPA_SIZE(48));
172 The requested size (IPA_Bits) must be:
174 == =========================================================
175 0 Implies default size, 40bits (for backward compatibility)
176 N Implies N bits, where N is a positive integer such that,
177 32 <= N <= Host_IPA_Limit
178 == =========================================================
180 Host_IPA_Limit is the maximum possible value for IPA_Bits on the host and
181 is dependent on the CPU capability and the kernel configuration. The limit can
182 be retrieved using KVM_CAP_ARM_VM_IPA_SIZE of the KVM_CHECK_EXTENSION
185 Creation of the VM will fail if the requested IPA size (whether it is
186 implicit or explicit) is unsupported on the host.
188 Please note that configuring the IPA size does not affect the capability
189 exposed by the guest CPUs in ID_AA64MMFR0_EL1[PARange]. It only affects
190 size of the address translated by the stage2 level (guest physical to
191 host physical address translations).
194 4.3 KVM_GET_MSR_INDEX_LIST, KVM_GET_MSR_FEATURE_INDEX_LIST
195 ----------------------------------------------------------
197 :Capability: basic, KVM_CAP_GET_MSR_FEATURES for KVM_GET_MSR_FEATURE_INDEX_LIST
200 :Parameters: struct kvm_msr_list (in/out)
201 :Returns: 0 on success; -1 on error
205 ====== ============================================================
206 EFAULT the msr index list cannot be read from or written to
207 E2BIG the msr index list is too big to fit in the array specified by
209 ====== ============================================================
213 struct kvm_msr_list {
214 __u32 nmsrs; /* number of msrs in entries */
218 The user fills in the size of the indices array in nmsrs, and in return
219 kvm adjusts nmsrs to reflect the actual number of msrs and fills in the
220 indices array with their numbers.
222 KVM_GET_MSR_INDEX_LIST returns the guest msrs that are supported. The list
223 varies by kvm version and host processor, but does not change otherwise.
225 Note: if kvm indicates supports MCE (KVM_CAP_MCE), then the MCE bank MSRs are
226 not returned in the MSR list, as different vcpus can have a different number
227 of banks, as set via the KVM_X86_SETUP_MCE ioctl.
229 KVM_GET_MSR_FEATURE_INDEX_LIST returns the list of MSRs that can be passed
230 to the KVM_GET_MSRS system ioctl. This lets userspace probe host capabilities
231 and processor features that are exposed via MSRs (e.g., VMX capabilities).
232 This list also varies by kvm version and host processor, but does not change
236 4.4 KVM_CHECK_EXTENSION
237 -----------------------
239 :Capability: basic, KVM_CAP_CHECK_EXTENSION_VM for vm ioctl
241 :Type: system ioctl, vm ioctl
242 :Parameters: extension identifier (KVM_CAP_*)
243 :Returns: 0 if unsupported; 1 (or some other positive integer) if supported
245 The API allows the application to query about extensions to the core
246 kvm API. Userspace passes an extension identifier (an integer) and
247 receives an integer that describes the extension availability.
248 Generally 0 means no and 1 means yes, but some extensions may report
249 additional information in the integer return value.
251 Based on their initialization different VMs may have different capabilities.
252 It is thus encouraged to use the vm ioctl to query for capabilities (available
253 with KVM_CAP_CHECK_EXTENSION_VM on the vm fd)
255 4.5 KVM_GET_VCPU_MMAP_SIZE
256 --------------------------
262 :Returns: size of vcpu mmap area, in bytes
264 The KVM_RUN ioctl (cf.) communicates with userspace via a shared
265 memory region. This ioctl returns the size of that region. See the
266 KVM_RUN documentation for details.
268 Besides the size of the KVM_RUN communication region, other areas of
269 the VCPU file descriptor can be mmap-ed, including:
271 - if KVM_CAP_COALESCED_MMIO is available, a page at
272 KVM_COALESCED_MMIO_PAGE_OFFSET * PAGE_SIZE; for historical reasons,
273 this page is included in the result of KVM_GET_VCPU_MMAP_SIZE.
274 KVM_CAP_COALESCED_MMIO is not documented yet.
276 - if KVM_CAP_DIRTY_LOG_RING is available, a number of pages at
277 KVM_DIRTY_LOG_PAGE_OFFSET * PAGE_SIZE. For more information on
278 KVM_CAP_DIRTY_LOG_RING, see section 8.3.
281 4.6 KVM_SET_MEMORY_REGION
282 -------------------------
287 :Parameters: struct kvm_memory_region (in)
288 :Returns: 0 on success, -1 on error
290 This ioctl is obsolete and has been removed.
299 :Parameters: vcpu id (apic id on x86)
300 :Returns: vcpu fd on success, -1 on error
302 This API adds a vcpu to a virtual machine. No more than max_vcpus may be added.
303 The vcpu id is an integer in the range [0, max_vcpu_id).
305 The recommended max_vcpus value can be retrieved using the KVM_CAP_NR_VCPUS of
306 the KVM_CHECK_EXTENSION ioctl() at run-time.
307 The maximum possible value for max_vcpus can be retrieved using the
308 KVM_CAP_MAX_VCPUS of the KVM_CHECK_EXTENSION ioctl() at run-time.
310 If the KVM_CAP_NR_VCPUS does not exist, you should assume that max_vcpus is 4
312 If the KVM_CAP_MAX_VCPUS does not exist, you should assume that max_vcpus is
313 same as the value returned from KVM_CAP_NR_VCPUS.
315 The maximum possible value for max_vcpu_id can be retrieved using the
316 KVM_CAP_MAX_VCPU_ID of the KVM_CHECK_EXTENSION ioctl() at run-time.
318 If the KVM_CAP_MAX_VCPU_ID does not exist, you should assume that max_vcpu_id
319 is the same as the value returned from KVM_CAP_MAX_VCPUS.
321 On powerpc using book3s_hv mode, the vcpus are mapped onto virtual
322 threads in one or more virtual CPU cores. (This is because the
323 hardware requires all the hardware threads in a CPU core to be in the
324 same partition.) The KVM_CAP_PPC_SMT capability indicates the number
325 of vcpus per virtual core (vcore). The vcore id is obtained by
326 dividing the vcpu id by the number of vcpus per vcore. The vcpus in a
327 given vcore will always be in the same physical core as each other
328 (though that might be a different physical core from time to time).
329 Userspace can control the threading (SMT) mode of the guest by its
330 allocation of vcpu ids. For example, if userspace wants
331 single-threaded guest vcpus, it should make all vcpu ids be a multiple
332 of the number of vcpus per vcore.
334 For virtual cpus that have been created with S390 user controlled virtual
335 machines, the resulting vcpu fd can be memory mapped at page offset
336 KVM_S390_SIE_PAGE_OFFSET in order to obtain a memory map of the virtual
337 cpu's hardware control block.
340 4.8 KVM_GET_DIRTY_LOG (vm ioctl)
341 --------------------------------
346 :Parameters: struct kvm_dirty_log (in/out)
347 :Returns: 0 on success, -1 on error
351 /* for KVM_GET_DIRTY_LOG */
352 struct kvm_dirty_log {
356 void __user *dirty_bitmap; /* one bit per page */
361 Given a memory slot, return a bitmap containing any pages dirtied
362 since the last call to this ioctl. Bit 0 is the first page in the
363 memory slot. Ensure the entire structure is cleared to avoid padding
366 If KVM_CAP_MULTI_ADDRESS_SPACE is available, bits 16-31 of slot field specifies
367 the address space for which you want to return the dirty bitmap. See
368 KVM_SET_USER_MEMORY_REGION for details on the usage of slot field.
370 The bits in the dirty bitmap are cleared before the ioctl returns, unless
371 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is enabled. For more information,
372 see the description of the capability.
374 4.9 KVM_SET_MEMORY_ALIAS
375 ------------------------
380 :Parameters: struct kvm_memory_alias (in)
381 :Returns: 0 (success), -1 (error)
383 This ioctl is obsolete and has been removed.
393 :Returns: 0 on success, -1 on error
397 ======= ==============================================================
398 EINTR an unmasked signal is pending
399 ENOEXEC the vcpu hasn't been initialized or the guest tried to execute
400 instructions from device memory (arm64)
401 ENOSYS data abort outside memslots with no syndrome info and
402 KVM_CAP_ARM_NISV_TO_USER not enabled (arm64)
403 EPERM SVE feature set but not finalized (arm64)
404 ======= ==============================================================
406 This ioctl is used to run a guest virtual cpu. While there are no
407 explicit parameters, there is an implicit parameter block that can be
408 obtained by mmap()ing the vcpu fd at offset 0, with the size given by
409 KVM_GET_VCPU_MMAP_SIZE. The parameter block is formatted as a 'struct
410 kvm_run' (see below).
417 :Architectures: all except ARM, arm64
419 :Parameters: struct kvm_regs (out)
420 :Returns: 0 on success, -1 on error
422 Reads the general purpose registers from the vcpu.
428 /* out (KVM_GET_REGS) / in (KVM_SET_REGS) */
429 __u64 rax, rbx, rcx, rdx;
430 __u64 rsi, rdi, rsp, rbp;
431 __u64 r8, r9, r10, r11;
432 __u64 r12, r13, r14, r15;
438 /* out (KVM_GET_REGS) / in (KVM_SET_REGS) */
450 :Architectures: all except ARM, arm64
452 :Parameters: struct kvm_regs (in)
453 :Returns: 0 on success, -1 on error
455 Writes the general purpose registers into the vcpu.
457 See KVM_GET_REGS for the data structure.
464 :Architectures: x86, ppc
466 :Parameters: struct kvm_sregs (out)
467 :Returns: 0 on success, -1 on error
469 Reads special registers from the vcpu.
475 struct kvm_segment cs, ds, es, fs, gs, ss;
476 struct kvm_segment tr, ldt;
477 struct kvm_dtable gdt, idt;
478 __u64 cr0, cr2, cr3, cr4, cr8;
481 __u64 interrupt_bitmap[(KVM_NR_INTERRUPTS + 63) / 64];
484 /* ppc -- see arch/powerpc/include/uapi/asm/kvm.h */
486 interrupt_bitmap is a bitmap of pending external interrupts. At most
487 one bit may be set. This interrupt has been acknowledged by the APIC
488 but not yet injected into the cpu core.
495 :Architectures: x86, ppc
497 :Parameters: struct kvm_sregs (in)
498 :Returns: 0 on success, -1 on error
500 Writes special registers into the vcpu. See KVM_GET_SREGS for the
510 :Parameters: struct kvm_translation (in/out)
511 :Returns: 0 on success, -1 on error
513 Translates a virtual address according to the vcpu's current address
518 struct kvm_translation {
520 __u64 linear_address;
523 __u64 physical_address;
535 :Architectures: x86, ppc, mips
537 :Parameters: struct kvm_interrupt (in)
538 :Returns: 0 on success, negative on failure.
540 Queues a hardware interrupt vector to be injected.
544 /* for KVM_INTERRUPT */
545 struct kvm_interrupt {
555 ========= ===================================
557 -EEXIST if an interrupt is already enqueued
558 -EINVAL the irq number is invalid
559 -ENXIO if the PIC is in the kernel
560 -EFAULT if the pointer is invalid
561 ========= ===================================
563 Note 'irq' is an interrupt vector, not an interrupt pin or line. This
564 ioctl is useful if the in-kernel PIC is not used.
569 Queues an external interrupt to be injected. This ioctl is overleaded
570 with 3 different irq values:
574 This injects an edge type external interrupt into the guest once it's ready
575 to receive interrupts. When injected, the interrupt is done.
577 b) KVM_INTERRUPT_UNSET
579 This unsets any pending interrupt.
581 Only available with KVM_CAP_PPC_UNSET_IRQ.
583 c) KVM_INTERRUPT_SET_LEVEL
585 This injects a level type external interrupt into the guest context. The
586 interrupt stays pending until a specific ioctl with KVM_INTERRUPT_UNSET
589 Only available with KVM_CAP_PPC_IRQ_LEVEL.
591 Note that any value for 'irq' other than the ones stated above is invalid
592 and incurs unexpected behavior.
594 This is an asynchronous vcpu ioctl and can be invoked from any thread.
599 Queues an external interrupt to be injected into the virtual CPU. A negative
600 interrupt number dequeues the interrupt.
602 This is an asynchronous vcpu ioctl and can be invoked from any thread.
612 :Returns: -1 on error
614 Support for this has been removed. Use KVM_SET_GUEST_DEBUG instead.
620 :Capability: basic (vcpu), KVM_CAP_GET_MSR_FEATURES (system)
622 :Type: system ioctl, vcpu ioctl
623 :Parameters: struct kvm_msrs (in/out)
624 :Returns: number of msrs successfully returned;
627 When used as a system ioctl:
628 Reads the values of MSR-based features that are available for the VM. This
629 is similar to KVM_GET_SUPPORTED_CPUID, but it returns MSR indices and values.
630 The list of msr-based features can be obtained using KVM_GET_MSR_FEATURE_INDEX_LIST
633 When used as a vcpu ioctl:
634 Reads model-specific registers from the vcpu. Supported msr indices can
635 be obtained using KVM_GET_MSR_INDEX_LIST in a system ioctl.
640 __u32 nmsrs; /* number of msrs in entries */
643 struct kvm_msr_entry entries[0];
646 struct kvm_msr_entry {
652 Application code should set the 'nmsrs' member (which indicates the
653 size of the entries array) and the 'index' member of each array entry.
654 kvm will fill in the 'data' member.
663 :Parameters: struct kvm_msrs (in)
664 :Returns: number of msrs successfully set (see below), -1 on error
666 Writes model-specific registers to the vcpu. See KVM_GET_MSRS for the
669 Application code should set the 'nmsrs' member (which indicates the
670 size of the entries array), and the 'index' and 'data' members of each
673 It tries to set the MSRs in array entries[] one by one. If setting an MSR
674 fails, e.g., due to setting reserved bits, the MSR isn't supported/emulated
675 by KVM, etc..., it stops processing the MSR list and returns the number of
676 MSRs that have been set successfully.
685 :Parameters: struct kvm_cpuid (in)
686 :Returns: 0 on success, -1 on error
688 Defines the vcpu responses to the cpuid instruction. Applications
689 should use the KVM_SET_CPUID2 ioctl if available.
691 Note, when this IOCTL fails, KVM gives no guarantees that previous valid CPUID
692 configuration (if there is) is not corrupted. Userspace can get a copy of the
693 resulting CPUID configuration through KVM_GET_CPUID2 in case.
697 struct kvm_cpuid_entry {
706 /* for KVM_SET_CPUID */
710 struct kvm_cpuid_entry entries[0];
714 4.21 KVM_SET_SIGNAL_MASK
715 ------------------------
720 :Parameters: struct kvm_signal_mask (in)
721 :Returns: 0 on success, -1 on error
723 Defines which signals are blocked during execution of KVM_RUN. This
724 signal mask temporarily overrides the threads signal mask. Any
725 unblocked signal received (except SIGKILL and SIGSTOP, which retain
726 their traditional behaviour) will cause KVM_RUN to return with -EINTR.
728 Note the signal will only be delivered if not blocked by the original
733 /* for KVM_SET_SIGNAL_MASK */
734 struct kvm_signal_mask {
746 :Parameters: struct kvm_fpu (out)
747 :Returns: 0 on success, -1 on error
749 Reads the floating point state from the vcpu.
753 /* for KVM_GET_FPU and KVM_SET_FPU */
758 __u8 ftwx; /* in fxsave format */
775 :Parameters: struct kvm_fpu (in)
776 :Returns: 0 on success, -1 on error
778 Writes the floating point state to the vcpu.
782 /* for KVM_GET_FPU and KVM_SET_FPU */
787 __u8 ftwx; /* in fxsave format */
798 4.24 KVM_CREATE_IRQCHIP
799 -----------------------
801 :Capability: KVM_CAP_IRQCHIP, KVM_CAP_S390_IRQCHIP (s390)
802 :Architectures: x86, ARM, arm64, s390
805 :Returns: 0 on success, -1 on error
807 Creates an interrupt controller model in the kernel.
808 On x86, creates a virtual ioapic, a virtual PIC (two PICs, nested), and sets up
809 future vcpus to have a local APIC. IRQ routing for GSIs 0-15 is set to both
810 PIC and IOAPIC; GSI 16-23 only go to the IOAPIC.
811 On ARM/arm64, a GICv2 is created. Any other GIC versions require the usage of
812 KVM_CREATE_DEVICE, which also supports creating a GICv2. Using
813 KVM_CREATE_DEVICE is preferred over KVM_CREATE_IRQCHIP for GICv2.
814 On s390, a dummy irq routing table is created.
816 Note that on s390 the KVM_CAP_S390_IRQCHIP vm capability needs to be enabled
817 before KVM_CREATE_IRQCHIP can be used.
823 :Capability: KVM_CAP_IRQCHIP
824 :Architectures: x86, arm, arm64
826 :Parameters: struct kvm_irq_level
827 :Returns: 0 on success, -1 on error
829 Sets the level of a GSI input to the interrupt controller model in the kernel.
830 On some architectures it is required that an interrupt controller model has
831 been previously created with KVM_CREATE_IRQCHIP. Note that edge-triggered
832 interrupts require the level to be set to 1 and then back to 0.
834 On real hardware, interrupt pins can be active-low or active-high. This
835 does not matter for the level field of struct kvm_irq_level: 1 always
836 means active (asserted), 0 means inactive (deasserted).
838 x86 allows the operating system to program the interrupt polarity
839 (active-low/active-high) for level-triggered interrupts, and KVM used
840 to consider the polarity. However, due to bitrot in the handling of
841 active-low interrupts, the above convention is now valid on x86 too.
842 This is signaled by KVM_CAP_X86_IOAPIC_POLARITY_IGNORED. Userspace
843 should not present interrupts to the guest as active-low unless this
844 capability is present (or unless it is not using the in-kernel irqchip,
848 ARM/arm64 can signal an interrupt either at the CPU level, or at the
849 in-kernel irqchip (GIC), and for in-kernel irqchip can tell the GIC to
850 use PPIs designated for specific cpus. The irq field is interpreted
853 Â bits: | 31 ... 28 | 27 ... 24 | 23 ... 16 | 15 ... 0 |
854 field: | vcpu2_index | irq_type | vcpu_index | irq_id |
856 The irq_type field has the following values:
859 out-of-kernel GIC: irq_id 0 is IRQ, irq_id 1 is FIQ
861 in-kernel GIC: SPI, irq_id between 32 and 1019 (incl.)
862 (the vcpu_index field is ignored)
864 in-kernel GIC: PPI, irq_id between 16 and 31 (incl.)
866 (The irq_id field thus corresponds nicely to the IRQ ID in the ARM GIC specs)
868 In both cases, level is used to assert/deassert the line.
870 When KVM_CAP_ARM_IRQ_LINE_LAYOUT_2 is supported, the target vcpu is
871 identified as (256 * vcpu2_index + vcpu_index). Otherwise, vcpu2_index
874 Note that on arm/arm64, the KVM_CAP_IRQCHIP capability only conditions
875 injection of interrupts for the in-kernel irqchip. KVM_IRQ_LINE can always
876 be used for a userspace interrupt controller.
880 struct kvm_irq_level {
883 __s32 status; /* not used for KVM_IRQ_LEVEL */
885 __u32 level; /* 0 or 1 */
892 :Capability: KVM_CAP_IRQCHIP
895 :Parameters: struct kvm_irqchip (in/out)
896 :Returns: 0 on success, -1 on error
898 Reads the state of a kernel interrupt controller created with
899 KVM_CREATE_IRQCHIP into a buffer provided by the caller.
904 __u32 chip_id; /* 0 = PIC1, 1 = PIC2, 2 = IOAPIC */
907 char dummy[512]; /* reserving space */
908 struct kvm_pic_state pic;
909 struct kvm_ioapic_state ioapic;
917 :Capability: KVM_CAP_IRQCHIP
920 :Parameters: struct kvm_irqchip (in)
921 :Returns: 0 on success, -1 on error
923 Sets the state of a kernel interrupt controller created with
924 KVM_CREATE_IRQCHIP from a buffer provided by the caller.
929 __u32 chip_id; /* 0 = PIC1, 1 = PIC2, 2 = IOAPIC */
932 char dummy[512]; /* reserving space */
933 struct kvm_pic_state pic;
934 struct kvm_ioapic_state ioapic;
939 4.28 KVM_XEN_HVM_CONFIG
940 -----------------------
942 :Capability: KVM_CAP_XEN_HVM
945 :Parameters: struct kvm_xen_hvm_config (in)
946 :Returns: 0 on success, -1 on error
948 Sets the MSR that the Xen HVM guest uses to initialize its hypercall
949 page, and provides the starting address and size of the hypercall
950 blobs in userspace. When the guest writes the MSR, kvm copies one
951 page of a blob (32- or 64-bit, depending on the vcpu mode) to guest
956 struct kvm_xen_hvm_config {
966 If the KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL flag is returned from the
967 KVM_CAP_XEN_HVM check, it may be set in the flags field of this ioctl.
968 This requests KVM to generate the contents of the hypercall page
969 automatically; hypercalls will be intercepted and passed to userspace
970 through KVM_EXIT_XEN. In this case, all of the blob size and address
973 No other flags are currently valid in the struct kvm_xen_hvm_config.
978 :Capability: KVM_CAP_ADJUST_CLOCK
981 :Parameters: struct kvm_clock_data (out)
982 :Returns: 0 on success, -1 on error
984 Gets the current timestamp of kvmclock as seen by the current guest. In
985 conjunction with KVM_SET_CLOCK, it is used to ensure monotonicity on scenarios
988 When KVM_CAP_ADJUST_CLOCK is passed to KVM_CHECK_EXTENSION, it returns the
989 set of bits that KVM can return in struct kvm_clock_data's flag member.
991 The only flag defined now is KVM_CLOCK_TSC_STABLE. If set, the returned
992 value is the exact kvmclock value seen by all VCPUs at the instant
993 when KVM_GET_CLOCK was called. If clear, the returned value is simply
994 CLOCK_MONOTONIC plus a constant offset; the offset can be modified
995 with KVM_SET_CLOCK. KVM will try to make all VCPUs follow this clock,
996 but the exact value read by each VCPU could differ, because the host
1001 struct kvm_clock_data {
1002 __u64 clock; /* kvmclock current value */
1011 :Capability: KVM_CAP_ADJUST_CLOCK
1014 :Parameters: struct kvm_clock_data (in)
1015 :Returns: 0 on success, -1 on error
1017 Sets the current timestamp of kvmclock to the value specified in its parameter.
1018 In conjunction with KVM_GET_CLOCK, it is used to ensure monotonicity on scenarios
1023 struct kvm_clock_data {
1024 __u64 clock; /* kvmclock current value */
1030 4.31 KVM_GET_VCPU_EVENTS
1031 ------------------------
1033 :Capability: KVM_CAP_VCPU_EVENTS
1034 :Extended by: KVM_CAP_INTR_SHADOW
1035 :Architectures: x86, arm, arm64
1037 :Parameters: struct kvm_vcpu_event (out)
1038 :Returns: 0 on success, -1 on error
1043 Gets currently pending exceptions, interrupts, and NMIs as well as related
1048 struct kvm_vcpu_events {
1052 __u8 has_error_code;
1073 __u8 smm_inside_nmi;
1077 __u8 exception_has_payload;
1078 __u64 exception_payload;
1081 The following bits are defined in the flags field:
1083 - KVM_VCPUEVENT_VALID_SHADOW may be set to signal that
1084 interrupt.shadow contains a valid state.
1086 - KVM_VCPUEVENT_VALID_SMM may be set to signal that smi contains a
1089 - KVM_VCPUEVENT_VALID_PAYLOAD may be set to signal that the
1090 exception_has_payload, exception_payload, and exception.pending
1091 fields contain a valid state. This bit will be set whenever
1092 KVM_CAP_EXCEPTION_PAYLOAD is enabled.
1097 If the guest accesses a device that is being emulated by the host kernel in
1098 such a way that a real device would generate a physical SError, KVM may make
1099 a virtual SError pending for that VCPU. This system error interrupt remains
1100 pending until the guest takes the exception by unmasking PSTATE.A.
1102 Running the VCPU may cause it to take a pending SError, or make an access that
1103 causes an SError to become pending. The event's description is only valid while
1104 the VPCU is not running.
1106 This API provides a way to read and write the pending 'event' state that is not
1107 visible to the guest. To save, restore or migrate a VCPU the struct representing
1108 the state can be read then written using this GET/SET API, along with the other
1109 guest-visible registers. It is not possible to 'cancel' an SError that has been
1112 A device being emulated in user-space may also wish to generate an SError. To do
1113 this the events structure can be populated by user-space. The current state
1114 should be read first, to ensure no existing SError is pending. If an existing
1115 SError is pending, the architecture's 'Multiple SError interrupts' rules should
1116 be followed. (2.5.3 of DDI0587.a "ARM Reliability, Availability, and
1117 Serviceability (RAS) Specification").
1119 SError exceptions always have an ESR value. Some CPUs have the ability to
1120 specify what the virtual SError's ESR value should be. These systems will
1121 advertise KVM_CAP_ARM_INJECT_SERROR_ESR. In this case exception.has_esr will
1122 always have a non-zero value when read, and the agent making an SError pending
1123 should specify the ISS field in the lower 24 bits of exception.serror_esr. If
1124 the system supports KVM_CAP_ARM_INJECT_SERROR_ESR, but user-space sets the events
1125 with exception.has_esr as zero, KVM will choose an ESR.
1127 Specifying exception.has_esr on a system that does not support it will return
1128 -EINVAL. Setting anything other than the lower 24bits of exception.serror_esr
1129 will return -EINVAL.
1131 It is not possible to read back a pending external abort (injected via
1132 KVM_SET_VCPU_EVENTS or otherwise) because such an exception is always delivered
1133 directly to the virtual CPU).
1137 struct kvm_vcpu_events {
1139 __u8 serror_pending;
1140 __u8 serror_has_esr;
1141 __u8 ext_dabt_pending;
1142 /* Align it to 8 bytes */
1149 4.32 KVM_SET_VCPU_EVENTS
1150 ------------------------
1152 :Capability: KVM_CAP_VCPU_EVENTS
1153 :Extended by: KVM_CAP_INTR_SHADOW
1154 :Architectures: x86, arm, arm64
1156 :Parameters: struct kvm_vcpu_event (in)
1157 :Returns: 0 on success, -1 on error
1162 Set pending exceptions, interrupts, and NMIs as well as related states of the
1165 See KVM_GET_VCPU_EVENTS for the data structure.
1167 Fields that may be modified asynchronously by running VCPUs can be excluded
1168 from the update. These fields are nmi.pending, sipi_vector, smi.smm,
1169 smi.pending. Keep the corresponding bits in the flags field cleared to
1170 suppress overwriting the current in-kernel state. The bits are:
1172 =============================== ==================================
1173 KVM_VCPUEVENT_VALID_NMI_PENDING transfer nmi.pending to the kernel
1174 KVM_VCPUEVENT_VALID_SIPI_VECTOR transfer sipi_vector
1175 KVM_VCPUEVENT_VALID_SMM transfer the smi sub-struct.
1176 =============================== ==================================
1178 If KVM_CAP_INTR_SHADOW is available, KVM_VCPUEVENT_VALID_SHADOW can be set in
1179 the flags field to signal that interrupt.shadow contains a valid state and
1180 shall be written into the VCPU.
1182 KVM_VCPUEVENT_VALID_SMM can only be set if KVM_CAP_X86_SMM is available.
1184 If KVM_CAP_EXCEPTION_PAYLOAD is enabled, KVM_VCPUEVENT_VALID_PAYLOAD
1185 can be set in the flags field to signal that the
1186 exception_has_payload, exception_payload, and exception.pending fields
1187 contain a valid state and shall be written into the VCPU.
1192 User space may need to inject several types of events to the guest.
1194 Set the pending SError exception state for this VCPU. It is not possible to
1195 'cancel' an Serror that has been made pending.
1197 If the guest performed an access to I/O memory which could not be handled by
1198 userspace, for example because of missing instruction syndrome decode
1199 information or because there is no device mapped at the accessed IPA, then
1200 userspace can ask the kernel to inject an external abort using the address
1201 from the exiting fault on the VCPU. It is a programming error to set
1202 ext_dabt_pending after an exit which was not either KVM_EXIT_MMIO or
1203 KVM_EXIT_ARM_NISV. This feature is only available if the system supports
1204 KVM_CAP_ARM_INJECT_EXT_DABT. This is a helper which provides commonality in
1205 how userspace reports accesses for the above cases to guests, across different
1206 userspace implementations. Nevertheless, userspace can still emulate all Arm
1207 exceptions by manipulating individual registers using the KVM_SET_ONE_REG API.
1209 See KVM_GET_VCPU_EVENTS for the data structure.
1212 4.33 KVM_GET_DEBUGREGS
1213 ----------------------
1215 :Capability: KVM_CAP_DEBUGREGS
1218 :Parameters: struct kvm_debugregs (out)
1219 :Returns: 0 on success, -1 on error
1221 Reads debug registers from the vcpu.
1225 struct kvm_debugregs {
1234 4.34 KVM_SET_DEBUGREGS
1235 ----------------------
1237 :Capability: KVM_CAP_DEBUGREGS
1240 :Parameters: struct kvm_debugregs (in)
1241 :Returns: 0 on success, -1 on error
1243 Writes debug registers into the vcpu.
1245 See KVM_GET_DEBUGREGS for the data structure. The flags field is unused
1246 yet and must be cleared on entry.
1249 4.35 KVM_SET_USER_MEMORY_REGION
1250 -------------------------------
1252 :Capability: KVM_CAP_USER_MEMORY
1255 :Parameters: struct kvm_userspace_memory_region (in)
1256 :Returns: 0 on success, -1 on error
1260 struct kvm_userspace_memory_region {
1263 __u64 guest_phys_addr;
1264 __u64 memory_size; /* bytes */
1265 __u64 userspace_addr; /* start of the userspace allocated memory */
1268 /* for kvm_memory_region::flags */
1269 #define KVM_MEM_LOG_DIRTY_PAGES (1UL << 0)
1270 #define KVM_MEM_READONLY (1UL << 1)
1272 This ioctl allows the user to create, modify or delete a guest physical
1273 memory slot. Bits 0-15 of "slot" specify the slot id and this value
1274 should be less than the maximum number of user memory slots supported per
1275 VM. The maximum allowed slots can be queried using KVM_CAP_NR_MEMSLOTS.
1276 Slots may not overlap in guest physical address space.
1278 If KVM_CAP_MULTI_ADDRESS_SPACE is available, bits 16-31 of "slot"
1279 specifies the address space which is being modified. They must be
1280 less than the value that KVM_CHECK_EXTENSION returns for the
1281 KVM_CAP_MULTI_ADDRESS_SPACE capability. Slots in separate address spaces
1282 are unrelated; the restriction on overlapping slots only applies within
1285 Deleting a slot is done by passing zero for memory_size. When changing
1286 an existing slot, it may be moved in the guest physical memory space,
1287 or its flags may be modified, but it may not be resized.
1289 Memory for the region is taken starting at the address denoted by the
1290 field userspace_addr, which must point at user addressable memory for
1291 the entire memory slot size. Any object may back this memory, including
1292 anonymous memory, ordinary files, and hugetlbfs.
1294 On architectures that support a form of address tagging, userspace_addr must
1295 be an untagged address.
1297 It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr
1298 be identical. This allows large pages in the guest to be backed by large
1301 The flags field supports two flags: KVM_MEM_LOG_DIRTY_PAGES and
1302 KVM_MEM_READONLY. The former can be set to instruct KVM to keep track of
1303 writes to memory within the slot. See KVM_GET_DIRTY_LOG ioctl to know how to
1304 use it. The latter can be set, if KVM_CAP_READONLY_MEM capability allows it,
1305 to make a new slot read-only. In this case, writes to this memory will be
1306 posted to userspace as KVM_EXIT_MMIO exits.
1308 When the KVM_CAP_SYNC_MMU capability is available, changes in the backing of
1309 the memory region are automatically reflected into the guest. For example, an
1310 mmap() that affects the region will be made visible immediately. Another
1311 example is madvise(MADV_DROP).
1313 It is recommended to use this API instead of the KVM_SET_MEMORY_REGION ioctl.
1314 The KVM_SET_MEMORY_REGION does not allow fine grained control over memory
1315 allocation and is deprecated.
1318 4.36 KVM_SET_TSS_ADDR
1319 ---------------------
1321 :Capability: KVM_CAP_SET_TSS_ADDR
1324 :Parameters: unsigned long tss_address (in)
1325 :Returns: 0 on success, -1 on error
1327 This ioctl defines the physical address of a three-page region in the guest
1328 physical address space. The region must be within the first 4GB of the
1329 guest physical address space and must not conflict with any memory slot
1330 or any mmio address. The guest may malfunction if it accesses this memory
1333 This ioctl is required on Intel-based hosts. This is needed on Intel hardware
1334 because of a quirk in the virtualization implementation (see the internals
1335 documentation when it pops into existence).
1341 :Capability: KVM_CAP_ENABLE_CAP
1342 :Architectures: mips, ppc, s390
1344 :Parameters: struct kvm_enable_cap (in)
1345 :Returns: 0 on success; -1 on error
1347 :Capability: KVM_CAP_ENABLE_CAP_VM
1350 :Parameters: struct kvm_enable_cap (in)
1351 :Returns: 0 on success; -1 on error
1355 Not all extensions are enabled by default. Using this ioctl the application
1356 can enable an extension, making it available to the guest.
1358 On systems that do not support this ioctl, it always fails. On systems that
1359 do support it, it only works for extensions that are supported for enablement.
1361 To check if a capability can be enabled, the KVM_CHECK_EXTENSION ioctl should
1366 struct kvm_enable_cap {
1370 The capability that is supposed to get enabled.
1376 A bitfield indicating future enhancements. Has to be 0 for now.
1382 Arguments for enabling a feature. If a feature needs initial values to
1383 function properly, this is the place to put them.
1390 The vcpu ioctl should be used for vcpu-specific capabilities, the vm ioctl
1391 for vm-wide capabilities.
1393 4.38 KVM_GET_MP_STATE
1394 ---------------------
1396 :Capability: KVM_CAP_MP_STATE
1397 :Architectures: x86, s390, arm, arm64
1399 :Parameters: struct kvm_mp_state (out)
1400 :Returns: 0 on success; -1 on error
1404 struct kvm_mp_state {
1408 Returns the vcpu's current "multiprocessing state" (though also valid on
1409 uniprocessor guests).
1411 Possible values are:
1413 ========================== ===============================================
1414 KVM_MP_STATE_RUNNABLE the vcpu is currently running [x86,arm/arm64]
1415 KVM_MP_STATE_UNINITIALIZED the vcpu is an application processor (AP)
1416 which has not yet received an INIT signal [x86]
1417 KVM_MP_STATE_INIT_RECEIVED the vcpu has received an INIT signal, and is
1418 now ready for a SIPI [x86]
1419 KVM_MP_STATE_HALTED the vcpu has executed a HLT instruction and
1420 is waiting for an interrupt [x86]
1421 KVM_MP_STATE_SIPI_RECEIVED the vcpu has just received a SIPI (vector
1422 accessible via KVM_GET_VCPU_EVENTS) [x86]
1423 KVM_MP_STATE_STOPPED the vcpu is stopped [s390,arm/arm64]
1424 KVM_MP_STATE_CHECK_STOP the vcpu is in a special error state [s390]
1425 KVM_MP_STATE_OPERATING the vcpu is operating (running or halted)
1427 KVM_MP_STATE_LOAD the vcpu is in a special load/startup state
1429 ========================== ===============================================
1431 On x86, this ioctl is only useful after KVM_CREATE_IRQCHIP. Without an
1432 in-kernel irqchip, the multiprocessing state must be maintained by userspace on
1433 these architectures.
1438 The only states that are valid are KVM_MP_STATE_STOPPED and
1439 KVM_MP_STATE_RUNNABLE which reflect if the vcpu is paused or not.
1441 4.39 KVM_SET_MP_STATE
1442 ---------------------
1444 :Capability: KVM_CAP_MP_STATE
1445 :Architectures: x86, s390, arm, arm64
1447 :Parameters: struct kvm_mp_state (in)
1448 :Returns: 0 on success; -1 on error
1450 Sets the vcpu's current "multiprocessing state"; see KVM_GET_MP_STATE for
1453 On x86, this ioctl is only useful after KVM_CREATE_IRQCHIP. Without an
1454 in-kernel irqchip, the multiprocessing state must be maintained by userspace on
1455 these architectures.
1460 The only states that are valid are KVM_MP_STATE_STOPPED and
1461 KVM_MP_STATE_RUNNABLE which reflect if the vcpu should be paused or not.
1463 4.40 KVM_SET_IDENTITY_MAP_ADDR
1464 ------------------------------
1466 :Capability: KVM_CAP_SET_IDENTITY_MAP_ADDR
1469 :Parameters: unsigned long identity (in)
1470 :Returns: 0 on success, -1 on error
1472 This ioctl defines the physical address of a one-page region in the guest
1473 physical address space. The region must be within the first 4GB of the
1474 guest physical address space and must not conflict with any memory slot
1475 or any mmio address. The guest may malfunction if it accesses this memory
1478 Setting the address to 0 will result in resetting the address to its default
1481 This ioctl is required on Intel-based hosts. This is needed on Intel hardware
1482 because of a quirk in the virtualization implementation (see the internals
1483 documentation when it pops into existence).
1485 Fails if any VCPU has already been created.
1487 4.41 KVM_SET_BOOT_CPU_ID
1488 ------------------------
1490 :Capability: KVM_CAP_SET_BOOT_CPU_ID
1493 :Parameters: unsigned long vcpu_id
1494 :Returns: 0 on success, -1 on error
1496 Define which vcpu is the Bootstrap Processor (BSP). Values are the same
1497 as the vcpu id in KVM_CREATE_VCPU. If this ioctl is not called, the default
1498 is vcpu 0. This ioctl has to be called before vcpu creation,
1499 otherwise it will return EBUSY error.
1505 :Capability: KVM_CAP_XSAVE
1508 :Parameters: struct kvm_xsave (out)
1509 :Returns: 0 on success, -1 on error
1518 This ioctl would copy current vcpu's xsave struct to the userspace.
1524 :Capability: KVM_CAP_XSAVE
1527 :Parameters: struct kvm_xsave (in)
1528 :Returns: 0 on success, -1 on error
1537 This ioctl would copy userspace's xsave struct to the kernel.
1543 :Capability: KVM_CAP_XCRS
1546 :Parameters: struct kvm_xcrs (out)
1547 :Returns: 0 on success, -1 on error
1560 struct kvm_xcr xcrs[KVM_MAX_XCRS];
1564 This ioctl would copy current vcpu's xcrs to the userspace.
1570 :Capability: KVM_CAP_XCRS
1573 :Parameters: struct kvm_xcrs (in)
1574 :Returns: 0 on success, -1 on error
1587 struct kvm_xcr xcrs[KVM_MAX_XCRS];
1591 This ioctl would set vcpu's xcr to the value userspace specified.
1594 4.46 KVM_GET_SUPPORTED_CPUID
1595 ----------------------------
1597 :Capability: KVM_CAP_EXT_CPUID
1600 :Parameters: struct kvm_cpuid2 (in/out)
1601 :Returns: 0 on success, -1 on error
1608 struct kvm_cpuid_entry2 entries[0];
1611 #define KVM_CPUID_FLAG_SIGNIFCANT_INDEX BIT(0)
1612 #define KVM_CPUID_FLAG_STATEFUL_FUNC BIT(1) /* deprecated */
1613 #define KVM_CPUID_FLAG_STATE_READ_NEXT BIT(2) /* deprecated */
1615 struct kvm_cpuid_entry2 {
1626 This ioctl returns x86 cpuid features which are supported by both the
1627 hardware and kvm in its default configuration. Userspace can use the
1628 information returned by this ioctl to construct cpuid information (for
1629 KVM_SET_CPUID2) that is consistent with hardware, kernel, and
1630 userspace capabilities, and with user requirements (for example, the
1631 user may wish to constrain cpuid to emulate older hardware, or for
1632 feature consistency across a cluster).
1634 Note that certain capabilities, such as KVM_CAP_X86_DISABLE_EXITS, may
1635 expose cpuid features (e.g. MONITOR) which are not supported by kvm in
1636 its default configuration. If userspace enables such capabilities, it
1637 is responsible for modifying the results of this ioctl appropriately.
1639 Userspace invokes KVM_GET_SUPPORTED_CPUID by passing a kvm_cpuid2 structure
1640 with the 'nent' field indicating the number of entries in the variable-size
1641 array 'entries'. If the number of entries is too low to describe the cpu
1642 capabilities, an error (E2BIG) is returned. If the number is too high,
1643 the 'nent' field is adjusted and an error (ENOMEM) is returned. If the
1644 number is just right, the 'nent' field is adjusted to the number of valid
1645 entries in the 'entries' array, which is then filled.
1647 The entries returned are the host cpuid as returned by the cpuid instruction,
1648 with unknown or unsupported features masked out. Some features (for example,
1649 x2apic), may not be present in the host cpu, but are exposed by kvm if it can
1650 emulate them efficiently. The fields in each entry are defined as follows:
1653 the eax value used to obtain the entry
1656 the ecx value used to obtain the entry (for entries that are
1660 an OR of zero or more of the following:
1662 KVM_CPUID_FLAG_SIGNIFCANT_INDEX:
1663 if the index field is valid
1666 the values returned by the cpuid instruction for
1667 this function/index combination
1669 The TSC deadline timer feature (CPUID leaf 1, ecx[24]) is always returned
1670 as false, since the feature depends on KVM_CREATE_IRQCHIP for local APIC
1671 support. Instead it is reported via::
1673 ioctl(KVM_CHECK_EXTENSION, KVM_CAP_TSC_DEADLINE_TIMER)
1675 if that returns true and you use KVM_CREATE_IRQCHIP, or if you emulate the
1676 feature in userspace, then you can enable the feature for KVM_SET_CPUID2.
1679 4.47 KVM_PPC_GET_PVINFO
1680 -----------------------
1682 :Capability: KVM_CAP_PPC_GET_PVINFO
1685 :Parameters: struct kvm_ppc_pvinfo (out)
1686 :Returns: 0 on success, !0 on error
1690 struct kvm_ppc_pvinfo {
1696 This ioctl fetches PV specific information that need to be passed to the guest
1697 using the device tree or other means from vm context.
1699 The hcall array defines 4 instructions that make up a hypercall.
1701 If any additional field gets added to this structure later on, a bit for that
1702 additional piece of information will be set in the flags bitmap.
1704 The flags bitmap is defined as::
1706 /* the host supports the ePAPR idle hcall
1707 #define KVM_PPC_PVINFO_FLAGS_EV_IDLE (1<<0)
1709 4.52 KVM_SET_GSI_ROUTING
1710 ------------------------
1712 :Capability: KVM_CAP_IRQ_ROUTING
1713 :Architectures: x86 s390 arm arm64
1715 :Parameters: struct kvm_irq_routing (in)
1716 :Returns: 0 on success, -1 on error
1718 Sets the GSI routing table entries, overwriting any previously set entries.
1720 On arm/arm64, GSI routing has the following limitation:
1722 - GSI routing does not apply to KVM_IRQ_LINE but only to KVM_IRQFD.
1726 struct kvm_irq_routing {
1729 struct kvm_irq_routing_entry entries[0];
1732 No flags are specified so far, the corresponding field must be set to zero.
1736 struct kvm_irq_routing_entry {
1742 struct kvm_irq_routing_irqchip irqchip;
1743 struct kvm_irq_routing_msi msi;
1744 struct kvm_irq_routing_s390_adapter adapter;
1745 struct kvm_irq_routing_hv_sint hv_sint;
1750 /* gsi routing entry types */
1751 #define KVM_IRQ_ROUTING_IRQCHIP 1
1752 #define KVM_IRQ_ROUTING_MSI 2
1753 #define KVM_IRQ_ROUTING_S390_ADAPTER 3
1754 #define KVM_IRQ_ROUTING_HV_SINT 4
1758 - KVM_MSI_VALID_DEVID: used along with KVM_IRQ_ROUTING_MSI routing entry
1759 type, specifies that the devid field contains a valid value. The per-VM
1760 KVM_CAP_MSI_DEVID capability advertises the requirement to provide
1761 the device ID. If this capability is not available, userspace should
1762 never set the KVM_MSI_VALID_DEVID flag as the ioctl might fail.
1767 struct kvm_irq_routing_irqchip {
1772 struct kvm_irq_routing_msi {
1782 If KVM_MSI_VALID_DEVID is set, devid contains a unique device identifier
1783 for the device that wrote the MSI message. For PCI, this is usually a
1784 BFD identifier in the lower 16 bits.
1786 On x86, address_hi is ignored unless the KVM_X2APIC_API_USE_32BIT_IDS
1787 feature of KVM_CAP_X2APIC_API capability is enabled. If it is enabled,
1788 address_hi bits 31-8 provide bits 31-8 of the destination id. Bits 7-0 of
1789 address_hi must be zero.
1793 struct kvm_irq_routing_s390_adapter {
1797 __u32 summary_offset;
1801 struct kvm_irq_routing_hv_sint {
1807 4.55 KVM_SET_TSC_KHZ
1808 --------------------
1810 :Capability: KVM_CAP_TSC_CONTROL
1813 :Parameters: virtual tsc_khz
1814 :Returns: 0 on success, -1 on error
1816 Specifies the tsc frequency for the virtual machine. The unit of the
1820 4.56 KVM_GET_TSC_KHZ
1821 --------------------
1823 :Capability: KVM_CAP_GET_TSC_KHZ
1827 :Returns: virtual tsc-khz on success, negative value on error
1829 Returns the tsc frequency of the guest. The unit of the return value is
1830 KHz. If the host has unstable tsc this ioctl returns -EIO instead as an
1837 :Capability: KVM_CAP_IRQCHIP
1840 :Parameters: struct kvm_lapic_state (out)
1841 :Returns: 0 on success, -1 on error
1845 #define KVM_APIC_REG_SIZE 0x400
1846 struct kvm_lapic_state {
1847 char regs[KVM_APIC_REG_SIZE];
1850 Reads the Local APIC registers and copies them into the input argument. The
1851 data format and layout are the same as documented in the architecture manual.
1853 If KVM_X2APIC_API_USE_32BIT_IDS feature of KVM_CAP_X2APIC_API is
1854 enabled, then the format of APIC_ID register depends on the APIC mode
1855 (reported by MSR_IA32_APICBASE) of its VCPU. x2APIC stores APIC ID in
1856 the APIC_ID register (bytes 32-35). xAPIC only allows an 8-bit APIC ID
1857 which is stored in bits 31-24 of the APIC register, or equivalently in
1858 byte 35 of struct kvm_lapic_state's regs field. KVM_GET_LAPIC must then
1859 be called after MSR_IA32_APICBASE has been set with KVM_SET_MSR.
1861 If KVM_X2APIC_API_USE_32BIT_IDS feature is disabled, struct kvm_lapic_state
1862 always uses xAPIC format.
1868 :Capability: KVM_CAP_IRQCHIP
1871 :Parameters: struct kvm_lapic_state (in)
1872 :Returns: 0 on success, -1 on error
1876 #define KVM_APIC_REG_SIZE 0x400
1877 struct kvm_lapic_state {
1878 char regs[KVM_APIC_REG_SIZE];
1881 Copies the input argument into the Local APIC registers. The data format
1882 and layout are the same as documented in the architecture manual.
1884 The format of the APIC ID register (bytes 32-35 of struct kvm_lapic_state's
1885 regs field) depends on the state of the KVM_CAP_X2APIC_API capability.
1886 See the note in KVM_GET_LAPIC.
1892 :Capability: KVM_CAP_IOEVENTFD
1895 :Parameters: struct kvm_ioeventfd (in)
1896 :Returns: 0 on success, !0 on error
1898 This ioctl attaches or detaches an ioeventfd to a legal pio/mmio address
1899 within the guest. A guest write in the registered address will signal the
1900 provided event instead of triggering an exit.
1904 struct kvm_ioeventfd {
1906 __u64 addr; /* legal pio/mmio address */
1907 __u32 len; /* 0, 1, 2, 4, or 8 bytes */
1913 For the special case of virtio-ccw devices on s390, the ioevent is matched
1914 to a subchannel/virtqueue tuple instead.
1916 The following flags are defined::
1918 #define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)
1919 #define KVM_IOEVENTFD_FLAG_PIO (1 << kvm_ioeventfd_flag_nr_pio)
1920 #define KVM_IOEVENTFD_FLAG_DEASSIGN (1 << kvm_ioeventfd_flag_nr_deassign)
1921 #define KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY \
1922 (1 << kvm_ioeventfd_flag_nr_virtio_ccw_notify)
1924 If datamatch flag is set, the event will be signaled only if the written value
1925 to the registered address is equal to datamatch in struct kvm_ioeventfd.
1927 For virtio-ccw devices, addr contains the subchannel id and datamatch the
1930 With KVM_CAP_IOEVENTFD_ANY_LENGTH, a zero length ioeventfd is allowed, and
1931 the kernel will ignore the length of guest write and may get a faster vmexit.
1932 The speedup may only apply to specific architectures, but the ioeventfd will
1938 :Capability: KVM_CAP_SW_TLB
1941 :Parameters: struct kvm_dirty_tlb (in)
1942 :Returns: 0 on success, -1 on error
1946 struct kvm_dirty_tlb {
1951 This must be called whenever userspace has changed an entry in the shared
1952 TLB, prior to calling KVM_RUN on the associated vcpu.
1954 The "bitmap" field is the userspace address of an array. This array
1955 consists of a number of bits, equal to the total number of TLB entries as
1956 determined by the last successful call to KVM_CONFIG_TLB, rounded up to the
1957 nearest multiple of 64.
1959 Each bit corresponds to one TLB entry, ordered the same as in the shared TLB
1962 The array is little-endian: the bit 0 is the least significant bit of the
1963 first byte, bit 8 is the least significant bit of the second byte, etc.
1964 This avoids any complications with differing word sizes.
1966 The "num_dirty" field is a performance hint for KVM to determine whether it
1967 should skip processing the bitmap and just invalidate everything. It must
1968 be set to the number of set bits in the bitmap.
1971 4.62 KVM_CREATE_SPAPR_TCE
1972 -------------------------
1974 :Capability: KVM_CAP_SPAPR_TCE
1975 :Architectures: powerpc
1977 :Parameters: struct kvm_create_spapr_tce (in)
1978 :Returns: file descriptor for manipulating the created TCE table
1980 This creates a virtual TCE (translation control entry) table, which
1981 is an IOMMU for PAPR-style virtual I/O. It is used to translate
1982 logical addresses used in virtual I/O into guest physical addresses,
1983 and provides a scatter/gather capability for PAPR virtual I/O.
1987 /* for KVM_CAP_SPAPR_TCE */
1988 struct kvm_create_spapr_tce {
1993 The liobn field gives the logical IO bus number for which to create a
1994 TCE table. The window_size field specifies the size of the DMA window
1995 which this TCE table will translate - the table will contain one 64
1996 bit TCE entry for every 4kiB of the DMA window.
1998 When the guest issues an H_PUT_TCE hcall on a liobn for which a TCE
1999 table has been created using this ioctl(), the kernel will handle it
2000 in real mode, updating the TCE table. H_PUT_TCE calls for other
2001 liobns will cause a vm exit and must be handled by userspace.
2003 The return value is a file descriptor which can be passed to mmap(2)
2004 to map the created TCE table into userspace. This lets userspace read
2005 the entries written by kernel-handled H_PUT_TCE calls, and also lets
2006 userspace update the TCE table directly which is useful in some
2010 4.63 KVM_ALLOCATE_RMA
2011 ---------------------
2013 :Capability: KVM_CAP_PPC_RMA
2014 :Architectures: powerpc
2016 :Parameters: struct kvm_allocate_rma (out)
2017 :Returns: file descriptor for mapping the allocated RMA
2019 This allocates a Real Mode Area (RMA) from the pool allocated at boot
2020 time by the kernel. An RMA is a physically-contiguous, aligned region
2021 of memory used on older POWER processors to provide the memory which
2022 will be accessed by real-mode (MMU off) accesses in a KVM guest.
2023 POWER processors support a set of sizes for the RMA that usually
2024 includes 64MB, 128MB, 256MB and some larger powers of two.
2028 /* for KVM_ALLOCATE_RMA */
2029 struct kvm_allocate_rma {
2033 The return value is a file descriptor which can be passed to mmap(2)
2034 to map the allocated RMA into userspace. The mapped area can then be
2035 passed to the KVM_SET_USER_MEMORY_REGION ioctl to establish it as the
2036 RMA for a virtual machine. The size of the RMA in bytes (which is
2037 fixed at host kernel boot time) is returned in the rma_size field of
2038 the argument structure.
2040 The KVM_CAP_PPC_RMA capability is 1 or 2 if the KVM_ALLOCATE_RMA ioctl
2041 is supported; 2 if the processor requires all virtual machines to have
2042 an RMA, or 1 if the processor can use an RMA but doesn't require it,
2043 because it supports the Virtual RMA (VRMA) facility.
2049 :Capability: KVM_CAP_USER_NMI
2053 :Returns: 0 on success, -1 on error
2055 Queues an NMI on the thread's vcpu. Note this is well defined only
2056 when KVM_CREATE_IRQCHIP has not been called, since this is an interface
2057 between the virtual cpu core and virtual local APIC. After KVM_CREATE_IRQCHIP
2058 has been called, this interface is completely emulated within the kernel.
2060 To use this to emulate the LINT1 input with KVM_CREATE_IRQCHIP, use the
2061 following algorithm:
2064 - read the local APIC's state (KVM_GET_LAPIC)
2065 - check whether changing LINT1 will queue an NMI (see the LVT entry for LINT1)
2066 - if so, issue KVM_NMI
2069 Some guests configure the LINT1 NMI input to cause a panic, aiding in
2073 4.65 KVM_S390_UCAS_MAP
2074 ----------------------
2076 :Capability: KVM_CAP_S390_UCONTROL
2077 :Architectures: s390
2079 :Parameters: struct kvm_s390_ucas_mapping (in)
2080 :Returns: 0 in case of success
2082 The parameter is defined like this::
2084 struct kvm_s390_ucas_mapping {
2090 This ioctl maps the memory at "user_addr" with the length "length" to
2091 the vcpu's address space starting at "vcpu_addr". All parameters need to
2092 be aligned by 1 megabyte.
2095 4.66 KVM_S390_UCAS_UNMAP
2096 ------------------------
2098 :Capability: KVM_CAP_S390_UCONTROL
2099 :Architectures: s390
2101 :Parameters: struct kvm_s390_ucas_mapping (in)
2102 :Returns: 0 in case of success
2104 The parameter is defined like this::
2106 struct kvm_s390_ucas_mapping {
2112 This ioctl unmaps the memory in the vcpu's address space starting at
2113 "vcpu_addr" with the length "length". The field "user_addr" is ignored.
2114 All parameters need to be aligned by 1 megabyte.
2117 4.67 KVM_S390_VCPU_FAULT
2118 ------------------------
2120 :Capability: KVM_CAP_S390_UCONTROL
2121 :Architectures: s390
2123 :Parameters: vcpu absolute address (in)
2124 :Returns: 0 in case of success
2126 This call creates a page table entry on the virtual cpu's address space
2127 (for user controlled virtual machines) or the virtual machine's address
2128 space (for regular virtual machines). This only works for minor faults,
2129 thus it's recommended to access subject memory page via the user page
2130 table upfront. This is useful to handle validity intercepts for user
2131 controlled virtual machines to fault in the virtual cpu's lowcore pages
2132 prior to calling the KVM_RUN ioctl.
2135 4.68 KVM_SET_ONE_REG
2136 --------------------
2138 :Capability: KVM_CAP_ONE_REG
2141 :Parameters: struct kvm_one_reg (in)
2142 :Returns: 0 on success, negative value on failure
2146 ====== ============================================================
2147 Â ENOENT Â Â no such register
2148 Â EINVAL Â Â invalid register ID, or no such register or used with VMs in
2149 protected virtualization mode on s390
2150 Â EPERM Â Â Â (arm64) register access not allowed before vcpu finalization
2151 ====== ============================================================
2153 (These error codes are indicative only: do not rely on a specific error
2154 code being returned in a specific situation.)
2158 struct kvm_one_reg {
2163 Using this ioctl, a single vcpu register can be set to a specific value
2164 defined by user space with the passed in struct kvm_one_reg, where id
2165 refers to the register identifier as described below and addr is a pointer
2166 to a variable with the respective size. There can be architecture agnostic
2167 and architecture specific registers. Each have their own range of operation
2168 and their own constants and width. To keep track of the implemented
2169 registers, find a list below:
2171 ======= =============================== ============
2172 Arch Register Width (bits)
2173 ======= =============================== ============
2174 PPC KVM_REG_PPC_HIOR 64
2175 PPC KVM_REG_PPC_IAC1 64
2176 PPC KVM_REG_PPC_IAC2 64
2177 PPC KVM_REG_PPC_IAC3 64
2178 PPC KVM_REG_PPC_IAC4 64
2179 PPC KVM_REG_PPC_DAC1 64
2180 PPC KVM_REG_PPC_DAC2 64
2181 PPC KVM_REG_PPC_DABR 64
2182 PPC KVM_REG_PPC_DSCR 64
2183 PPC KVM_REG_PPC_PURR 64
2184 PPC KVM_REG_PPC_SPURR 64
2185 PPC KVM_REG_PPC_DAR 64
2186 PPC KVM_REG_PPC_DSISR 32
2187 PPC KVM_REG_PPC_AMR 64
2188 PPC KVM_REG_PPC_UAMOR 64
2189 PPC KVM_REG_PPC_MMCR0 64
2190 PPC KVM_REG_PPC_MMCR1 64
2191 PPC KVM_REG_PPC_MMCRA 64
2192 PPC KVM_REG_PPC_MMCR2 64
2193 PPC KVM_REG_PPC_MMCRS 64
2194 PPC KVM_REG_PPC_MMCR3 64
2195 PPC KVM_REG_PPC_SIAR 64
2196 PPC KVM_REG_PPC_SDAR 64
2197 PPC KVM_REG_PPC_SIER 64
2198 PPC KVM_REG_PPC_SIER2 64
2199 PPC KVM_REG_PPC_SIER3 64
2200 PPC KVM_REG_PPC_PMC1 32
2201 PPC KVM_REG_PPC_PMC2 32
2202 PPC KVM_REG_PPC_PMC3 32
2203 PPC KVM_REG_PPC_PMC4 32
2204 PPC KVM_REG_PPC_PMC5 32
2205 PPC KVM_REG_PPC_PMC6 32
2206 PPC KVM_REG_PPC_PMC7 32
2207 PPC KVM_REG_PPC_PMC8 32
2208 PPC KVM_REG_PPC_FPR0 64
2210 PPC KVM_REG_PPC_FPR31 64
2211 PPC KVM_REG_PPC_VR0 128
2213 PPC KVM_REG_PPC_VR31 128
2214 PPC KVM_REG_PPC_VSR0 128
2216 PPC KVM_REG_PPC_VSR31 128
2217 PPC KVM_REG_PPC_FPSCR 64
2218 PPC KVM_REG_PPC_VSCR 32
2219 PPC KVM_REG_PPC_VPA_ADDR 64
2220 PPC KVM_REG_PPC_VPA_SLB 128
2221 PPC KVM_REG_PPC_VPA_DTL 128
2222 PPC KVM_REG_PPC_EPCR 32
2223 PPC KVM_REG_PPC_EPR 32
2224 PPC KVM_REG_PPC_TCR 32
2225 PPC KVM_REG_PPC_TSR 32
2226 PPC KVM_REG_PPC_OR_TSR 32
2227 PPC KVM_REG_PPC_CLEAR_TSR 32
2228 PPC KVM_REG_PPC_MAS0 32
2229 PPC KVM_REG_PPC_MAS1 32
2230 PPC KVM_REG_PPC_MAS2 64
2231 PPC KVM_REG_PPC_MAS7_3 64
2232 PPC KVM_REG_PPC_MAS4 32
2233 PPC KVM_REG_PPC_MAS6 32
2234 PPC KVM_REG_PPC_MMUCFG 32
2235 PPC KVM_REG_PPC_TLB0CFG 32
2236 PPC KVM_REG_PPC_TLB1CFG 32
2237 PPC KVM_REG_PPC_TLB2CFG 32
2238 PPC KVM_REG_PPC_TLB3CFG 32
2239 PPC KVM_REG_PPC_TLB0PS 32
2240 PPC KVM_REG_PPC_TLB1PS 32
2241 PPC KVM_REG_PPC_TLB2PS 32
2242 PPC KVM_REG_PPC_TLB3PS 32
2243 PPC KVM_REG_PPC_EPTCFG 32
2244 PPC KVM_REG_PPC_ICP_STATE 64
2245 PPC KVM_REG_PPC_VP_STATE 128
2246 PPC KVM_REG_PPC_TB_OFFSET 64
2247 PPC KVM_REG_PPC_SPMC1 32
2248 PPC KVM_REG_PPC_SPMC2 32
2249 PPC KVM_REG_PPC_IAMR 64
2250 PPC KVM_REG_PPC_TFHAR 64
2251 PPC KVM_REG_PPC_TFIAR 64
2252 PPC KVM_REG_PPC_TEXASR 64
2253 PPC KVM_REG_PPC_FSCR 64
2254 PPC KVM_REG_PPC_PSPB 32
2255 PPC KVM_REG_PPC_EBBHR 64
2256 PPC KVM_REG_PPC_EBBRR 64
2257 PPC KVM_REG_PPC_BESCR 64
2258 PPC KVM_REG_PPC_TAR 64
2259 PPC KVM_REG_PPC_DPDES 64
2260 PPC KVM_REG_PPC_DAWR 64
2261 PPC KVM_REG_PPC_DAWRX 64
2262 PPC KVM_REG_PPC_CIABR 64
2263 PPC KVM_REG_PPC_IC 64
2264 PPC KVM_REG_PPC_VTB 64
2265 PPC KVM_REG_PPC_CSIGR 64
2266 PPC KVM_REG_PPC_TACR 64
2267 PPC KVM_REG_PPC_TCSCR 64
2268 PPC KVM_REG_PPC_PID 64
2269 PPC KVM_REG_PPC_ACOP 64
2270 PPC KVM_REG_PPC_VRSAVE 32
2271 PPC KVM_REG_PPC_LPCR 32
2272 PPC KVM_REG_PPC_LPCR_64 64
2273 PPC KVM_REG_PPC_PPR 64
2274 PPC KVM_REG_PPC_ARCH_COMPAT 32
2275 PPC KVM_REG_PPC_DABRX 32
2276 PPC KVM_REG_PPC_WORT 64
2277 PPC KVM_REG_PPC_SPRG9 64
2278 PPC KVM_REG_PPC_DBSR 32
2279 PPC KVM_REG_PPC_TIDR 64
2280 PPC KVM_REG_PPC_PSSCR 64
2281 PPC KVM_REG_PPC_DEC_EXPIRY 64
2282 PPC KVM_REG_PPC_PTCR 64
2283 PPC KVM_REG_PPC_DAWR1 64
2284 PPC KVM_REG_PPC_DAWRX1 64
2285 PPC KVM_REG_PPC_TM_GPR0 64
2287 PPC KVM_REG_PPC_TM_GPR31 64
2288 PPC KVM_REG_PPC_TM_VSR0 128
2290 PPC KVM_REG_PPC_TM_VSR63 128
2291 PPC KVM_REG_PPC_TM_CR 64
2292 PPC KVM_REG_PPC_TM_LR 64
2293 PPC KVM_REG_PPC_TM_CTR 64
2294 PPC KVM_REG_PPC_TM_FPSCR 64
2295 PPC KVM_REG_PPC_TM_AMR 64
2296 PPC KVM_REG_PPC_TM_PPR 64
2297 PPC KVM_REG_PPC_TM_VRSAVE 64
2298 PPC KVM_REG_PPC_TM_VSCR 32
2299 PPC KVM_REG_PPC_TM_DSCR 64
2300 PPC KVM_REG_PPC_TM_TAR 64
2301 PPC KVM_REG_PPC_TM_XER 64
2303 MIPS KVM_REG_MIPS_R0 64
2305 MIPS KVM_REG_MIPS_R31 64
2306 MIPS KVM_REG_MIPS_HI 64
2307 MIPS KVM_REG_MIPS_LO 64
2308 MIPS KVM_REG_MIPS_PC 64
2309 MIPS KVM_REG_MIPS_CP0_INDEX 32
2310 MIPS KVM_REG_MIPS_CP0_ENTRYLO0 64
2311 MIPS KVM_REG_MIPS_CP0_ENTRYLO1 64
2312 MIPS KVM_REG_MIPS_CP0_CONTEXT 64
2313 MIPS KVM_REG_MIPS_CP0_CONTEXTCONFIG 32
2314 MIPS KVM_REG_MIPS_CP0_USERLOCAL 64
2315 MIPS KVM_REG_MIPS_CP0_XCONTEXTCONFIG 64
2316 MIPS KVM_REG_MIPS_CP0_PAGEMASK 32
2317 MIPS KVM_REG_MIPS_CP0_PAGEGRAIN 32
2318 MIPS KVM_REG_MIPS_CP0_SEGCTL0 64
2319 MIPS KVM_REG_MIPS_CP0_SEGCTL1 64
2320 MIPS KVM_REG_MIPS_CP0_SEGCTL2 64
2321 MIPS KVM_REG_MIPS_CP0_PWBASE 64
2322 MIPS KVM_REG_MIPS_CP0_PWFIELD 64
2323 MIPS KVM_REG_MIPS_CP0_PWSIZE 64
2324 MIPS KVM_REG_MIPS_CP0_WIRED 32
2325 MIPS KVM_REG_MIPS_CP0_PWCTL 32
2326 MIPS KVM_REG_MIPS_CP0_HWRENA 32
2327 MIPS KVM_REG_MIPS_CP0_BADVADDR 64
2328 MIPS KVM_REG_MIPS_CP0_BADINSTR 32
2329 MIPS KVM_REG_MIPS_CP0_BADINSTRP 32
2330 MIPS KVM_REG_MIPS_CP0_COUNT 32
2331 MIPS KVM_REG_MIPS_CP0_ENTRYHI 64
2332 MIPS KVM_REG_MIPS_CP0_COMPARE 32
2333 MIPS KVM_REG_MIPS_CP0_STATUS 32
2334 MIPS KVM_REG_MIPS_CP0_INTCTL 32
2335 MIPS KVM_REG_MIPS_CP0_CAUSE 32
2336 MIPS KVM_REG_MIPS_CP0_EPC 64
2337 MIPS KVM_REG_MIPS_CP0_PRID 32
2338 MIPS KVM_REG_MIPS_CP0_EBASE 64
2339 MIPS KVM_REG_MIPS_CP0_CONFIG 32
2340 MIPS KVM_REG_MIPS_CP0_CONFIG1 32
2341 MIPS KVM_REG_MIPS_CP0_CONFIG2 32
2342 MIPS KVM_REG_MIPS_CP0_CONFIG3 32
2343 MIPS KVM_REG_MIPS_CP0_CONFIG4 32
2344 MIPS KVM_REG_MIPS_CP0_CONFIG5 32
2345 MIPS KVM_REG_MIPS_CP0_CONFIG7 32
2346 MIPS KVM_REG_MIPS_CP0_XCONTEXT 64
2347 MIPS KVM_REG_MIPS_CP0_ERROREPC 64
2348 MIPS KVM_REG_MIPS_CP0_KSCRATCH1 64
2349 MIPS KVM_REG_MIPS_CP0_KSCRATCH2 64
2350 MIPS KVM_REG_MIPS_CP0_KSCRATCH3 64
2351 MIPS KVM_REG_MIPS_CP0_KSCRATCH4 64
2352 MIPS KVM_REG_MIPS_CP0_KSCRATCH5 64
2353 MIPS KVM_REG_MIPS_CP0_KSCRATCH6 64
2354 MIPS KVM_REG_MIPS_CP0_MAAR(0..63) 64
2355 MIPS KVM_REG_MIPS_COUNT_CTL 64
2356 MIPS KVM_REG_MIPS_COUNT_RESUME 64
2357 MIPS KVM_REG_MIPS_COUNT_HZ 64
2358 MIPS KVM_REG_MIPS_FPR_32(0..31) 32
2359 MIPS KVM_REG_MIPS_FPR_64(0..31) 64
2360 MIPS KVM_REG_MIPS_VEC_128(0..31) 128
2361 MIPS KVM_REG_MIPS_FCR_IR 32
2362 MIPS KVM_REG_MIPS_FCR_CSR 32
2363 MIPS KVM_REG_MIPS_MSA_IR 32
2364 MIPS KVM_REG_MIPS_MSA_CSR 32
2365 ======= =============================== ============
2367 ARM registers are mapped using the lower 32 bits. The upper 16 of that
2368 is the register group type, or coprocessor number:
2370 ARM core registers have the following id bit patterns::
2372 0x4020 0000 0010 <index into the kvm_regs struct:16>
2374 ARM 32-bit CP15 registers have the following id bit patterns::
2376 0x4020 0000 000F <zero:1> <crn:4> <crm:4> <opc1:4> <opc2:3>
2378 ARM 64-bit CP15 registers have the following id bit patterns::
2380 0x4030 0000 000F <zero:1> <zero:4> <crm:4> <opc1:4> <zero:3>
2382 ARM CCSIDR registers are demultiplexed by CSSELR value::
2384 0x4020 0000 0011 00 <csselr:8>
2386 ARM 32-bit VFP control registers have the following id bit patterns::
2388 0x4020 0000 0012 1 <regno:12>
2390 ARM 64-bit FP registers have the following id bit patterns::
2392 0x4030 0000 0012 0 <regno:12>
2394 ARM firmware pseudo-registers have the following bit pattern::
2396 0x4030 0000 0014 <regno:16>
2399 arm64 registers are mapped using the lower 32 bits. The upper 16 of
2400 that is the register group type, or coprocessor number:
2402 arm64 core/FP-SIMD registers have the following id bit patterns. Note
2403 that the size of the access is variable, as the kvm_regs structure
2404 contains elements ranging from 32 to 128 bits. The index is a 32bit
2405 value in the kvm_regs structure seen as a 32bit array::
2407 0x60x0 0000 0010 <index into the kvm_regs struct:16>
2411 ======================= ========= ===== =======================================
2412 Encoding Register Bits kvm_regs member
2413 ======================= ========= ===== =======================================
2414 0x6030 0000 0010 0000 X0 64 regs.regs[0]
2415 0x6030 0000 0010 0002 X1 64 regs.regs[1]
2417 0x6030 0000 0010 003c X30 64 regs.regs[30]
2418 0x6030 0000 0010 003e SP 64 regs.sp
2419 0x6030 0000 0010 0040 PC 64 regs.pc
2420 0x6030 0000 0010 0042 PSTATE 64 regs.pstate
2421 0x6030 0000 0010 0044 SP_EL1 64 sp_el1
2422 0x6030 0000 0010 0046 ELR_EL1 64 elr_el1
2423 0x6030 0000 0010 0048 SPSR_EL1 64 spsr[KVM_SPSR_EL1] (alias SPSR_SVC)
2424 0x6030 0000 0010 004a SPSR_ABT 64 spsr[KVM_SPSR_ABT]
2425 0x6030 0000 0010 004c SPSR_UND 64 spsr[KVM_SPSR_UND]
2426 0x6030 0000 0010 004e SPSR_IRQ 64 spsr[KVM_SPSR_IRQ]
2427 0x6060 0000 0010 0050 SPSR_FIQ 64 spsr[KVM_SPSR_FIQ]
2428 0x6040 0000 0010 0054 V0 128 fp_regs.vregs[0] [1]_
2429 0x6040 0000 0010 0058 V1 128 fp_regs.vregs[1] [1]_
2431 0x6040 0000 0010 00d0 V31 128 fp_regs.vregs[31] [1]_
2432 0x6020 0000 0010 00d4 FPSR 32 fp_regs.fpsr
2433 0x6020 0000 0010 00d5 FPCR 32 fp_regs.fpcr
2434 ======================= ========= ===== =======================================
2436 .. [1] These encodings are not accepted for SVE-enabled vcpus. See
2439 The equivalent register content can be accessed via bits [127:0] of
2440 the corresponding SVE Zn registers instead for vcpus that have SVE
2441 enabled (see below).
2443 arm64 CCSIDR registers are demultiplexed by CSSELR value::
2445 0x6020 0000 0011 00 <csselr:8>
2447 arm64 system registers have the following id bit patterns::
2449 0x6030 0000 0013 <op0:2> <op1:3> <crn:4> <crm:4> <op2:3>
2453 Two system register IDs do not follow the specified pattern. These
2454 are KVM_REG_ARM_TIMER_CVAL and KVM_REG_ARM_TIMER_CNT, which map to
2455 system registers CNTV_CVAL_EL0 and CNTVCT_EL0 respectively. These
2456 two had their values accidentally swapped, which means TIMER_CVAL is
2457 derived from the register encoding for CNTVCT_EL0 and TIMER_CNT is
2458 derived from the register encoding for CNTV_CVAL_EL0. As this is
2459 API, it must remain this way.
2461 arm64 firmware pseudo-registers have the following bit pattern::
2463 0x6030 0000 0014 <regno:16>
2465 arm64 SVE registers have the following bit patterns::
2467 0x6080 0000 0015 00 <n:5> <slice:5> Zn bits[2048*slice + 2047 : 2048*slice]
2468 0x6050 0000 0015 04 <n:4> <slice:5> Pn bits[256*slice + 255 : 256*slice]
2469 0x6050 0000 0015 060 <slice:5> FFR bits[256*slice + 255 : 256*slice]
2470 0x6060 0000 0015 ffff KVM_REG_ARM64_SVE_VLS pseudo-register
2472 Access to register IDs where 2048 * slice >= 128 * max_vq will fail with
2473 ENOENT. max_vq is the vcpu's maximum supported vector length in 128-bit
2474 quadwords: see [2]_ below.
2476 These registers are only accessible on vcpus for which SVE is enabled.
2477 See KVM_ARM_VCPU_INIT for details.
2479 In addition, except for KVM_REG_ARM64_SVE_VLS, these registers are not
2480 accessible until the vcpu's SVE configuration has been finalized
2481 using KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE). See KVM_ARM_VCPU_INIT
2482 and KVM_ARM_VCPU_FINALIZE for more information about this procedure.
2484 KVM_REG_ARM64_SVE_VLS is a pseudo-register that allows the set of vector
2485 lengths supported by the vcpu to be discovered and configured by
2486 userspace. When transferred to or from user memory via KVM_GET_ONE_REG
2487 or KVM_SET_ONE_REG, the value of this register is of type
2488 __u64[KVM_ARM64_SVE_VLS_WORDS], and encodes the set of vector lengths as
2491 __u64 vector_lengths[KVM_ARM64_SVE_VLS_WORDS];
2493 if (vq >= SVE_VQ_MIN && vq <= SVE_VQ_MAX &&
2494 ((vector_lengths[(vq - KVM_ARM64_SVE_VQ_MIN) / 64] >>
2495 ((vq - KVM_ARM64_SVE_VQ_MIN) % 64)) & 1))
2496 /* Vector length vq * 16 bytes supported */
2498 /* Vector length vq * 16 bytes not supported */
2500 .. [2] The maximum value vq for which the above condition is true is
2501 max_vq. This is the maximum vector length available to the guest on
2502 this vcpu, and determines which register slices are visible through
2503 this ioctl interface.
2505 (See Documentation/arm64/sve.rst for an explanation of the "vq"
2508 KVM_REG_ARM64_SVE_VLS is only accessible after KVM_ARM_VCPU_INIT.
2509 KVM_ARM_VCPU_INIT initialises it to the best set of vector lengths that
2512 Userspace may subsequently modify it if desired until the vcpu's SVE
2513 configuration is finalized using KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE).
2515 Apart from simply removing all vector lengths from the host set that
2516 exceed some value, support for arbitrarily chosen sets of vector lengths
2517 is hardware-dependent and may not be available. Attempting to configure
2518 an invalid set of vector lengths via KVM_SET_ONE_REG will fail with
2521 After the vcpu's SVE configuration is finalized, further attempts to
2522 write this register will fail with EPERM.
2525 MIPS registers are mapped using the lower 32 bits. The upper 16 of that is
2526 the register group type:
2528 MIPS core registers (see above) have the following id bit patterns::
2530 0x7030 0000 0000 <reg:16>
2532 MIPS CP0 registers (see KVM_REG_MIPS_CP0_* above) have the following id bit
2533 patterns depending on whether they're 32-bit or 64-bit registers::
2535 0x7020 0000 0001 00 <reg:5> <sel:3> (32-bit)
2536 0x7030 0000 0001 00 <reg:5> <sel:3> (64-bit)
2538 Note: KVM_REG_MIPS_CP0_ENTRYLO0 and KVM_REG_MIPS_CP0_ENTRYLO1 are the MIPS64
2539 versions of the EntryLo registers regardless of the word size of the host
2540 hardware, host kernel, guest, and whether XPA is present in the guest, i.e.
2541 with the RI and XI bits (if they exist) in bits 63 and 62 respectively, and
2542 the PFNX field starting at bit 30.
2544 MIPS MAARs (see KVM_REG_MIPS_CP0_MAAR(*) above) have the following id bit
2547 0x7030 0000 0001 01 <reg:8>
2549 MIPS KVM control registers (see above) have the following id bit patterns::
2551 0x7030 0000 0002 <reg:16>
2553 MIPS FPU registers (see KVM_REG_MIPS_FPR_{32,64}() above) have the following
2554 id bit patterns depending on the size of the register being accessed. They are
2555 always accessed according to the current guest FPU mode (Status.FR and
2556 Config5.FRE), i.e. as the guest would see them, and they become unpredictable
2557 if the guest FPU mode is changed. MIPS SIMD Architecture (MSA) vector
2558 registers (see KVM_REG_MIPS_VEC_128() above) have similar patterns as they
2559 overlap the FPU registers::
2561 0x7020 0000 0003 00 <0:3> <reg:5> (32-bit FPU registers)
2562 0x7030 0000 0003 00 <0:3> <reg:5> (64-bit FPU registers)
2563 0x7040 0000 0003 00 <0:3> <reg:5> (128-bit MSA vector registers)
2565 MIPS FPU control registers (see KVM_REG_MIPS_FCR_{IR,CSR} above) have the
2566 following id bit patterns::
2568 0x7020 0000 0003 01 <0:3> <reg:5>
2570 MIPS MSA control registers (see KVM_REG_MIPS_MSA_{IR,CSR} above) have the
2571 following id bit patterns::
2573 0x7020 0000 0003 02 <0:3> <reg:5>
2576 4.69 KVM_GET_ONE_REG
2577 --------------------
2579 :Capability: KVM_CAP_ONE_REG
2582 :Parameters: struct kvm_one_reg (in and out)
2583 :Returns: 0 on success, negative value on failure
2587 ======== ============================================================
2588 Â ENOENT Â Â no such register
2589 Â EINVAL Â Â invalid register ID, or no such register or used with VMs in
2590 protected virtualization mode on s390
2591 Â EPERM Â Â Â (arm64) register access not allowed before vcpu finalization
2592 ======== ============================================================
2594 (These error codes are indicative only: do not rely on a specific error
2595 code being returned in a specific situation.)
2597 This ioctl allows to receive the value of a single register implemented
2598 in a vcpu. The register to read is indicated by the "id" field of the
2599 kvm_one_reg struct passed in. On success, the register value can be found
2600 at the memory location pointed to by "addr".
2602 The list of registers accessible using this interface is identical to the
2606 4.70 KVM_KVMCLOCK_CTRL
2607 ----------------------
2609 :Capability: KVM_CAP_KVMCLOCK_CTRL
2610 :Architectures: Any that implement pvclocks (currently x86 only)
2613 :Returns: 0 on success, -1 on error
2615 This ioctl sets a flag accessible to the guest indicating that the specified
2616 vCPU has been paused by the host userspace.
2618 The host will set a flag in the pvclock structure that is checked from the
2619 soft lockup watchdog. The flag is part of the pvclock structure that is
2620 shared between guest and host, specifically the second bit of the flags
2621 field of the pvclock_vcpu_time_info structure. It will be set exclusively by
2622 the host and read/cleared exclusively by the guest. The guest operation of
2623 checking and clearing the flag must be an atomic operation so
2624 load-link/store-conditional, or equivalent must be used. There are two cases
2625 where the guest will clear the flag: when the soft lockup watchdog timer resets
2626 itself or when a soft lockup is detected. This ioctl can be called any time
2627 after pausing the vcpu, but before it is resumed.
2633 :Capability: KVM_CAP_SIGNAL_MSI
2634 :Architectures: x86 arm arm64
2636 :Parameters: struct kvm_msi (in)
2637 :Returns: >0 on delivery, 0 if guest blocked the MSI, and -1 on error
2639 Directly inject a MSI message. Only valid with in-kernel irqchip that handles
2654 KVM_MSI_VALID_DEVID: devid contains a valid value. The per-VM
2655 KVM_CAP_MSI_DEVID capability advertises the requirement to provide
2656 the device ID. If this capability is not available, userspace
2657 should never set the KVM_MSI_VALID_DEVID flag as the ioctl might fail.
2659 If KVM_MSI_VALID_DEVID is set, devid contains a unique device identifier
2660 for the device that wrote the MSI message. For PCI, this is usually a
2661 BFD identifier in the lower 16 bits.
2663 On x86, address_hi is ignored unless the KVM_X2APIC_API_USE_32BIT_IDS
2664 feature of KVM_CAP_X2APIC_API capability is enabled. If it is enabled,
2665 address_hi bits 31-8 provide bits 31-8 of the destination id. Bits 7-0 of
2666 address_hi must be zero.
2669 4.71 KVM_CREATE_PIT2
2670 --------------------
2672 :Capability: KVM_CAP_PIT2
2675 :Parameters: struct kvm_pit_config (in)
2676 :Returns: 0 on success, -1 on error
2678 Creates an in-kernel device model for the i8254 PIT. This call is only valid
2679 after enabling in-kernel irqchip support via KVM_CREATE_IRQCHIP. The following
2680 parameters have to be passed::
2682 struct kvm_pit_config {
2689 #define KVM_PIT_SPEAKER_DUMMY 1 /* emulate speaker port stub */
2691 PIT timer interrupts may use a per-VM kernel thread for injection. If it
2692 exists, this thread will have a name of the following pattern::
2694 kvm-pit/<owner-process-pid>
2696 When running a guest with elevated priorities, the scheduling parameters of
2697 this thread may have to be adjusted accordingly.
2699 This IOCTL replaces the obsolete KVM_CREATE_PIT.
2705 :Capability: KVM_CAP_PIT_STATE2
2708 :Parameters: struct kvm_pit_state2 (out)
2709 :Returns: 0 on success, -1 on error
2711 Retrieves the state of the in-kernel PIT model. Only valid after
2712 KVM_CREATE_PIT2. The state is returned in the following structure::
2714 struct kvm_pit_state2 {
2715 struct kvm_pit_channel_state channels[3];
2722 /* disable PIT in HPET legacy mode */
2723 #define KVM_PIT_FLAGS_HPET_LEGACY 0x00000001
2725 This IOCTL replaces the obsolete KVM_GET_PIT.
2731 :Capability: KVM_CAP_PIT_STATE2
2734 :Parameters: struct kvm_pit_state2 (in)
2735 :Returns: 0 on success, -1 on error
2737 Sets the state of the in-kernel PIT model. Only valid after KVM_CREATE_PIT2.
2738 See KVM_GET_PIT2 for details on struct kvm_pit_state2.
2740 This IOCTL replaces the obsolete KVM_SET_PIT.
2743 4.74 KVM_PPC_GET_SMMU_INFO
2744 --------------------------
2746 :Capability: KVM_CAP_PPC_GET_SMMU_INFO
2747 :Architectures: powerpc
2750 :Returns: 0 on success, -1 on error
2752 This populates and returns a structure describing the features of
2753 the "Server" class MMU emulation supported by KVM.
2754 This can in turn be used by userspace to generate the appropriate
2755 device-tree properties for the guest operating system.
2757 The structure contains some global information, followed by an
2758 array of supported segment page sizes::
2760 struct kvm_ppc_smmu_info {
2764 struct kvm_ppc_one_seg_page_size sps[KVM_PPC_PAGE_SIZES_MAX_SZ];
2767 The supported flags are:
2769 - KVM_PPC_PAGE_SIZES_REAL:
2770 When that flag is set, guest page sizes must "fit" the backing
2771 store page sizes. When not set, any page size in the list can
2772 be used regardless of how they are backed by userspace.
2774 - KVM_PPC_1T_SEGMENTS
2775 The emulated MMU supports 1T segments in addition to the
2779 This flag indicates that HPT guests are not supported by KVM,
2780 thus all guests must use radix MMU mode.
2782 The "slb_size" field indicates how many SLB entries are supported
2784 The "sps" array contains 8 entries indicating the supported base
2785 page sizes for a segment in increasing order. Each entry is defined
2788 struct kvm_ppc_one_seg_page_size {
2789 __u32 page_shift; /* Base page shift of segment (or 0) */
2790 __u32 slb_enc; /* SLB encoding for BookS */
2791 struct kvm_ppc_one_page_size enc[KVM_PPC_PAGE_SIZES_MAX_SZ];
2794 An entry with a "page_shift" of 0 is unused. Because the array is
2795 organized in increasing order, a lookup can stop when encoutering
2798 The "slb_enc" field provides the encoding to use in the SLB for the
2799 page size. The bits are in positions such as the value can directly
2800 be OR'ed into the "vsid" argument of the slbmte instruction.
2802 The "enc" array is a list which for each of those segment base page
2803 size provides the list of supported actual page sizes (which can be
2804 only larger or equal to the base page size), along with the
2805 corresponding encoding in the hash PTE. Similarly, the array is
2806 8 entries sorted by increasing sizes and an entry with a "0" shift
2807 is an empty entry and a terminator::
2809 struct kvm_ppc_one_page_size {
2810 __u32 page_shift; /* Page shift (or 0) */
2811 __u32 pte_enc; /* Encoding in the HPTE (>>12) */
2814 The "pte_enc" field provides a value that can OR'ed into the hash
2815 PTE's RPN field (ie, it needs to be shifted left by 12 to OR it
2816 into the hash PTE second double word).
2821 :Capability: KVM_CAP_IRQFD
2822 :Architectures: x86 s390 arm arm64
2824 :Parameters: struct kvm_irqfd (in)
2825 :Returns: 0 on success, -1 on error
2827 Allows setting an eventfd to directly trigger a guest interrupt.
2828 kvm_irqfd.fd specifies the file descriptor to use as the eventfd and
2829 kvm_irqfd.gsi specifies the irqchip pin toggled by this event. When
2830 an event is triggered on the eventfd, an interrupt is injected into
2831 the guest using the specified gsi pin. The irqfd is removed using
2832 the KVM_IRQFD_FLAG_DEASSIGN flag, specifying both kvm_irqfd.fd
2835 With KVM_CAP_IRQFD_RESAMPLE, KVM_IRQFD supports a de-assert and notify
2836 mechanism allowing emulation of level-triggered, irqfd-based
2837 interrupts. When KVM_IRQFD_FLAG_RESAMPLE is set the user must pass an
2838 additional eventfd in the kvm_irqfd.resamplefd field. When operating
2839 in resample mode, posting of an interrupt through kvm_irq.fd asserts
2840 the specified gsi in the irqchip. When the irqchip is resampled, such
2841 as from an EOI, the gsi is de-asserted and the user is notified via
2842 kvm_irqfd.resamplefd. It is the user's responsibility to re-queue
2843 the interrupt if the device making use of it still requires service.
2844 Note that closing the resamplefd is not sufficient to disable the
2845 irqfd. The KVM_IRQFD_FLAG_RESAMPLE is only necessary on assignment
2846 and need not be specified with KVM_IRQFD_FLAG_DEASSIGN.
2848 On arm/arm64, gsi routing being supported, the following can happen:
2850 - in case no routing entry is associated to this gsi, injection fails
2851 - in case the gsi is associated to an irqchip routing entry,
2852 irqchip.pin + 32 corresponds to the injected SPI ID.
2853 - in case the gsi is associated to an MSI routing entry, the MSI
2854 message and device ID are translated into an LPI (support restricted
2855 to GICv3 ITS in-kernel emulation).
2857 4.76 KVM_PPC_ALLOCATE_HTAB
2858 --------------------------
2860 :Capability: KVM_CAP_PPC_ALLOC_HTAB
2861 :Architectures: powerpc
2863 :Parameters: Pointer to u32 containing hash table order (in/out)
2864 :Returns: 0 on success, -1 on error
2866 This requests the host kernel to allocate an MMU hash table for a
2867 guest using the PAPR paravirtualization interface. This only does
2868 anything if the kernel is configured to use the Book 3S HV style of
2869 virtualization. Otherwise the capability doesn't exist and the ioctl
2870 returns an ENOTTY error. The rest of this description assumes Book 3S
2873 There must be no vcpus running when this ioctl is called; if there
2874 are, it will do nothing and return an EBUSY error.
2876 The parameter is a pointer to a 32-bit unsigned integer variable
2877 containing the order (log base 2) of the desired size of the hash
2878 table, which must be between 18 and 46. On successful return from the
2879 ioctl, the value will not be changed by the kernel.
2881 If no hash table has been allocated when any vcpu is asked to run
2882 (with the KVM_RUN ioctl), the host kernel will allocate a
2883 default-sized hash table (16 MB).
2885 If this ioctl is called when a hash table has already been allocated,
2886 with a different order from the existing hash table, the existing hash
2887 table will be freed and a new one allocated. If this is ioctl is
2888 called when a hash table has already been allocated of the same order
2889 as specified, the kernel will clear out the existing hash table (zero
2890 all HPTEs). In either case, if the guest is using the virtualized
2891 real-mode area (VRMA) facility, the kernel will re-create the VMRA
2892 HPTEs on the next KVM_RUN of any vcpu.
2894 4.77 KVM_S390_INTERRUPT
2895 -----------------------
2898 :Architectures: s390
2899 :Type: vm ioctl, vcpu ioctl
2900 :Parameters: struct kvm_s390_interrupt (in)
2901 :Returns: 0 on success, -1 on error
2903 Allows to inject an interrupt to the guest. Interrupts can be floating
2904 (vm ioctl) or per cpu (vcpu ioctl), depending on the interrupt type.
2906 Interrupt parameters are passed via kvm_s390_interrupt::
2908 struct kvm_s390_interrupt {
2914 type can be one of the following:
2916 KVM_S390_SIGP_STOP (vcpu)
2917 - sigp stop; optional flags in parm
2918 KVM_S390_PROGRAM_INT (vcpu)
2919 - program check; code in parm
2920 KVM_S390_SIGP_SET_PREFIX (vcpu)
2921 - sigp set prefix; prefix address in parm
2922 KVM_S390_RESTART (vcpu)
2924 KVM_S390_INT_CLOCK_COMP (vcpu)
2925 - clock comparator interrupt
2926 KVM_S390_INT_CPU_TIMER (vcpu)
2927 - CPU timer interrupt
2928 KVM_S390_INT_VIRTIO (vm)
2929 - virtio external interrupt; external interrupt
2930 parameters in parm and parm64
2931 KVM_S390_INT_SERVICE (vm)
2932 - sclp external interrupt; sclp parameter in parm
2933 KVM_S390_INT_EMERGENCY (vcpu)
2934 - sigp emergency; source cpu in parm
2935 KVM_S390_INT_EXTERNAL_CALL (vcpu)
2936 - sigp external call; source cpu in parm
2937 KVM_S390_INT_IO(ai,cssid,ssid,schid) (vm)
2938 - compound value to indicate an
2939 I/O interrupt (ai - adapter interrupt; cssid,ssid,schid - subchannel);
2940 I/O interruption parameters in parm (subchannel) and parm64 (intparm,
2941 interruption subclass)
2942 KVM_S390_MCHK (vm, vcpu)
2943 - machine check interrupt; cr 14 bits in parm, machine check interrupt
2944 code in parm64 (note that machine checks needing further payload are not
2945 supported by this ioctl)
2947 This is an asynchronous vcpu ioctl and can be invoked from any thread.
2949 4.78 KVM_PPC_GET_HTAB_FD
2950 ------------------------
2952 :Capability: KVM_CAP_PPC_HTAB_FD
2953 :Architectures: powerpc
2955 :Parameters: Pointer to struct kvm_get_htab_fd (in)
2956 :Returns: file descriptor number (>= 0) on success, -1 on error
2958 This returns a file descriptor that can be used either to read out the
2959 entries in the guest's hashed page table (HPT), or to write entries to
2960 initialize the HPT. The returned fd can only be written to if the
2961 KVM_GET_HTAB_WRITE bit is set in the flags field of the argument, and
2962 can only be read if that bit is clear. The argument struct looks like
2965 /* For KVM_PPC_GET_HTAB_FD */
2966 struct kvm_get_htab_fd {
2972 /* Values for kvm_get_htab_fd.flags */
2973 #define KVM_GET_HTAB_BOLTED_ONLY ((__u64)0x1)
2974 #define KVM_GET_HTAB_WRITE ((__u64)0x2)
2976 The 'start_index' field gives the index in the HPT of the entry at
2977 which to start reading. It is ignored when writing.
2979 Reads on the fd will initially supply information about all
2980 "interesting" HPT entries. Interesting entries are those with the
2981 bolted bit set, if the KVM_GET_HTAB_BOLTED_ONLY bit is set, otherwise
2982 all entries. When the end of the HPT is reached, the read() will
2983 return. If read() is called again on the fd, it will start again from
2984 the beginning of the HPT, but will only return HPT entries that have
2985 changed since they were last read.
2987 Data read or written is structured as a header (8 bytes) followed by a
2988 series of valid HPT entries (16 bytes) each. The header indicates how
2989 many valid HPT entries there are and how many invalid entries follow
2990 the valid entries. The invalid entries are not represented explicitly
2991 in the stream. The header format is::
2993 struct kvm_get_htab_header {
2999 Writes to the fd create HPT entries starting at the index given in the
3000 header; first 'n_valid' valid entries with contents from the data
3001 written, then 'n_invalid' invalid entries, invalidating any previously
3002 valid entries found.
3004 4.79 KVM_CREATE_DEVICE
3005 ----------------------
3007 :Capability: KVM_CAP_DEVICE_CTRL
3009 :Parameters: struct kvm_create_device (in/out)
3010 :Returns: 0 on success, -1 on error
3014 ====== =======================================================
3015 ENODEV The device type is unknown or unsupported
3016 EEXIST Device already created, and this type of device may not
3017 be instantiated multiple times
3018 ====== =======================================================
3020 Other error conditions may be defined by individual device types or
3021 have their standard meanings.
3023 Creates an emulated device in the kernel. The file descriptor returned
3024 in fd can be used with KVM_SET/GET/HAS_DEVICE_ATTR.
3026 If the KVM_CREATE_DEVICE_TEST flag is set, only test whether the
3027 device type is supported (not necessarily whether it can be created
3030 Individual devices should not define flags. Attributes should be used
3031 for specifying any behavior that is not implied by the device type
3036 struct kvm_create_device {
3037 __u32 type; /* in: KVM_DEV_TYPE_xxx */
3038 __u32 fd; /* out: device handle */
3039 __u32 flags; /* in: KVM_CREATE_DEVICE_xxx */
3042 4.80 KVM_SET_DEVICE_ATTR/KVM_GET_DEVICE_ATTR
3043 --------------------------------------------
3045 :Capability: KVM_CAP_DEVICE_CTRL, KVM_CAP_VM_ATTRIBUTES for vm device,
3046 KVM_CAP_VCPU_ATTRIBUTES for vcpu device
3047 :Type: device ioctl, vm ioctl, vcpu ioctl
3048 :Parameters: struct kvm_device_attr
3049 :Returns: 0 on success, -1 on error
3053 ===== =============================================================
3054 ENXIO The group or attribute is unknown/unsupported for this device
3055 or hardware support is missing.
3056 EPERM The attribute cannot (currently) be accessed this way
3057 (e.g. read-only attribute, or attribute that only makes
3058 sense when the device is in a different state)
3059 ===== =============================================================
3061 Other error conditions may be defined by individual device types.
3063 Gets/sets a specified piece of device configuration and/or state. The
3064 semantics are device-specific. See individual device documentation in
3065 the "devices" directory. As with ONE_REG, the size of the data
3066 transferred is defined by the particular attribute.
3070 struct kvm_device_attr {
3071 __u32 flags; /* no flags currently defined */
3072 __u32 group; /* device-defined */
3073 __u64 attr; /* group-defined */
3074 __u64 addr; /* userspace address of attr data */
3077 4.81 KVM_HAS_DEVICE_ATTR
3078 ------------------------
3080 :Capability: KVM_CAP_DEVICE_CTRL, KVM_CAP_VM_ATTRIBUTES for vm device,
3081 KVM_CAP_VCPU_ATTRIBUTES for vcpu device
3082 :Type: device ioctl, vm ioctl, vcpu ioctl
3083 :Parameters: struct kvm_device_attr
3084 :Returns: 0 on success, -1 on error
3088 ===== =============================================================
3089 ENXIO The group or attribute is unknown/unsupported for this device
3090 or hardware support is missing.
3091 ===== =============================================================
3093 Tests whether a device supports a particular attribute. A successful
3094 return indicates the attribute is implemented. It does not necessarily
3095 indicate that the attribute can be read or written in the device's
3096 current state. "addr" is ignored.
3098 4.82 KVM_ARM_VCPU_INIT
3099 ----------------------
3102 :Architectures: arm, arm64
3104 :Parameters: struct kvm_vcpu_init (in)
3105 :Returns: 0 on success; -1 on error
3109 ====== =================================================================
3110 Â EINVAL Â Â Â the target is unknown, or the combination of features is invalid.
3111 Â ENOENT Â Â Â a features bit specified is unknown.
3112 ====== =================================================================
3114 This tells KVM what type of CPU to present to the guest, and what
3115 optional features it should have. Â This will cause a reset of the cpu
3116 registers to their initial values. Â If this is not called, KVM_RUN will
3117 return ENOEXEC for that vcpu.
3119 The initial values are defined as:
3121 * AArch64: EL1h, D, A, I and F bits set. All other bits
3123 * AArch32: SVC, A, I and F bits set. All other bits are
3125 - General Purpose registers, including PC and SP: set to 0
3126 - FPSIMD/NEON registers: set to 0
3127 - SVE registers: set to 0
3128 - System registers: Reset to their architecturally defined
3129 values as for a warm reset to EL1 (resp. SVC)
3131 Note that because some registers reflect machine topology, all vcpus
3132 should be created before this ioctl is invoked.
3134 Userspace can call this function multiple times for a given vcpu, including
3135 after the vcpu has been run. This will reset the vcpu to its initial
3136 state. All calls to this function after the initial call must use the same
3137 target and same set of feature flags, otherwise EINVAL will be returned.
3141 - KVM_ARM_VCPU_POWER_OFF: Starts the CPU in a power-off state.
3142 Depends on KVM_CAP_ARM_PSCI. If not set, the CPU will be powered on
3143 and execute guest code when KVM_RUN is called.
3144 - KVM_ARM_VCPU_EL1_32BIT: Starts the CPU in a 32bit mode.
3145 Depends on KVM_CAP_ARM_EL1_32BIT (arm64 only).
3146 - KVM_ARM_VCPU_PSCI_0_2: Emulate PSCI v0.2 (or a future revision
3147 backward compatible with v0.2) for the CPU.
3148 Depends on KVM_CAP_ARM_PSCI_0_2.
3149 - KVM_ARM_VCPU_PMU_V3: Emulate PMUv3 for the CPU.
3150 Depends on KVM_CAP_ARM_PMU_V3.
3152 - KVM_ARM_VCPU_PTRAUTH_ADDRESS: Enables Address Pointer authentication
3154 Depends on KVM_CAP_ARM_PTRAUTH_ADDRESS.
3155 If KVM_CAP_ARM_PTRAUTH_ADDRESS and KVM_CAP_ARM_PTRAUTH_GENERIC are
3156 both present, then both KVM_ARM_VCPU_PTRAUTH_ADDRESS and
3157 KVM_ARM_VCPU_PTRAUTH_GENERIC must be requested or neither must be
3160 - KVM_ARM_VCPU_PTRAUTH_GENERIC: Enables Generic Pointer authentication
3162 Depends on KVM_CAP_ARM_PTRAUTH_GENERIC.
3163 If KVM_CAP_ARM_PTRAUTH_ADDRESS and KVM_CAP_ARM_PTRAUTH_GENERIC are
3164 both present, then both KVM_ARM_VCPU_PTRAUTH_ADDRESS and
3165 KVM_ARM_VCPU_PTRAUTH_GENERIC must be requested or neither must be
3168 - KVM_ARM_VCPU_SVE: Enables SVE for the CPU (arm64 only).
3169 Depends on KVM_CAP_ARM_SVE.
3170 Requires KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE):
3172 * After KVM_ARM_VCPU_INIT:
3174 - KVM_REG_ARM64_SVE_VLS may be read using KVM_GET_ONE_REG: the
3175 initial value of this pseudo-register indicates the best set of
3176 vector lengths possible for a vcpu on this host.
3178 * Before KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE):
3180 - KVM_RUN and KVM_GET_REG_LIST are not available;
3182 - KVM_GET_ONE_REG and KVM_SET_ONE_REG cannot be used to access
3183 the scalable archietctural SVE registers
3184 KVM_REG_ARM64_SVE_ZREG(), KVM_REG_ARM64_SVE_PREG() or
3185 KVM_REG_ARM64_SVE_FFR;
3187 - KVM_REG_ARM64_SVE_VLS may optionally be written using
3188 KVM_SET_ONE_REG, to modify the set of vector lengths available
3191 * After KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE):
3193 - the KVM_REG_ARM64_SVE_VLS pseudo-register is immutable, and can
3194 no longer be written using KVM_SET_ONE_REG.
3196 4.83 KVM_ARM_PREFERRED_TARGET
3197 -----------------------------
3200 :Architectures: arm, arm64
3202 :Parameters: struct kvm_vcpu_init (out)
3203 :Returns: 0 on success; -1 on error
3207 ====== ==========================================
3208 ENODEV no preferred target available for the host
3209 ====== ==========================================
3211 This queries KVM for preferred CPU target type which can be emulated
3212 by KVM on underlying host.
3214 The ioctl returns struct kvm_vcpu_init instance containing information
3215 about preferred CPU target type and recommended features for it. The
3216 kvm_vcpu_init->features bitmap returned will have feature bits set if
3217 the preferred target recommends setting these features, but this is
3220 The information returned by this ioctl can be used to prepare an instance
3221 of struct kvm_vcpu_init for KVM_ARM_VCPU_INIT ioctl which will result in
3222 VCPU matching underlying host.
3225 4.84 KVM_GET_REG_LIST
3226 ---------------------
3229 :Architectures: arm, arm64, mips
3231 :Parameters: struct kvm_reg_list (in/out)
3232 :Returns: 0 on success; -1 on error
3236 ===== ==============================================================
3237 Â E2BIG Â Â Â Â the reg index list is too big to fit in the array specified by
3238 Â Â Â Â Â Â Â Â Â Â Â Â the user (the number required will be written into n).
3239 ===== ==============================================================
3243 struct kvm_reg_list {
3244 __u64 n; /* number of registers in reg[] */
3248 This ioctl returns the guest registers that are supported for the
3249 KVM_GET_ONE_REG/KVM_SET_ONE_REG calls.
3252 4.85 KVM_ARM_SET_DEVICE_ADDR (deprecated)
3253 -----------------------------------------
3255 :Capability: KVM_CAP_ARM_SET_DEVICE_ADDR
3256 :Architectures: arm, arm64
3258 :Parameters: struct kvm_arm_device_address (in)
3259 :Returns: 0 on success, -1 on error
3263 ====== ============================================
3264 ENODEV The device id is unknown
3265 ENXIO Device not supported on current system
3266 EEXIST Address already set
3267 E2BIG Address outside guest physical address space
3268 EBUSY Address overlaps with other device range
3269 ====== ============================================
3273 struct kvm_arm_device_addr {
3278 Specify a device address in the guest's physical address space where guests
3279 can access emulated or directly exposed devices, which the host kernel needs
3280 to know about. The id field is an architecture specific identifier for a
3283 ARM/arm64 divides the id field into two parts, a device id and an
3284 address type id specific to the individual device::
3286 Â bits: | 63 ... 32 | 31 ... 16 | 15 ... 0 |
3287 field: | 0x00000000 | device id | addr type id |
3289 ARM/arm64 currently only require this when using the in-kernel GIC
3290 support for the hardware VGIC features, using KVM_ARM_DEVICE_VGIC_V2
3291 as the device id. When setting the base address for the guest's
3292 mapping of the VGIC virtual CPU and distributor interface, the ioctl
3293 must be called after calling KVM_CREATE_IRQCHIP, but before calling
3294 KVM_RUN on any of the VCPUs. Calling this ioctl twice for any of the
3295 base addresses will return -EEXIST.
3297 Note, this IOCTL is deprecated and the more flexible SET/GET_DEVICE_ATTR API
3298 should be used instead.
3301 4.86 KVM_PPC_RTAS_DEFINE_TOKEN
3302 ------------------------------
3304 :Capability: KVM_CAP_PPC_RTAS
3307 :Parameters: struct kvm_rtas_token_args
3308 :Returns: 0 on success, -1 on error
3310 Defines a token value for a RTAS (Run Time Abstraction Services)
3311 service in order to allow it to be handled in the kernel. The
3312 argument struct gives the name of the service, which must be the name
3313 of a service that has a kernel-side implementation. If the token
3314 value is non-zero, it will be associated with that service, and
3315 subsequent RTAS calls by the guest specifying that token will be
3316 handled by the kernel. If the token value is 0, then any token
3317 associated with the service will be forgotten, and subsequent RTAS
3318 calls by the guest for that service will be passed to userspace to be
3321 4.87 KVM_SET_GUEST_DEBUG
3322 ------------------------
3324 :Capability: KVM_CAP_SET_GUEST_DEBUG
3325 :Architectures: x86, s390, ppc, arm64
3327 :Parameters: struct kvm_guest_debug (in)
3328 :Returns: 0 on success; -1 on error
3332 struct kvm_guest_debug {
3335 struct kvm_guest_debug_arch arch;
3338 Set up the processor specific debug registers and configure vcpu for
3339 handling guest debug events. There are two parts to the structure, the
3340 first a control bitfield indicates the type of debug events to handle
3341 when running. Common control bits are:
3343 - KVM_GUESTDBG_ENABLE: guest debugging is enabled
3344 - KVM_GUESTDBG_SINGLESTEP: the next run should single-step
3346 The top 16 bits of the control field are architecture specific control
3347 flags which can include the following:
3349 - KVM_GUESTDBG_USE_SW_BP: using software breakpoints [x86, arm64]
3350 - KVM_GUESTDBG_USE_HW_BP: using hardware breakpoints [x86, s390]
3351 - KVM_GUESTDBG_USE_HW: using hardware debug events [arm64]
3352 - KVM_GUESTDBG_INJECT_DB: inject DB type exception [x86]
3353 - KVM_GUESTDBG_INJECT_BP: inject BP type exception [x86]
3354 - KVM_GUESTDBG_EXIT_PENDING: trigger an immediate guest exit [s390]
3356 For example KVM_GUESTDBG_USE_SW_BP indicates that software breakpoints
3357 are enabled in memory so we need to ensure breakpoint exceptions are
3358 correctly trapped and the KVM run loop exits at the breakpoint and not
3359 running off into the normal guest vector. For KVM_GUESTDBG_USE_HW_BP
3360 we need to ensure the guest vCPUs architecture specific registers are
3361 updated to the correct (supplied) values.
3363 The second part of the structure is architecture specific and
3364 typically contains a set of debug registers.
3366 For arm64 the number of debug registers is implementation defined and
3367 can be determined by querying the KVM_CAP_GUEST_DEBUG_HW_BPS and
3368 KVM_CAP_GUEST_DEBUG_HW_WPS capabilities which return a positive number
3369 indicating the number of supported registers.
3371 For ppc, the KVM_CAP_PPC_GUEST_DEBUG_SSTEP capability indicates whether
3372 the single-step debug event (KVM_GUESTDBG_SINGLESTEP) is supported.
3374 Also when supported, KVM_CAP_SET_GUEST_DEBUG2 capability indicates the
3375 supported KVM_GUESTDBG_* bits in the control field.
3377 When debug events exit the main run loop with the reason
3378 KVM_EXIT_DEBUG with the kvm_debug_exit_arch part of the kvm_run
3379 structure containing architecture specific debug information.
3381 4.88 KVM_GET_EMULATED_CPUID
3382 ---------------------------
3384 :Capability: KVM_CAP_EXT_EMUL_CPUID
3387 :Parameters: struct kvm_cpuid2 (in/out)
3388 :Returns: 0 on success, -1 on error
3395 struct kvm_cpuid_entry2 entries[0];
3398 The member 'flags' is used for passing flags from userspace.
3402 #define KVM_CPUID_FLAG_SIGNIFCANT_INDEX BIT(0)
3403 #define KVM_CPUID_FLAG_STATEFUL_FUNC BIT(1) /* deprecated */
3404 #define KVM_CPUID_FLAG_STATE_READ_NEXT BIT(2) /* deprecated */
3406 struct kvm_cpuid_entry2 {
3417 This ioctl returns x86 cpuid features which are emulated by
3418 kvm.Userspace can use the information returned by this ioctl to query
3419 which features are emulated by kvm instead of being present natively.
3421 Userspace invokes KVM_GET_EMULATED_CPUID by passing a kvm_cpuid2
3422 structure with the 'nent' field indicating the number of entries in
3423 the variable-size array 'entries'. If the number of entries is too low
3424 to describe the cpu capabilities, an error (E2BIG) is returned. If the
3425 number is too high, the 'nent' field is adjusted and an error (ENOMEM)
3426 is returned. If the number is just right, the 'nent' field is adjusted
3427 to the number of valid entries in the 'entries' array, which is then
3430 The entries returned are the set CPUID bits of the respective features
3431 which kvm emulates, as returned by the CPUID instruction, with unknown
3432 or unsupported feature bits cleared.
3434 Features like x2apic, for example, may not be present in the host cpu
3435 but are exposed by kvm in KVM_GET_SUPPORTED_CPUID because they can be
3436 emulated efficiently and thus not included here.
3438 The fields in each entry are defined as follows:
3441 the eax value used to obtain the entry
3443 the ecx value used to obtain the entry (for entries that are
3446 an OR of zero or more of the following:
3448 KVM_CPUID_FLAG_SIGNIFCANT_INDEX:
3449 if the index field is valid
3453 the values returned by the cpuid instruction for
3454 this function/index combination
3456 4.89 KVM_S390_MEM_OP
3457 --------------------
3459 :Capability: KVM_CAP_S390_MEM_OP
3460 :Architectures: s390
3462 :Parameters: struct kvm_s390_mem_op (in)
3463 :Returns: = 0 on success,
3464 < 0 on generic error (e.g. -EFAULT or -ENOMEM),
3465 > 0 if an exception occurred while walking the page tables
3467 Read or write data from/to the logical (virtual) memory of a VCPU.
3469 Parameters are specified via the following structure::
3471 struct kvm_s390_mem_op {
3472 __u64 gaddr; /* the guest address */
3473 __u64 flags; /* flags */
3474 __u32 size; /* amount of bytes */
3475 __u32 op; /* type of operation */
3476 __u64 buf; /* buffer in userspace */
3477 __u8 ar; /* the access register number */
3478 __u8 reserved[31]; /* should be set to 0 */
3481 The type of operation is specified in the "op" field. It is either
3482 KVM_S390_MEMOP_LOGICAL_READ for reading from logical memory space or
3483 KVM_S390_MEMOP_LOGICAL_WRITE for writing to logical memory space. The
3484 KVM_S390_MEMOP_F_CHECK_ONLY flag can be set in the "flags" field to check
3485 whether the corresponding memory access would create an access exception
3486 (without touching the data in the memory at the destination). In case an
3487 access exception occurred while walking the MMU tables of the guest, the
3488 ioctl returns a positive error number to indicate the type of exception.
3489 This exception is also raised directly at the corresponding VCPU if the
3490 flag KVM_S390_MEMOP_F_INJECT_EXCEPTION is set in the "flags" field.
3492 The start address of the memory region has to be specified in the "gaddr"
3493 field, and the length of the region in the "size" field (which must not
3494 be 0). The maximum value for "size" can be obtained by checking the
3495 KVM_CAP_S390_MEM_OP capability. "buf" is the buffer supplied by the
3496 userspace application where the read data should be written to for
3497 KVM_S390_MEMOP_LOGICAL_READ, or where the data that should be written is
3498 stored for a KVM_S390_MEMOP_LOGICAL_WRITE. When KVM_S390_MEMOP_F_CHECK_ONLY
3499 is specified, "buf" is unused and can be NULL. "ar" designates the access
3500 register number to be used; the valid range is 0..15.
3502 The "reserved" field is meant for future extensions. It is not used by
3503 KVM with the currently defined set of flags.
3505 4.90 KVM_S390_GET_SKEYS
3506 -----------------------
3508 :Capability: KVM_CAP_S390_SKEYS
3509 :Architectures: s390
3511 :Parameters: struct kvm_s390_skeys
3512 :Returns: 0 on success, KVM_S390_GET_KEYS_NONE if guest is not using storage
3513 keys, negative value on error
3515 This ioctl is used to get guest storage key values on the s390
3516 architecture. The ioctl takes parameters via the kvm_s390_skeys struct::
3518 struct kvm_s390_skeys {
3521 __u64 skeydata_addr;
3526 The start_gfn field is the number of the first guest frame whose storage keys
3529 The count field is the number of consecutive frames (starting from start_gfn)
3530 whose storage keys to get. The count field must be at least 1 and the maximum
3531 allowed value is defined as KVM_S390_SKEYS_ALLOC_MAX. Values outside this range
3532 will cause the ioctl to return -EINVAL.
3534 The skeydata_addr field is the address to a buffer large enough to hold count
3535 bytes. This buffer will be filled with storage key data by the ioctl.
3537 4.91 KVM_S390_SET_SKEYS
3538 -----------------------
3540 :Capability: KVM_CAP_S390_SKEYS
3541 :Architectures: s390
3543 :Parameters: struct kvm_s390_skeys
3544 :Returns: 0 on success, negative value on error
3546 This ioctl is used to set guest storage key values on the s390
3547 architecture. The ioctl takes parameters via the kvm_s390_skeys struct.
3548 See section on KVM_S390_GET_SKEYS for struct definition.
3550 The start_gfn field is the number of the first guest frame whose storage keys
3553 The count field is the number of consecutive frames (starting from start_gfn)
3554 whose storage keys to get. The count field must be at least 1 and the maximum
3555 allowed value is defined as KVM_S390_SKEYS_ALLOC_MAX. Values outside this range
3556 will cause the ioctl to return -EINVAL.
3558 The skeydata_addr field is the address to a buffer containing count bytes of
3559 storage keys. Each byte in the buffer will be set as the storage key for a
3560 single frame starting at start_gfn for count frames.
3562 Note: If any architecturally invalid key value is found in the given data then
3563 the ioctl will return -EINVAL.
3568 :Capability: KVM_CAP_S390_INJECT_IRQ
3569 :Architectures: s390
3571 :Parameters: struct kvm_s390_irq (in)
3572 :Returns: 0 on success, -1 on error
3577 ====== =================================================================
3578 EINVAL interrupt type is invalid
3579 type is KVM_S390_SIGP_STOP and flag parameter is invalid value,
3580 type is KVM_S390_INT_EXTERNAL_CALL and code is bigger
3581 than the maximum of VCPUs
3582 EBUSY type is KVM_S390_SIGP_SET_PREFIX and vcpu is not stopped,
3583 type is KVM_S390_SIGP_STOP and a stop irq is already pending,
3584 type is KVM_S390_INT_EXTERNAL_CALL and an external call interrupt
3586 ====== =================================================================
3588 Allows to inject an interrupt to the guest.
3590 Using struct kvm_s390_irq as a parameter allows
3591 to inject additional payload which is not
3592 possible via KVM_S390_INTERRUPT.
3594 Interrupt parameters are passed via kvm_s390_irq::
3596 struct kvm_s390_irq {
3599 struct kvm_s390_io_info io;
3600 struct kvm_s390_ext_info ext;
3601 struct kvm_s390_pgm_info pgm;
3602 struct kvm_s390_emerg_info emerg;
3603 struct kvm_s390_extcall_info extcall;
3604 struct kvm_s390_prefix_info prefix;
3605 struct kvm_s390_stop_info stop;
3606 struct kvm_s390_mchk_info mchk;
3611 type can be one of the following:
3613 - KVM_S390_SIGP_STOP - sigp stop; parameter in .stop
3614 - KVM_S390_PROGRAM_INT - program check; parameters in .pgm
3615 - KVM_S390_SIGP_SET_PREFIX - sigp set prefix; parameters in .prefix
3616 - KVM_S390_RESTART - restart; no parameters
3617 - KVM_S390_INT_CLOCK_COMP - clock comparator interrupt; no parameters
3618 - KVM_S390_INT_CPU_TIMER - CPU timer interrupt; no parameters
3619 - KVM_S390_INT_EMERGENCY - sigp emergency; parameters in .emerg
3620 - KVM_S390_INT_EXTERNAL_CALL - sigp external call; parameters in .extcall
3621 - KVM_S390_MCHK - machine check interrupt; parameters in .mchk
3623 This is an asynchronous vcpu ioctl and can be invoked from any thread.
3625 4.94 KVM_S390_GET_IRQ_STATE
3626 ---------------------------
3628 :Capability: KVM_CAP_S390_IRQ_STATE
3629 :Architectures: s390
3631 :Parameters: struct kvm_s390_irq_state (out)
3632 :Returns: >= number of bytes copied into buffer,
3633 -EINVAL if buffer size is 0,
3634 -ENOBUFS if buffer size is too small to fit all pending interrupts,
3635 -EFAULT if the buffer address was invalid
3637 This ioctl allows userspace to retrieve the complete state of all currently
3638 pending interrupts in a single buffer. Use cases include migration
3639 and introspection. The parameter structure contains the address of a
3640 userspace buffer and its length::
3642 struct kvm_s390_irq_state {
3644 __u32 flags; /* will stay unused for compatibility reasons */
3646 __u32 reserved[4]; /* will stay unused for compatibility reasons */
3649 Userspace passes in the above struct and for each pending interrupt a
3650 struct kvm_s390_irq is copied to the provided buffer.
3652 The structure contains a flags and a reserved field for future extensions. As
3653 the kernel never checked for flags == 0 and QEMU never pre-zeroed flags and
3654 reserved, these fields can not be used in the future without breaking
3657 If -ENOBUFS is returned the buffer provided was too small and userspace
3658 may retry with a bigger buffer.
3660 4.95 KVM_S390_SET_IRQ_STATE
3661 ---------------------------
3663 :Capability: KVM_CAP_S390_IRQ_STATE
3664 :Architectures: s390
3666 :Parameters: struct kvm_s390_irq_state (in)
3667 :Returns: 0 on success,
3668 -EFAULT if the buffer address was invalid,
3669 -EINVAL for an invalid buffer length (see below),
3670 -EBUSY if there were already interrupts pending,
3671 errors occurring when actually injecting the
3672 interrupt. See KVM_S390_IRQ.
3674 This ioctl allows userspace to set the complete state of all cpu-local
3675 interrupts currently pending for the vcpu. It is intended for restoring
3676 interrupt state after a migration. The input parameter is a userspace buffer
3677 containing a struct kvm_s390_irq_state::
3679 struct kvm_s390_irq_state {
3681 __u32 flags; /* will stay unused for compatibility reasons */
3683 __u32 reserved[4]; /* will stay unused for compatibility reasons */
3686 The restrictions for flags and reserved apply as well.
3687 (see KVM_S390_GET_IRQ_STATE)
3689 The userspace memory referenced by buf contains a struct kvm_s390_irq
3690 for each interrupt to be injected into the guest.
3691 If one of the interrupts could not be injected for some reason the
3694 len must be a multiple of sizeof(struct kvm_s390_irq). It must be > 0
3695 and it must not exceed (max_vcpus + 32) * sizeof(struct kvm_s390_irq),
3696 which is the maximum number of possibly pending cpu-local interrupts.
3701 :Capability: KVM_CAP_X86_SMM
3705 :Returns: 0 on success, -1 on error
3707 Queues an SMI on the thread's vcpu.
3709 4.97 KVM_X86_SET_MSR_FILTER
3710 ----------------------------
3712 :Capability: KVM_X86_SET_MSR_FILTER
3715 :Parameters: struct kvm_msr_filter
3716 :Returns: 0 on success, < 0 on error
3720 struct kvm_msr_filter_range {
3721 #define KVM_MSR_FILTER_READ (1 << 0)
3722 #define KVM_MSR_FILTER_WRITE (1 << 1)
3724 __u32 nmsrs; /* number of msrs in bitmap */
3725 __u32 base; /* MSR index the bitmap starts at */
3726 __u8 *bitmap; /* a 1 bit allows the operations in flags, 0 denies */
3729 #define KVM_MSR_FILTER_MAX_RANGES 16
3730 struct kvm_msr_filter {
3731 #define KVM_MSR_FILTER_DEFAULT_ALLOW (0 << 0)
3732 #define KVM_MSR_FILTER_DEFAULT_DENY (1 << 0)
3734 struct kvm_msr_filter_range ranges[KVM_MSR_FILTER_MAX_RANGES];
3737 flags values for ``struct kvm_msr_filter_range``:
3739 ``KVM_MSR_FILTER_READ``
3741 Filter read accesses to MSRs using the given bitmap. A 0 in the bitmap
3742 indicates that a read should immediately fail, while a 1 indicates that
3743 a read for a particular MSR should be handled regardless of the default
3746 ``KVM_MSR_FILTER_WRITE``
3748 Filter write accesses to MSRs using the given bitmap. A 0 in the bitmap
3749 indicates that a write should immediately fail, while a 1 indicates that
3750 a write for a particular MSR should be handled regardless of the default
3753 ``KVM_MSR_FILTER_READ | KVM_MSR_FILTER_WRITE``
3755 Filter both read and write accesses to MSRs using the given bitmap. A 0
3756 in the bitmap indicates that both reads and writes should immediately fail,
3757 while a 1 indicates that reads and writes for a particular MSR are not
3758 filtered by this range.
3760 flags values for ``struct kvm_msr_filter``:
3762 ``KVM_MSR_FILTER_DEFAULT_ALLOW``
3764 If no filter range matches an MSR index that is getting accessed, KVM will
3765 fall back to allowing access to the MSR.
3767 ``KVM_MSR_FILTER_DEFAULT_DENY``
3769 If no filter range matches an MSR index that is getting accessed, KVM will
3770 fall back to rejecting access to the MSR. In this mode, all MSRs that should
3771 be processed by KVM need to explicitly be marked as allowed in the bitmaps.
3773 This ioctl allows user space to define up to 16 bitmaps of MSR ranges to
3774 specify whether a certain MSR access should be explicitly filtered for or not.
3776 If this ioctl has never been invoked, MSR accesses are not guarded and the
3777 default KVM in-kernel emulation behavior is fully preserved.
3779 Calling this ioctl with an empty set of ranges (all nmsrs == 0) disables MSR
3780 filtering. In that mode, ``KVM_MSR_FILTER_DEFAULT_DENY`` is invalid and causes
3783 As soon as the filtering is in place, every MSR access is processed through
3784 the filtering except for accesses to the x2APIC MSRs (from 0x800 to 0x8ff);
3785 x2APIC MSRs are always allowed, independent of the ``default_allow`` setting,
3786 and their behavior depends on the ``X2APIC_ENABLE`` bit of the APIC base
3789 If a bit is within one of the defined ranges, read and write accesses are
3790 guarded by the bitmap's value for the MSR index if the kind of access
3791 is included in the ``struct kvm_msr_filter_range`` flags. If no range
3792 cover this particular access, the behavior is determined by the flags
3793 field in the kvm_msr_filter struct: ``KVM_MSR_FILTER_DEFAULT_ALLOW``
3794 and ``KVM_MSR_FILTER_DEFAULT_DENY``.
3796 Each bitmap range specifies a range of MSRs to potentially allow access on.
3797 The range goes from MSR index [base .. base+nmsrs]. The flags field
3798 indicates whether reads, writes or both reads and writes are filtered
3799 by setting a 1 bit in the bitmap for the corresponding MSR index.
3801 If an MSR access is not permitted through the filtering, it generates a
3802 #GP inside the guest. When combined with KVM_CAP_X86_USER_SPACE_MSR, that
3803 allows user space to deflect and potentially handle various MSR accesses
3806 If a vCPU is in running state while this ioctl is invoked, the vCPU may
3807 experience inconsistent filtering behavior on MSR accesses.
3809 4.98 KVM_CREATE_SPAPR_TCE_64
3810 ----------------------------
3812 :Capability: KVM_CAP_SPAPR_TCE_64
3813 :Architectures: powerpc
3815 :Parameters: struct kvm_create_spapr_tce_64 (in)
3816 :Returns: file descriptor for manipulating the created TCE table
3818 This is an extension for KVM_CAP_SPAPR_TCE which only supports 32bit
3819 windows, described in 4.62 KVM_CREATE_SPAPR_TCE
3821 This capability uses extended struct in ioctl interface::
3823 /* for KVM_CAP_SPAPR_TCE_64 */
3824 struct kvm_create_spapr_tce_64 {
3828 __u64 offset; /* in pages */
3829 __u64 size; /* in pages */
3832 The aim of extension is to support an additional bigger DMA window with
3833 a variable page size.
3834 KVM_CREATE_SPAPR_TCE_64 receives a 64bit window size, an IOMMU page shift and
3835 a bus offset of the corresponding DMA window, @size and @offset are numbers
3838 @flags are not used at the moment.
3840 The rest of functionality is identical to KVM_CREATE_SPAPR_TCE.
3842 4.99 KVM_REINJECT_CONTROL
3843 -------------------------
3845 :Capability: KVM_CAP_REINJECT_CONTROL
3848 :Parameters: struct kvm_reinject_control (in)
3849 :Returns: 0 on success,
3850 -EFAULT if struct kvm_reinject_control cannot be read,
3851 -ENXIO if KVM_CREATE_PIT or KVM_CREATE_PIT2 didn't succeed earlier.
3853 i8254 (PIT) has two modes, reinject and !reinject. The default is reinject,
3854 where KVM queues elapsed i8254 ticks and monitors completion of interrupt from
3855 vector(s) that i8254 injects. Reinject mode dequeues a tick and injects its
3856 interrupt whenever there isn't a pending interrupt from i8254.
3857 !reinject mode injects an interrupt as soon as a tick arrives.
3861 struct kvm_reinject_control {
3866 pit_reinject = 0 (!reinject mode) is recommended, unless running an old
3867 operating system that uses the PIT for timing (e.g. Linux 2.4.x).
3869 4.100 KVM_PPC_CONFIGURE_V3_MMU
3870 ------------------------------
3872 :Capability: KVM_CAP_PPC_RADIX_MMU or KVM_CAP_PPC_HASH_MMU_V3
3875 :Parameters: struct kvm_ppc_mmuv3_cfg (in)
3876 :Returns: 0 on success,
3877 -EFAULT if struct kvm_ppc_mmuv3_cfg cannot be read,
3878 -EINVAL if the configuration is invalid
3880 This ioctl controls whether the guest will use radix or HPT (hashed
3881 page table) translation, and sets the pointer to the process table for
3886 struct kvm_ppc_mmuv3_cfg {
3888 __u64 process_table;
3891 There are two bits that can be set in flags; KVM_PPC_MMUV3_RADIX and
3892 KVM_PPC_MMUV3_GTSE. KVM_PPC_MMUV3_RADIX, if set, configures the guest
3893 to use radix tree translation, and if clear, to use HPT translation.
3894 KVM_PPC_MMUV3_GTSE, if set and if KVM permits it, configures the guest
3895 to be able to use the global TLB and SLB invalidation instructions;
3896 if clear, the guest may not use these instructions.
3898 The process_table field specifies the address and size of the guest
3899 process table, which is in the guest's space. This field is formatted
3900 as the second doubleword of the partition table entry, as defined in
3901 the Power ISA V3.00, Book III section 5.7.6.1.
3903 4.101 KVM_PPC_GET_RMMU_INFO
3904 ---------------------------
3906 :Capability: KVM_CAP_PPC_RADIX_MMU
3909 :Parameters: struct kvm_ppc_rmmu_info (out)
3910 :Returns: 0 on success,
3911 -EFAULT if struct kvm_ppc_rmmu_info cannot be written,
3912 -EINVAL if no useful information can be returned
3914 This ioctl returns a structure containing two things: (a) a list
3915 containing supported radix tree geometries, and (b) a list that maps
3916 page sizes to put in the "AP" (actual page size) field for the tlbie
3917 (TLB invalidate entry) instruction.
3921 struct kvm_ppc_rmmu_info {
3922 struct kvm_ppc_radix_geom {
3927 __u32 ap_encodings[8];
3930 The geometries[] field gives up to 8 supported geometries for the
3931 radix page table, in terms of the log base 2 of the smallest page
3932 size, and the number of bits indexed at each level of the tree, from
3933 the PTE level up to the PGD level in that order. Any unused entries
3934 will have 0 in the page_shift field.
3936 The ap_encodings gives the supported page sizes and their AP field
3937 encodings, encoded with the AP value in the top 3 bits and the log
3938 base 2 of the page size in the bottom 6 bits.
3940 4.102 KVM_PPC_RESIZE_HPT_PREPARE
3941 --------------------------------
3943 :Capability: KVM_CAP_SPAPR_RESIZE_HPT
3944 :Architectures: powerpc
3946 :Parameters: struct kvm_ppc_resize_hpt (in)
3947 :Returns: 0 on successful completion,
3948 >0 if a new HPT is being prepared, the value is an estimated
3949 number of milliseconds until preparation is complete,
3950 -EFAULT if struct kvm_reinject_control cannot be read,
3951 -EINVAL if the supplied shift or flags are invalid,
3952 -ENOMEM if unable to allocate the new HPT,
3954 Used to implement the PAPR extension for runtime resizing of a guest's
3955 Hashed Page Table (HPT). Specifically this starts, stops or monitors
3956 the preparation of a new potential HPT for the guest, essentially
3957 implementing the H_RESIZE_HPT_PREPARE hypercall.
3961 struct kvm_ppc_resize_hpt {
3967 If called with shift > 0 when there is no pending HPT for the guest,
3968 this begins preparation of a new pending HPT of size 2^(shift) bytes.
3969 It then returns a positive integer with the estimated number of
3970 milliseconds until preparation is complete.
3972 If called when there is a pending HPT whose size does not match that
3973 requested in the parameters, discards the existing pending HPT and
3974 creates a new one as above.
3976 If called when there is a pending HPT of the size requested, will:
3978 * If preparation of the pending HPT is already complete, return 0
3979 * If preparation of the pending HPT has failed, return an error
3980 code, then discard the pending HPT.
3981 * If preparation of the pending HPT is still in progress, return an
3982 estimated number of milliseconds until preparation is complete.
3984 If called with shift == 0, discards any currently pending HPT and
3985 returns 0 (i.e. cancels any in-progress preparation).
3987 flags is reserved for future expansion, currently setting any bits in
3988 flags will result in an -EINVAL.
3990 Normally this will be called repeatedly with the same parameters until
3991 it returns <= 0. The first call will initiate preparation, subsequent
3992 ones will monitor preparation until it completes or fails.
3994 4.103 KVM_PPC_RESIZE_HPT_COMMIT
3995 -------------------------------
3997 :Capability: KVM_CAP_SPAPR_RESIZE_HPT
3998 :Architectures: powerpc
4000 :Parameters: struct kvm_ppc_resize_hpt (in)
4001 :Returns: 0 on successful completion,
4002 -EFAULT if struct kvm_reinject_control cannot be read,
4003 -EINVAL if the supplied shift or flags are invalid,
4004 -ENXIO is there is no pending HPT, or the pending HPT doesn't
4005 have the requested size,
4006 -EBUSY if the pending HPT is not fully prepared,
4007 -ENOSPC if there was a hash collision when moving existing
4008 HPT entries to the new HPT,
4009 -EIO on other error conditions
4011 Used to implement the PAPR extension for runtime resizing of a guest's
4012 Hashed Page Table (HPT). Specifically this requests that the guest be
4013 transferred to working with the new HPT, essentially implementing the
4014 H_RESIZE_HPT_COMMIT hypercall.
4018 struct kvm_ppc_resize_hpt {
4024 This should only be called after KVM_PPC_RESIZE_HPT_PREPARE has
4025 returned 0 with the same parameters. In other cases
4026 KVM_PPC_RESIZE_HPT_COMMIT will return an error (usually -ENXIO or
4027 -EBUSY, though others may be possible if the preparation was started,
4030 This will have undefined effects on the guest if it has not already
4031 placed itself in a quiescent state where no vcpu will make MMU enabled
4034 On succsful completion, the pending HPT will become the guest's active
4035 HPT and the previous HPT will be discarded.
4037 On failure, the guest will still be operating on its previous HPT.
4039 4.104 KVM_X86_GET_MCE_CAP_SUPPORTED
4040 -----------------------------------
4042 :Capability: KVM_CAP_MCE
4045 :Parameters: u64 mce_cap (out)
4046 :Returns: 0 on success, -1 on error
4048 Returns supported MCE capabilities. The u64 mce_cap parameter
4049 has the same format as the MSR_IA32_MCG_CAP register. Supported
4050 capabilities will have the corresponding bits set.
4052 4.105 KVM_X86_SETUP_MCE
4053 -----------------------
4055 :Capability: KVM_CAP_MCE
4058 :Parameters: u64 mcg_cap (in)
4059 :Returns: 0 on success,
4060 -EFAULT if u64 mcg_cap cannot be read,
4061 -EINVAL if the requested number of banks is invalid,
4062 -EINVAL if requested MCE capability is not supported.
4064 Initializes MCE support for use. The u64 mcg_cap parameter
4065 has the same format as the MSR_IA32_MCG_CAP register and
4066 specifies which capabilities should be enabled. The maximum
4067 supported number of error-reporting banks can be retrieved when
4068 checking for KVM_CAP_MCE. The supported capabilities can be
4069 retrieved with KVM_X86_GET_MCE_CAP_SUPPORTED.
4071 4.106 KVM_X86_SET_MCE
4072 ---------------------
4074 :Capability: KVM_CAP_MCE
4077 :Parameters: struct kvm_x86_mce (in)
4078 :Returns: 0 on success,
4079 -EFAULT if struct kvm_x86_mce cannot be read,
4080 -EINVAL if the bank number is invalid,
4081 -EINVAL if VAL bit is not set in status field.
4083 Inject a machine check error (MCE) into the guest. The input
4086 struct kvm_x86_mce {
4096 If the MCE being reported is an uncorrected error, KVM will
4097 inject it as an MCE exception into the guest. If the guest
4098 MCG_STATUS register reports that an MCE is in progress, KVM
4099 causes an KVM_EXIT_SHUTDOWN vmexit.
4101 Otherwise, if the MCE is a corrected error, KVM will just
4102 store it in the corresponding bank (provided this bank is
4103 not holding a previously reported uncorrected error).
4105 4.107 KVM_S390_GET_CMMA_BITS
4106 ----------------------------
4108 :Capability: KVM_CAP_S390_CMMA_MIGRATION
4109 :Architectures: s390
4111 :Parameters: struct kvm_s390_cmma_log (in, out)
4112 :Returns: 0 on success, a negative value on error
4114 This ioctl is used to get the values of the CMMA bits on the s390
4115 architecture. It is meant to be used in two scenarios:
4117 - During live migration to save the CMMA values. Live migration needs
4118 to be enabled via the KVM_REQ_START_MIGRATION VM property.
4119 - To non-destructively peek at the CMMA values, with the flag
4120 KVM_S390_CMMA_PEEK set.
4122 The ioctl takes parameters via the kvm_s390_cmma_log struct. The desired
4123 values are written to a buffer whose location is indicated via the "values"
4124 member in the kvm_s390_cmma_log struct. The values in the input struct are
4125 also updated as needed.
4127 Each CMMA value takes up one byte.
4131 struct kvm_s390_cmma_log {
4142 start_gfn is the number of the first guest frame whose CMMA values are
4145 count is the length of the buffer in bytes,
4147 values points to the buffer where the result will be written to.
4149 If count is greater than KVM_S390_SKEYS_MAX, then it is considered to be
4150 KVM_S390_SKEYS_MAX. KVM_S390_SKEYS_MAX is re-used for consistency with
4153 The result is written in the buffer pointed to by the field values, and
4154 the values of the input parameter are updated as follows.
4156 Depending on the flags, different actions are performed. The only
4157 supported flag so far is KVM_S390_CMMA_PEEK.
4159 The default behaviour if KVM_S390_CMMA_PEEK is not set is:
4160 start_gfn will indicate the first page frame whose CMMA bits were dirty.
4161 It is not necessarily the same as the one passed as input, as clean pages
4164 count will indicate the number of bytes actually written in the buffer.
4165 It can (and very often will) be smaller than the input value, since the
4166 buffer is only filled until 16 bytes of clean values are found (which
4167 are then not copied in the buffer). Since a CMMA migration block needs
4168 the base address and the length, for a total of 16 bytes, we will send
4169 back some clean data if there is some dirty data afterwards, as long as
4170 the size of the clean data does not exceed the size of the header. This
4171 allows to minimize the amount of data to be saved or transferred over
4172 the network at the expense of more roundtrips to userspace. The next
4173 invocation of the ioctl will skip over all the clean values, saving
4174 potentially more than just the 16 bytes we found.
4176 If KVM_S390_CMMA_PEEK is set:
4177 the existing storage attributes are read even when not in migration
4178 mode, and no other action is performed;
4180 the output start_gfn will be equal to the input start_gfn,
4182 the output count will be equal to the input count, except if the end of
4183 memory has been reached.
4186 the field "remaining" will indicate the total number of dirty CMMA values
4187 still remaining, or 0 if KVM_S390_CMMA_PEEK is set and migration mode is
4192 values points to the userspace buffer where the result will be stored.
4194 This ioctl can fail with -ENOMEM if not enough memory can be allocated to
4195 complete the task, with -ENXIO if CMMA is not enabled, with -EINVAL if
4196 KVM_S390_CMMA_PEEK is not set but migration mode was not enabled, with
4197 -EFAULT if the userspace address is invalid or if no page table is
4198 present for the addresses (e.g. when using hugepages).
4200 4.108 KVM_S390_SET_CMMA_BITS
4201 ----------------------------
4203 :Capability: KVM_CAP_S390_CMMA_MIGRATION
4204 :Architectures: s390
4206 :Parameters: struct kvm_s390_cmma_log (in)
4207 :Returns: 0 on success, a negative value on error
4209 This ioctl is used to set the values of the CMMA bits on the s390
4210 architecture. It is meant to be used during live migration to restore
4211 the CMMA values, but there are no restrictions on its use.
4212 The ioctl takes parameters via the kvm_s390_cmma_values struct.
4213 Each CMMA value takes up one byte.
4217 struct kvm_s390_cmma_log {
4228 start_gfn indicates the starting guest frame number,
4230 count indicates how many values are to be considered in the buffer,
4232 flags is not used and must be 0.
4234 mask indicates which PGSTE bits are to be considered.
4236 remaining is not used.
4238 values points to the buffer in userspace where to store the values.
4240 This ioctl can fail with -ENOMEM if not enough memory can be allocated to
4241 complete the task, with -ENXIO if CMMA is not enabled, with -EINVAL if
4242 the count field is too large (e.g. more than KVM_S390_CMMA_SIZE_MAX) or
4243 if the flags field was not 0, with -EFAULT if the userspace address is
4244 invalid, if invalid pages are written to (e.g. after the end of memory)
4245 or if no page table is present for the addresses (e.g. when using
4248 4.109 KVM_PPC_GET_CPU_CHAR
4249 --------------------------
4251 :Capability: KVM_CAP_PPC_GET_CPU_CHAR
4252 :Architectures: powerpc
4254 :Parameters: struct kvm_ppc_cpu_char (out)
4255 :Returns: 0 on successful completion,
4256 -EFAULT if struct kvm_ppc_cpu_char cannot be written
4258 This ioctl gives userspace information about certain characteristics
4259 of the CPU relating to speculative execution of instructions and
4260 possible information leakage resulting from speculative execution (see
4261 CVE-2017-5715, CVE-2017-5753 and CVE-2017-5754). The information is
4262 returned in struct kvm_ppc_cpu_char, which looks like this::
4264 struct kvm_ppc_cpu_char {
4265 __u64 character; /* characteristics of the CPU */
4266 __u64 behaviour; /* recommended software behaviour */
4267 __u64 character_mask; /* valid bits in character */
4268 __u64 behaviour_mask; /* valid bits in behaviour */
4271 For extensibility, the character_mask and behaviour_mask fields
4272 indicate which bits of character and behaviour have been filled in by
4273 the kernel. If the set of defined bits is extended in future then
4274 userspace will be able to tell whether it is running on a kernel that
4275 knows about the new bits.
4277 The character field describes attributes of the CPU which can help
4278 with preventing inadvertent information disclosure - specifically,
4279 whether there is an instruction to flash-invalidate the L1 data cache
4280 (ori 30,30,0 or mtspr SPRN_TRIG2,rN), whether the L1 data cache is set
4281 to a mode where entries can only be used by the thread that created
4282 them, whether the bcctr[l] instruction prevents speculation, and
4283 whether a speculation barrier instruction (ori 31,31,0) is provided.
4285 The behaviour field describes actions that software should take to
4286 prevent inadvertent information disclosure, and thus describes which
4287 vulnerabilities the hardware is subject to; specifically whether the
4288 L1 data cache should be flushed when returning to user mode from the
4289 kernel, and whether a speculation barrier should be placed between an
4290 array bounds check and the array access.
4292 These fields use the same bit definitions as the new
4293 H_GET_CPU_CHARACTERISTICS hypercall.
4295 4.110 KVM_MEMORY_ENCRYPT_OP
4296 ---------------------------
4301 :Parameters: an opaque platform specific structure (in/out)
4302 :Returns: 0 on success; -1 on error
4304 If the platform supports creating encrypted VMs then this ioctl can be used
4305 for issuing platform-specific memory encryption commands to manage those
4308 Currently, this ioctl is used for issuing Secure Encrypted Virtualization
4309 (SEV) commands on AMD Processors. The SEV commands are defined in
4310 Documentation/virt/kvm/amd-memory-encryption.rst.
4312 4.111 KVM_MEMORY_ENCRYPT_REG_REGION
4313 -----------------------------------
4318 :Parameters: struct kvm_enc_region (in)
4319 :Returns: 0 on success; -1 on error
4321 This ioctl can be used to register a guest memory region which may
4322 contain encrypted data (e.g. guest RAM, SMRAM etc).
4324 It is used in the SEV-enabled guest. When encryption is enabled, a guest
4325 memory region may contain encrypted data. The SEV memory encryption
4326 engine uses a tweak such that two identical plaintext pages, each at
4327 different locations will have differing ciphertexts. So swapping or
4328 moving ciphertext of those pages will not result in plaintext being
4329 swapped. So relocating (or migrating) physical backing pages for the SEV
4330 guest will require some additional steps.
4332 Note: The current SEV key management spec does not provide commands to
4333 swap or migrate (move) ciphertext pages. Hence, for now we pin the guest
4334 memory region registered with the ioctl.
4336 4.112 KVM_MEMORY_ENCRYPT_UNREG_REGION
4337 -------------------------------------
4342 :Parameters: struct kvm_enc_region (in)
4343 :Returns: 0 on success; -1 on error
4345 This ioctl can be used to unregister the guest memory region registered
4346 with KVM_MEMORY_ENCRYPT_REG_REGION ioctl above.
4348 4.113 KVM_HYPERV_EVENTFD
4349 ------------------------
4351 :Capability: KVM_CAP_HYPERV_EVENTFD
4354 :Parameters: struct kvm_hyperv_eventfd (in)
4356 This ioctl (un)registers an eventfd to receive notifications from the guest on
4357 the specified Hyper-V connection id through the SIGNAL_EVENT hypercall, without
4358 causing a user exit. SIGNAL_EVENT hypercall with non-zero event flag number
4359 (bits 24-31) still triggers a KVM_EXIT_HYPERV_HCALL user exit.
4363 struct kvm_hyperv_eventfd {
4370 The conn_id field should fit within 24 bits::
4372 #define KVM_HYPERV_CONN_ID_MASK 0x00ffffff
4374 The acceptable values for the flags field are::
4376 #define KVM_HYPERV_EVENTFD_DEASSIGN (1 << 0)
4378 :Returns: 0 on success,
4379 -EINVAL if conn_id or flags is outside the allowed range,
4380 -ENOENT on deassign if the conn_id isn't registered,
4381 -EEXIST on assign if the conn_id is already registered
4383 4.114 KVM_GET_NESTED_STATE
4384 --------------------------
4386 :Capability: KVM_CAP_NESTED_STATE
4389 :Parameters: struct kvm_nested_state (in/out)
4390 :Returns: 0 on success, -1 on error
4394 ===== =============================================================
4395 E2BIG the total state size exceeds the value of 'size' specified by
4396 the user; the size required will be written into size.
4397 ===== =============================================================
4401 struct kvm_nested_state {
4407 struct kvm_vmx_nested_state_hdr vmx;
4408 struct kvm_svm_nested_state_hdr svm;
4410 /* Pad the header to 128 bytes. */
4415 struct kvm_vmx_nested_state_data vmx[0];
4416 struct kvm_svm_nested_state_data svm[0];
4420 #define KVM_STATE_NESTED_GUEST_MODE 0x00000001
4421 #define KVM_STATE_NESTED_RUN_PENDING 0x00000002
4422 #define KVM_STATE_NESTED_EVMCS 0x00000004
4424 #define KVM_STATE_NESTED_FORMAT_VMX 0
4425 #define KVM_STATE_NESTED_FORMAT_SVM 1
4427 #define KVM_STATE_NESTED_VMX_VMCS_SIZE 0x1000
4429 #define KVM_STATE_NESTED_VMX_SMM_GUEST_MODE 0x00000001
4430 #define KVM_STATE_NESTED_VMX_SMM_VMXON 0x00000002
4432 #define KVM_STATE_VMX_PREEMPTION_TIMER_DEADLINE 0x00000001
4434 struct kvm_vmx_nested_state_hdr {
4443 __u64 preemption_timer_deadline;
4446 struct kvm_vmx_nested_state_data {
4447 __u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
4448 __u8 shadow_vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
4451 This ioctl copies the vcpu's nested virtualization state from the kernel to
4454 The maximum size of the state can be retrieved by passing KVM_CAP_NESTED_STATE
4455 to the KVM_CHECK_EXTENSION ioctl().
4457 4.115 KVM_SET_NESTED_STATE
4458 --------------------------
4460 :Capability: KVM_CAP_NESTED_STATE
4463 :Parameters: struct kvm_nested_state (in)
4464 :Returns: 0 on success, -1 on error
4466 This copies the vcpu's kvm_nested_state struct from userspace to the kernel.
4467 For the definition of struct kvm_nested_state, see KVM_GET_NESTED_STATE.
4469 4.116 KVM_(UN)REGISTER_COALESCED_MMIO
4470 -------------------------------------
4472 :Capability: KVM_CAP_COALESCED_MMIO (for coalesced mmio)
4473 KVM_CAP_COALESCED_PIO (for coalesced pio)
4476 :Parameters: struct kvm_coalesced_mmio_zone
4477 :Returns: 0 on success, < 0 on error
4479 Coalesced I/O is a performance optimization that defers hardware
4480 register write emulation so that userspace exits are avoided. It is
4481 typically used to reduce the overhead of emulating frequently accessed
4484 When a hardware register is configured for coalesced I/O, write accesses
4485 do not exit to userspace and their value is recorded in a ring buffer
4486 that is shared between kernel and userspace.
4488 Coalesced I/O is used if one or more write accesses to a hardware
4489 register can be deferred until a read or a write to another hardware
4490 register on the same device. This last access will cause a vmexit and
4491 userspace will process accesses from the ring buffer before emulating
4492 it. That will avoid exiting to userspace on repeated writes.
4494 Coalesced pio is based on coalesced mmio. There is little difference
4495 between coalesced mmio and pio except that coalesced pio records accesses
4498 4.117 KVM_CLEAR_DIRTY_LOG (vm ioctl)
4499 ------------------------------------
4501 :Capability: KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
4502 :Architectures: x86, arm, arm64, mips
4504 :Parameters: struct kvm_clear_dirty_log (in)
4505 :Returns: 0 on success, -1 on error
4509 /* for KVM_CLEAR_DIRTY_LOG */
4510 struct kvm_clear_dirty_log {
4515 void __user *dirty_bitmap; /* one bit per page */
4520 The ioctl clears the dirty status of pages in a memory slot, according to
4521 the bitmap that is passed in struct kvm_clear_dirty_log's dirty_bitmap
4522 field. Bit 0 of the bitmap corresponds to page "first_page" in the
4523 memory slot, and num_pages is the size in bits of the input bitmap.
4524 first_page must be a multiple of 64; num_pages must also be a multiple of
4525 64 unless first_page + num_pages is the size of the memory slot. For each
4526 bit that is set in the input bitmap, the corresponding page is marked "clean"
4527 in KVM's dirty bitmap, and dirty tracking is re-enabled for that page
4528 (for example via write-protection, or by clearing the dirty bit in
4529 a page table entry).
4531 If KVM_CAP_MULTI_ADDRESS_SPACE is available, bits 16-31 of slot field specifies
4532 the address space for which you want to clear the dirty status. See
4533 KVM_SET_USER_MEMORY_REGION for details on the usage of slot field.
4535 This ioctl is mostly useful when KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
4536 is enabled; for more information, see the description of the capability.
4537 However, it can always be used as long as KVM_CHECK_EXTENSION confirms
4538 that KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is present.
4540 4.118 KVM_GET_SUPPORTED_HV_CPUID
4541 --------------------------------
4543 :Capability: KVM_CAP_HYPERV_CPUID (vcpu), KVM_CAP_SYS_HYPERV_CPUID (system)
4545 :Type: system ioctl, vcpu ioctl
4546 :Parameters: struct kvm_cpuid2 (in/out)
4547 :Returns: 0 on success, -1 on error
4554 struct kvm_cpuid_entry2 entries[0];
4557 struct kvm_cpuid_entry2 {
4568 This ioctl returns x86 cpuid features leaves related to Hyper-V emulation in
4569 KVM. Userspace can use the information returned by this ioctl to construct
4570 cpuid information presented to guests consuming Hyper-V enlightenments (e.g.
4571 Windows or Hyper-V guests).
4573 CPUID feature leaves returned by this ioctl are defined by Hyper-V Top Level
4574 Functional Specification (TLFS). These leaves can't be obtained with
4575 KVM_GET_SUPPORTED_CPUID ioctl because some of them intersect with KVM feature
4576 leaves (0x40000000, 0x40000001).
4578 Currently, the following list of CPUID leaves are returned:
4580 - HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS
4581 - HYPERV_CPUID_INTERFACE
4582 - HYPERV_CPUID_VERSION
4583 - HYPERV_CPUID_FEATURES
4584 - HYPERV_CPUID_ENLIGHTMENT_INFO
4585 - HYPERV_CPUID_IMPLEMENT_LIMITS
4586 - HYPERV_CPUID_NESTED_FEATURES
4587 - HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS
4588 - HYPERV_CPUID_SYNDBG_INTERFACE
4589 - HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES
4591 Userspace invokes KVM_GET_SUPPORTED_HV_CPUID by passing a kvm_cpuid2 structure
4592 with the 'nent' field indicating the number of entries in the variable-size
4593 array 'entries'. If the number of entries is too low to describe all Hyper-V
4594 feature leaves, an error (E2BIG) is returned. If the number is more or equal
4595 to the number of Hyper-V feature leaves, the 'nent' field is adjusted to the
4596 number of valid entries in the 'entries' array, which is then filled.
4598 'index' and 'flags' fields in 'struct kvm_cpuid_entry2' are currently reserved,
4599 userspace should not expect to get any particular value there.
4601 Note, vcpu version of KVM_GET_SUPPORTED_HV_CPUID is currently deprecated. Unlike
4602 system ioctl which exposes all supported feature bits unconditionally, vcpu
4603 version has the following quirks:
4605 - HYPERV_CPUID_NESTED_FEATURES leaf and HV_X64_ENLIGHTENED_VMCS_RECOMMENDED
4606 feature bit are only exposed when Enlightened VMCS was previously enabled
4607 on the corresponding vCPU (KVM_CAP_HYPERV_ENLIGHTENED_VMCS).
4608 - HV_STIMER_DIRECT_MODE_AVAILABLE bit is only exposed with in-kernel LAPIC.
4609 (presumes KVM_CREATE_IRQCHIP has already been called).
4611 4.119 KVM_ARM_VCPU_FINALIZE
4612 ---------------------------
4614 :Architectures: arm, arm64
4616 :Parameters: int feature (in)
4617 :Returns: 0 on success, -1 on error
4621 ====== ==============================================================
4622 EPERM feature not enabled, needs configuration, or already finalized
4623 EINVAL feature unknown or not present
4624 ====== ==============================================================
4626 Recognised values for feature:
4628 ===== ===========================================
4629 arm64 KVM_ARM_VCPU_SVE (requires KVM_CAP_ARM_SVE)
4630 ===== ===========================================
4632 Finalizes the configuration of the specified vcpu feature.
4634 The vcpu must already have been initialised, enabling the affected feature, by
4635 means of a successful KVM_ARM_VCPU_INIT call with the appropriate flag set in
4638 For affected vcpu features, this is a mandatory step that must be performed
4639 before the vcpu is fully usable.
4641 Between KVM_ARM_VCPU_INIT and KVM_ARM_VCPU_FINALIZE, the feature may be
4642 configured by use of ioctls such as KVM_SET_ONE_REG. The exact configuration
4643 that should be performaned and how to do it are feature-dependent.
4645 Other calls that depend on a particular feature being finalized, such as
4646 KVM_RUN, KVM_GET_REG_LIST, KVM_GET_ONE_REG and KVM_SET_ONE_REG, will fail with
4647 -EPERM unless the feature has already been finalized by means of a
4648 KVM_ARM_VCPU_FINALIZE call.
4650 See KVM_ARM_VCPU_INIT for details of vcpu features that require finalization
4653 4.120 KVM_SET_PMU_EVENT_FILTER
4654 ------------------------------
4656 :Capability: KVM_CAP_PMU_EVENT_FILTER
4659 :Parameters: struct kvm_pmu_event_filter (in)
4660 :Returns: 0 on success, -1 on error
4664 struct kvm_pmu_event_filter {
4667 __u32 fixed_counter_bitmap;
4673 This ioctl restricts the set of PMU events that the guest can program.
4674 The argument holds a list of events which will be allowed or denied.
4675 The eventsel+umask of each event the guest attempts to program is compared
4676 against the events field to determine whether the guest should have access.
4677 The events field only controls general purpose counters; fixed purpose
4678 counters are controlled by the fixed_counter_bitmap.
4680 No flags are defined yet, the field must be zero.
4682 Valid values for 'action'::
4684 #define KVM_PMU_EVENT_ALLOW 0
4685 #define KVM_PMU_EVENT_DENY 1
4687 4.121 KVM_PPC_SVM_OFF
4688 ---------------------
4691 :Architectures: powerpc
4694 :Returns: 0 on successful completion,
4698 ====== ================================================================
4699 EINVAL if ultravisor failed to terminate the secure guest
4700 ENOMEM if hypervisor failed to allocate new radix page tables for guest
4701 ====== ================================================================
4703 This ioctl is used to turn off the secure mode of the guest or transition
4704 the guest from secure mode to normal mode. This is invoked when the guest
4705 is reset. This has no effect if called for a normal guest.
4707 This ioctl issues an ultravisor call to terminate the secure guest,
4708 unpins the VPA pages and releases all the device pages that are used to
4709 track the secure pages by hypervisor.
4711 4.122 KVM_S390_NORMAL_RESET
4712 ---------------------------
4714 :Capability: KVM_CAP_S390_VCPU_RESETS
4715 :Architectures: s390
4720 This ioctl resets VCPU registers and control structures according to
4721 the cpu reset definition in the POP (Principles Of Operation).
4723 4.123 KVM_S390_INITIAL_RESET
4724 ----------------------------
4727 :Architectures: s390
4732 This ioctl resets VCPU registers and control structures according to
4733 the initial cpu reset definition in the POP. However, the cpu is not
4734 put into ESA mode. This reset is a superset of the normal reset.
4736 4.124 KVM_S390_CLEAR_RESET
4737 --------------------------
4739 :Capability: KVM_CAP_S390_VCPU_RESETS
4740 :Architectures: s390
4745 This ioctl resets VCPU registers and control structures according to
4746 the clear cpu reset definition in the POP. However, the cpu is not put
4747 into ESA mode. This reset is a superset of the initial reset.
4750 4.125 KVM_S390_PV_COMMAND
4751 -------------------------
4753 :Capability: KVM_CAP_S390_PROTECTED
4754 :Architectures: s390
4756 :Parameters: struct kvm_pv_cmd
4757 :Returns: 0 on success, < 0 on error
4762 __u32 cmd; /* Command to be executed */
4763 __u16 rc; /* Ultravisor return code */
4764 __u16 rrc; /* Ultravisor return reason code */
4765 __u64 data; /* Data or address */
4766 __u32 flags; /* flags for future extensions. Must be 0 for now */
4773 Allocate memory and register the VM with the Ultravisor, thereby
4774 donating memory to the Ultravisor that will become inaccessible to
4775 KVM. All existing CPUs are converted to protected ones. After this
4776 command has succeeded, any CPU added via hotplug will become
4777 protected during its creation as well.
4781 ===== =============================
4782 EINTR an unmasked signal is pending
4783 ===== =============================
4787 Deregister the VM from the Ultravisor and reclaim the memory that
4788 had been donated to the Ultravisor, making it usable by the kernel
4789 again. All registered VCPUs are converted back to non-protected
4792 KVM_PV_VM_SET_SEC_PARMS
4793 Pass the image header from VM memory to the Ultravisor in
4794 preparation of image unpacking and verification.
4797 Unpack (protect and decrypt) a page of the encrypted boot image.
4800 Verify the integrity of the unpacked image. Only if this succeeds,
4801 KVM is allowed to start protected VCPUs.
4803 4.126 KVM_X86_SET_MSR_FILTER
4804 ----------------------------
4806 :Capability: KVM_X86_SET_MSR_FILTER
4809 :Parameters: struct kvm_msr_filter
4810 :Returns: 0 on success, < 0 on error
4814 struct kvm_msr_filter_range {
4815 #define KVM_MSR_FILTER_READ (1 << 0)
4816 #define KVM_MSR_FILTER_WRITE (1 << 1)
4818 __u32 nmsrs; /* number of msrs in bitmap */
4819 __u32 base; /* MSR index the bitmap starts at */
4820 __u8 *bitmap; /* a 1 bit allows the operations in flags, 0 denies */
4823 #define KVM_MSR_FILTER_MAX_RANGES 16
4824 struct kvm_msr_filter {
4825 #define KVM_MSR_FILTER_DEFAULT_ALLOW (0 << 0)
4826 #define KVM_MSR_FILTER_DEFAULT_DENY (1 << 0)
4828 struct kvm_msr_filter_range ranges[KVM_MSR_FILTER_MAX_RANGES];
4831 flags values for ``struct kvm_msr_filter_range``:
4833 ``KVM_MSR_FILTER_READ``
4835 Filter read accesses to MSRs using the given bitmap. A 0 in the bitmap
4836 indicates that a read should immediately fail, while a 1 indicates that
4837 a read for a particular MSR should be handled regardless of the default
4840 ``KVM_MSR_FILTER_WRITE``
4842 Filter write accesses to MSRs using the given bitmap. A 0 in the bitmap
4843 indicates that a write should immediately fail, while a 1 indicates that
4844 a write for a particular MSR should be handled regardless of the default
4847 ``KVM_MSR_FILTER_READ | KVM_MSR_FILTER_WRITE``
4849 Filter both read and write accesses to MSRs using the given bitmap. A 0
4850 in the bitmap indicates that both reads and writes should immediately fail,
4851 while a 1 indicates that reads and writes for a particular MSR are not
4852 filtered by this range.
4854 flags values for ``struct kvm_msr_filter``:
4856 ``KVM_MSR_FILTER_DEFAULT_ALLOW``
4858 If no filter range matches an MSR index that is getting accessed, KVM will
4859 fall back to allowing access to the MSR.
4861 ``KVM_MSR_FILTER_DEFAULT_DENY``
4863 If no filter range matches an MSR index that is getting accessed, KVM will
4864 fall back to rejecting access to the MSR. In this mode, all MSRs that should
4865 be processed by KVM need to explicitly be marked as allowed in the bitmaps.
4867 This ioctl allows user space to define up to 16 bitmaps of MSR ranges to
4868 specify whether a certain MSR access should be explicitly filtered for or not.
4870 If this ioctl has never been invoked, MSR accesses are not guarded and the
4871 default KVM in-kernel emulation behavior is fully preserved.
4873 Calling this ioctl with an empty set of ranges (all nmsrs == 0) disables MSR
4874 filtering. In that mode, ``KVM_MSR_FILTER_DEFAULT_DENY`` is invalid and causes
4877 As soon as the filtering is in place, every MSR access is processed through
4878 the filtering except for accesses to the x2APIC MSRs (from 0x800 to 0x8ff);
4879 x2APIC MSRs are always allowed, independent of the ``default_allow`` setting,
4880 and their behavior depends on the ``X2APIC_ENABLE`` bit of the APIC base
4883 If a bit is within one of the defined ranges, read and write accesses are
4884 guarded by the bitmap's value for the MSR index if the kind of access
4885 is included in the ``struct kvm_msr_filter_range`` flags. If no range
4886 cover this particular access, the behavior is determined by the flags
4887 field in the kvm_msr_filter struct: ``KVM_MSR_FILTER_DEFAULT_ALLOW``
4888 and ``KVM_MSR_FILTER_DEFAULT_DENY``.
4890 Each bitmap range specifies a range of MSRs to potentially allow access on.
4891 The range goes from MSR index [base .. base+nmsrs]. The flags field
4892 indicates whether reads, writes or both reads and writes are filtered
4893 by setting a 1 bit in the bitmap for the corresponding MSR index.
4895 If an MSR access is not permitted through the filtering, it generates a
4896 #GP inside the guest. When combined with KVM_CAP_X86_USER_SPACE_MSR, that
4897 allows user space to deflect and potentially handle various MSR accesses
4900 Note, invoking this ioctl with a vCPU is running is inherently racy. However,
4901 KVM does guarantee that vCPUs will see either the previous filter or the new
4902 filter, e.g. MSRs with identical settings in both the old and new filter will
4903 have deterministic behavior.
4905 4.127 KVM_XEN_HVM_SET_ATTR
4906 --------------------------
4908 :Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO
4911 :Parameters: struct kvm_xen_hvm_attr
4912 :Returns: 0 on success, < 0 on error
4916 struct kvm_xen_hvm_attr {
4931 KVM_XEN_ATTR_TYPE_LONG_MODE
4932 Sets the ABI mode of the VM to 32-bit or 64-bit (long mode). This
4933 determines the layout of the shared info pages exposed to the VM.
4935 KVM_XEN_ATTR_TYPE_SHARED_INFO
4936 Sets the guest physical frame number at which the Xen "shared info"
4937 page resides. Note that although Xen places vcpu_info for the first
4938 32 vCPUs in the shared_info page, KVM does not automatically do so
4939 and instead requires that KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO be used
4940 explicitly even when the vcpu_info for a given vCPU resides at the
4941 "default" location in the shared_info page. This is because KVM is
4942 not aware of the Xen CPU id which is used as the index into the
4943 vcpu_info[] array, so cannot know the correct default location.
4945 KVM_XEN_ATTR_TYPE_UPCALL_VECTOR
4946 Sets the exception vector used to deliver Xen event channel upcalls.
4948 4.127 KVM_XEN_HVM_GET_ATTR
4949 --------------------------
4951 :Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO
4954 :Parameters: struct kvm_xen_hvm_attr
4955 :Returns: 0 on success, < 0 on error
4957 Allows Xen VM attributes to be read. For the structure and types,
4958 see KVM_XEN_HVM_SET_ATTR above.
4960 4.128 KVM_XEN_VCPU_SET_ATTR
4961 ---------------------------
4963 :Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO
4966 :Parameters: struct kvm_xen_vcpu_attr
4967 :Returns: 0 on success, < 0 on error
4971 struct kvm_xen_vcpu_attr {
4979 __u64 state_entry_time;
4981 __u64 time_runnable;
4990 KVM_XEN_VCPU_ATTR_TYPE_VCPU_INFO
4991 Sets the guest physical address of the vcpu_info for a given vCPU.
4993 KVM_XEN_VCPU_ATTR_TYPE_VCPU_TIME_INFO
4994 Sets the guest physical address of an additional pvclock structure
4995 for a given vCPU. This is typically used for guest vsyscall support.
4997 KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR
4998 Sets the guest physical address of the vcpu_runstate_info for a given
4999 vCPU. This is how a Xen guest tracks CPU state such as steal time.
5001 KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT
5002 Sets the runstate (RUNSTATE_running/_runnable/_blocked/_offline) of
5003 the given vCPU from the .u.runstate.state member of the structure.
5004 KVM automatically accounts running and runnable time but blocked
5005 and offline states are only entered explicitly.
5007 KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_DATA
5008 Sets all fields of the vCPU runstate data from the .u.runstate member
5009 of the structure, including the current runstate. The state_entry_time
5010 must equal the sum of the other four times.
5012 KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST
5013 This *adds* the contents of the .u.runstate members of the structure
5014 to the corresponding members of the given vCPU's runstate data, thus
5015 permitting atomic adjustments to the runstate times. The adjustment
5016 to the state_entry_time must equal the sum of the adjustments to the
5017 other four times. The state field must be set to -1, or to a valid
5018 runstate value (RUNSTATE_running, RUNSTATE_runnable, RUNSTATE_blocked
5019 or RUNSTATE_offline) to set the current accounted state as of the
5020 adjusted state_entry_time.
5022 4.129 KVM_XEN_VCPU_GET_ATTR
5023 ---------------------------
5025 :Capability: KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_SHARED_INFO
5028 :Parameters: struct kvm_xen_vcpu_attr
5029 :Returns: 0 on success, < 0 on error
5031 Allows Xen vCPU attributes to be read. For the structure and types,
5032 see KVM_XEN_VCPU_SET_ATTR above.
5034 The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used
5035 with the KVM_XEN_VCPU_GET_ATTR ioctl.
5037 5. The kvm_run structure
5038 ========================
5040 Application code obtains a pointer to the kvm_run structure by
5041 mmap()ing a vcpu fd. From that point, application code can control
5042 execution by changing fields in kvm_run prior to calling the KVM_RUN
5043 ioctl, and obtain information about the reason KVM_RUN returned by
5044 looking up structure members.
5050 __u8 request_interrupt_window;
5052 Request that KVM_RUN return when it becomes possible to inject external
5053 interrupts into the guest. Useful in conjunction with KVM_INTERRUPT.
5057 __u8 immediate_exit;
5059 This field is polled once when KVM_RUN starts; if non-zero, KVM_RUN
5060 exits immediately, returning -EINTR. In the common scenario where a
5061 signal is used to "kick" a VCPU out of KVM_RUN, this field can be used
5062 to avoid usage of KVM_SET_SIGNAL_MASK, which has worse scalability.
5063 Rather than blocking the signal outside KVM_RUN, userspace can set up
5064 a signal handler that sets run->immediate_exit to a non-zero value.
5066 This field is ignored if KVM_CAP_IMMEDIATE_EXIT is not available.
5075 When KVM_RUN has returned successfully (return value 0), this informs
5076 application code why KVM_RUN has returned. Allowable values for this
5077 field are detailed below.
5081 __u8 ready_for_interrupt_injection;
5083 If request_interrupt_window has been specified, this field indicates
5084 an interrupt can be injected now with KVM_INTERRUPT.
5090 The value of the current interrupt flag. Only valid if in-kernel
5091 local APIC is not used.
5097 More architecture-specific flags detailing state of the VCPU that may
5098 affect the device's behavior. Current defined flags::
5100 /* x86, set if the VCPU is in system management mode */
5101 #define KVM_RUN_X86_SMM (1 << 0)
5102 /* x86, set if bus lock detected in VM */
5103 #define KVM_RUN_BUS_LOCK (1 << 1)
5107 /* in (pre_kvm_run), out (post_kvm_run) */
5110 The value of the cr8 register. Only valid if in-kernel local APIC is
5111 not used. Both input and output.
5117 The value of the APIC BASE msr. Only valid if in-kernel local
5118 APIC is not used. Both input and output.
5123 /* KVM_EXIT_UNKNOWN */
5125 __u64 hardware_exit_reason;
5128 If exit_reason is KVM_EXIT_UNKNOWN, the vcpu has exited due to unknown
5129 reasons. Further architecture-specific information is available in
5130 hardware_exit_reason.
5134 /* KVM_EXIT_FAIL_ENTRY */
5136 __u64 hardware_entry_failure_reason;
5137 __u32 cpu; /* if KVM_LAST_CPU */
5140 If exit_reason is KVM_EXIT_FAIL_ENTRY, the vcpu could not be run due
5141 to unknown reasons. Further architecture-specific information is
5142 available in hardware_entry_failure_reason.
5146 /* KVM_EXIT_EXCEPTION */
5158 #define KVM_EXIT_IO_IN 0
5159 #define KVM_EXIT_IO_OUT 1
5161 __u8 size; /* bytes */
5164 __u64 data_offset; /* relative to kvm_run start */
5167 If exit_reason is KVM_EXIT_IO, then the vcpu has
5168 executed a port I/O instruction which could not be satisfied by kvm.
5169 data_offset describes where the data is located (KVM_EXIT_IO_OUT) or
5170 where kvm expects application code to place the data for the next
5171 KVM_RUN invocation (KVM_EXIT_IO_IN). Data format is a packed array.
5175 /* KVM_EXIT_DEBUG */
5177 struct kvm_debug_exit_arch arch;
5180 If the exit_reason is KVM_EXIT_DEBUG, then a vcpu is processing a debug event
5181 for which architecture specific information is returned.
5193 If exit_reason is KVM_EXIT_MMIO, then the vcpu has
5194 executed a memory-mapped I/O instruction which could not be satisfied
5195 by kvm. The 'data' member contains the written data if 'is_write' is
5196 true, and should be filled by application code otherwise.
5198 The 'data' member contains, in its first 'len' bytes, the value as it would
5199 appear if the VCPU performed a load or store of the appropriate width directly
5204 For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_PAPR, KVM_EXIT_XEN,
5205 KVM_EXIT_EPR, KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR the corresponding
5206 operations are complete (and guest state is consistent) only after userspace
5207 has re-entered the kernel with KVM_RUN. The kernel side will first finish
5208 incomplete operations and then check for pending signals.
5210 The pending state of the operation is not preserved in state which is
5211 visible to userspace, thus userspace should ensure that the operation is
5212 completed before performing a live migration. Userspace can re-enter the
5213 guest with an unmasked signal pending or with the immediate_exit field set
5214 to complete pending operations without allowing any further instructions
5219 /* KVM_EXIT_HYPERCALL */
5228 Unused. This was once used for 'hypercall to userspace'. To implement
5229 such functionality, use KVM_EXIT_IO (x86) or KVM_EXIT_MMIO (all except s390).
5231 .. note:: KVM_EXIT_IO is significantly faster than KVM_EXIT_MMIO.
5235 /* KVM_EXIT_TPR_ACCESS */
5242 To be documented (KVM_TPR_ACCESS_REPORTING).
5246 /* KVM_EXIT_S390_SIEIC */
5249 __u64 mask; /* psw upper half */
5250 __u64 addr; /* psw lower half */
5259 /* KVM_EXIT_S390_RESET */
5260 #define KVM_S390_RESET_POR 1
5261 #define KVM_S390_RESET_CLEAR 2
5262 #define KVM_S390_RESET_SUBSYSTEM 4
5263 #define KVM_S390_RESET_CPU_INIT 8
5264 #define KVM_S390_RESET_IPL 16
5265 __u64 s390_reset_flags;
5271 /* KVM_EXIT_S390_UCONTROL */
5273 __u64 trans_exc_code;
5277 s390 specific. A page fault has occurred for a user controlled virtual
5278 machine (KVM_VM_S390_UNCONTROL) on it's host page table that cannot be
5279 resolved by the kernel.
5280 The program code and the translation exception code that were placed
5281 in the cpu's lowcore are presented here as defined by the z Architecture
5282 Principles of Operation Book in the Chapter for Dynamic Address Translation
5294 Deprecated - was used for 440 KVM.
5303 MOL uses a special hypercall interface it calls 'OSI'. To enable it, we catch
5304 hypercalls and exit with this exit struct that contains all the guest gprs.
5306 If exit_reason is KVM_EXIT_OSI, then the vcpu has triggered such a hypercall.
5307 Userspace can now handle the hypercall and when it's done modify the gprs as
5308 necessary. Upon guest entry all guest GPRs will then be replaced by the values
5313 /* KVM_EXIT_PAPR_HCALL */
5320 This is used on 64-bit PowerPC when emulating a pSeries partition,
5321 e.g. with the 'pseries' machine type in qemu. It occurs when the
5322 guest does a hypercall using the 'sc 1' instruction. The 'nr' field
5323 contains the hypercall number (from the guest R3), and 'args' contains
5324 the arguments (from the guest R4 - R12). Userspace should put the
5325 return code in 'ret' and any extra returned values in args[].
5326 The possible hypercalls are defined in the Power Architecture Platform
5327 Requirements (PAPR) document available from www.power.org (free
5328 developer registration required to access it).
5332 /* KVM_EXIT_S390_TSCH */
5334 __u16 subchannel_id;
5335 __u16 subchannel_nr;
5342 s390 specific. This exit occurs when KVM_CAP_S390_CSS_SUPPORT has been enabled
5343 and TEST SUBCHANNEL was intercepted. If dequeued is set, a pending I/O
5344 interrupt for the target subchannel has been dequeued and subchannel_id,
5345 subchannel_nr, io_int_parm and io_int_word contain the parameters for that
5346 interrupt. ipb is needed for instruction parameter decoding.
5355 On FSL BookE PowerPC chips, the interrupt controller has a fast patch
5356 interrupt acknowledge path to the core. When the core successfully
5357 delivers an interrupt, it automatically populates the EPR register with
5358 the interrupt vector number and acknowledges the interrupt inside
5359 the interrupt controller.
5361 In case the interrupt controller lives in user space, we need to do
5362 the interrupt acknowledge cycle through it to fetch the next to be
5363 delivered interrupt vector using this exit.
5365 It gets triggered whenever both KVM_CAP_PPC_EPR are enabled and an
5366 external interrupt has just been delivered into the guest. User space
5367 should put the acknowledged interrupt vector into the 'epr' field.
5371 /* KVM_EXIT_SYSTEM_EVENT */
5373 #define KVM_SYSTEM_EVENT_SHUTDOWN 1
5374 #define KVM_SYSTEM_EVENT_RESET 2
5375 #define KVM_SYSTEM_EVENT_CRASH 3
5380 If exit_reason is KVM_EXIT_SYSTEM_EVENT then the vcpu has triggered
5381 a system-level event using some architecture specific mechanism (hypercall
5382 or some special instruction). In case of ARM/ARM64, this is triggered using
5383 HVC instruction based PSCI call from the vcpu. The 'type' field describes
5384 the system-level event type. The 'flags' field describes architecture
5385 specific flags for the system-level event.
5387 Valid values for 'type' are:
5389 - KVM_SYSTEM_EVENT_SHUTDOWN -- the guest has requested a shutdown of the
5390 VM. Userspace is not obliged to honour this, and if it does honour
5391 this does not need to destroy the VM synchronously (ie it may call
5392 KVM_RUN again before shutdown finally occurs).
5393 - KVM_SYSTEM_EVENT_RESET -- the guest has requested a reset of the VM.
5394 As with SHUTDOWN, userspace can choose to ignore the request, or
5395 to schedule the reset to occur in the future and may call KVM_RUN again.
5396 - KVM_SYSTEM_EVENT_CRASH -- the guest crash occurred and the guest
5397 has requested a crash condition maintenance. Userspace can choose
5398 to ignore the request, or to gather VM memory core dump and/or
5399 reset/shutdown of the VM.
5403 /* KVM_EXIT_IOAPIC_EOI */
5408 Indicates that the VCPU's in-kernel local APIC received an EOI for a
5409 level-triggered IOAPIC interrupt. This exit only triggers when the
5410 IOAPIC is implemented in userspace (i.e. KVM_CAP_SPLIT_IRQCHIP is enabled);
5411 the userspace IOAPIC should process the EOI and retrigger the interrupt if
5412 it is still asserted. Vector is the LAPIC interrupt vector for which the
5417 struct kvm_hyperv_exit {
5418 #define KVM_EXIT_HYPERV_SYNIC 1
5419 #define KVM_EXIT_HYPERV_HCALL 2
5420 #define KVM_EXIT_HYPERV_SYNDBG 3
5447 /* KVM_EXIT_HYPERV */
5448 struct kvm_hyperv_exit hyperv;
5450 Indicates that the VCPU exits into userspace to process some tasks
5451 related to Hyper-V emulation.
5453 Valid values for 'type' are:
5455 - KVM_EXIT_HYPERV_SYNIC -- synchronously notify user-space about
5457 Hyper-V SynIC state change. Notification is used to remap SynIC
5458 event/message pages and to enable/disable SynIC messages/events processing
5461 - KVM_EXIT_HYPERV_SYNDBG -- synchronously notify user-space about
5463 Hyper-V Synthetic debugger state change. Notification is used to either update
5464 the pending_page location or to send a control command (send the buffer located
5465 in send_page or recv a buffer to recv_page).
5469 /* KVM_EXIT_ARM_NISV */
5475 Used on arm and arm64 systems. If a guest accesses memory not in a memslot,
5476 KVM will typically return to userspace and ask it to do MMIO emulation on its
5477 behalf. However, for certain classes of instructions, no instruction decode
5478 (direction, length of memory access) is provided, and fetching and decoding
5479 the instruction from the VM is overly complicated to live in the kernel.
5481 Historically, when this situation occurred, KVM would print a warning and kill
5482 the VM. KVM assumed that if the guest accessed non-memslot memory, it was
5483 trying to do I/O, which just couldn't be emulated, and the warning message was
5484 phrased accordingly. However, what happened more often was that a guest bug
5485 caused access outside the guest memory areas which should lead to a more
5486 meaningful warning message and an external abort in the guest, if the access
5487 did not fall within an I/O window.
5489 Userspace implementations can query for KVM_CAP_ARM_NISV_TO_USER, and enable
5490 this capability at VM creation. Once this is done, these types of errors will
5491 instead return to userspace with KVM_EXIT_ARM_NISV, with the valid bits from
5492 the HSR (arm) and ESR_EL2 (arm64) in the esr_iss field, and the faulting IPA
5493 in the fault_ipa field. Userspace can either fix up the access if it's
5494 actually an I/O access by decoding the instruction from guest memory (if it's
5495 very brave) and continue executing the guest, or it can decide to suspend,
5496 dump, or restart the guest.
5498 Note that KVM does not skip the faulting instruction as it does for
5499 KVM_EXIT_MMIO, but userspace has to emulate any change to the processing state
5500 if it decides to decode and emulate the instruction.
5504 /* KVM_EXIT_X86_RDMSR / KVM_EXIT_X86_WRMSR */
5506 __u8 error; /* user -> kernel */
5508 __u32 reason; /* kernel -> user */
5509 __u32 index; /* kernel -> user */
5510 __u64 data; /* kernel <-> user */
5513 Used on x86 systems. When the VM capability KVM_CAP_X86_USER_SPACE_MSR is
5514 enabled, MSR accesses to registers that would invoke a #GP by KVM kernel code
5515 will instead trigger a KVM_EXIT_X86_RDMSR exit for reads and KVM_EXIT_X86_WRMSR
5518 The "reason" field specifies why the MSR trap occurred. User space will only
5519 receive MSR exit traps when a particular reason was requested during through
5520 ENABLE_CAP. Currently valid exit reasons are:
5522 KVM_MSR_EXIT_REASON_UNKNOWN - access to MSR that is unknown to KVM
5523 KVM_MSR_EXIT_REASON_INVAL - access to invalid MSRs or reserved bits
5524 KVM_MSR_EXIT_REASON_FILTER - access blocked by KVM_X86_SET_MSR_FILTER
5526 For KVM_EXIT_X86_RDMSR, the "index" field tells user space which MSR the guest
5527 wants to read. To respond to this request with a successful read, user space
5528 writes the respective data into the "data" field and must continue guest
5529 execution to ensure the read data is transferred into guest register state.
5531 If the RDMSR request was unsuccessful, user space indicates that with a "1" in
5532 the "error" field. This will inject a #GP into the guest when the VCPU is
5535 For KVM_EXIT_X86_WRMSR, the "index" field tells user space which MSR the guest
5536 wants to write. Once finished processing the event, user space must continue
5537 vCPU execution. If the MSR write was unsuccessful, user space also sets the
5538 "error" field to "1".
5543 struct kvm_xen_exit {
5544 #define KVM_EXIT_XEN_HCALL 1
5557 struct kvm_hyperv_exit xen;
5559 Indicates that the VCPU exits into userspace to process some tasks
5560 related to Xen emulation.
5562 Valid values for 'type' are:
5564 - KVM_EXIT_XEN_HCALL -- synchronously notify user-space about Xen hypercall.
5565 Userspace is expected to place the hypercall result into the appropriate
5566 field before invoking KVM_RUN again.
5570 /* Fix the size of the union. */
5575 * shared registers between kvm and userspace.
5576 * kvm_valid_regs specifies the register classes set by the host
5577 * kvm_dirty_regs specified the register classes dirtied by userspace
5578 * struct kvm_sync_regs is architecture specific, as well as the
5579 * bits for kvm_valid_regs and kvm_dirty_regs
5581 __u64 kvm_valid_regs;
5582 __u64 kvm_dirty_regs;
5584 struct kvm_sync_regs regs;
5585 char padding[SYNC_REGS_SIZE_BYTES];
5588 If KVM_CAP_SYNC_REGS is defined, these fields allow userspace to access
5589 certain guest registers without having to call SET/GET_*REGS. Thus we can
5590 avoid some system call overhead if userspace has to handle the exit.
5591 Userspace can query the validity of the structure by checking
5592 kvm_valid_regs for specific bits. These bits are architecture specific
5593 and usually define the validity of a groups of registers. (e.g. one bit
5594 for general purpose registers)
5596 Please note that the kernel is allowed to use the kvm_run structure as the
5597 primary storage for certain register types. Therefore, the kernel may use the
5598 values in kvm_run even if the corresponding bit in kvm_dirty_regs is not set.
5606 6. Capabilities that can be enabled on vCPUs
5607 ============================================
5609 There are certain capabilities that change the behavior of the virtual CPU or
5610 the virtual machine when enabled. To enable them, please see section 4.37.
5611 Below you can find a list of capabilities and what their effect on the vCPU or
5612 the virtual machine is when enabling them.
5614 The following information is provided along with the description:
5617 which instruction set architectures provide this ioctl.
5618 x86 includes both i386 and x86_64.
5621 whether this is a per-vcpu or per-vm capability.
5624 what parameters are accepted by the capability.
5627 the return value. General error numbers (EBADF, ENOMEM, EINVAL)
5628 are not detailed, but errors with specific meanings are.
5637 :Returns: 0 on success; -1 on error
5639 This capability enables interception of OSI hypercalls that otherwise would
5640 be treated as normal system calls to be injected into the guest. OSI hypercalls
5641 were invented by Mac-on-Linux to have a standardized communication mechanism
5642 between the guest and the host.
5644 When this capability is enabled, KVM_EXIT_OSI can occur.
5647 6.2 KVM_CAP_PPC_PAPR
5648 --------------------
5653 :Returns: 0 on success; -1 on error
5655 This capability enables interception of PAPR hypercalls. PAPR hypercalls are
5656 done using the hypercall instruction "sc 1".
5658 It also sets the guest privilege level to "supervisor" mode. Usually the guest
5659 runs in "hypervisor" privilege mode with a few missing features.
5661 In addition to the above, it changes the semantics of SDR1. In this mode, the
5662 HTAB address part of SDR1 contains an HVA instead of a GPA, as PAPR keeps the
5663 HTAB invisible to the guest.
5665 When this capability is enabled, KVM_EXIT_PAPR_HCALL can occur.
5673 :Parameters: args[0] is the address of a struct kvm_config_tlb
5674 :Returns: 0 on success; -1 on error
5678 struct kvm_config_tlb {
5685 Configures the virtual CPU's TLB array, establishing a shared memory area
5686 between userspace and KVM. The "params" and "array" fields are userspace
5687 addresses of mmu-type-specific data structures. The "array_len" field is an
5688 safety mechanism, and should be set to the size in bytes of the memory that
5689 userspace has reserved for the array. It must be at least the size dictated
5690 by "mmu_type" and "params".
5692 While KVM_RUN is active, the shared region is under control of KVM. Its
5693 contents are undefined, and any modification by userspace results in
5694 boundedly undefined behavior.
5696 On return from KVM_RUN, the shared region will reflect the current state of
5697 the guest's TLB. If userspace makes any changes, it must call KVM_DIRTY_TLB
5698 to tell KVM which entries have been changed, prior to calling KVM_RUN again
5701 For mmu types KVM_MMU_FSL_BOOKE_NOHV and KVM_MMU_FSL_BOOKE_HV:
5703 - The "params" field is of type "struct kvm_book3e_206_tlb_params".
5704 - The "array" field points to an array of type "struct
5705 kvm_book3e_206_tlb_entry".
5706 - The array consists of all entries in the first TLB, followed by all
5707 entries in the second TLB.
5708 - Within a TLB, entries are ordered first by increasing set number. Within a
5709 set, entries are ordered by way (increasing ESEL).
5710 - The hash for determining set number in TLB0 is: (MAS2 >> 12) & (num_sets - 1)
5711 where "num_sets" is the tlb_sizes[] value divided by the tlb_ways[] value.
5712 - The tsize field of mas1 shall be set to 4K on TLB0, even though the
5713 hardware ignores this value for TLB0.
5715 6.4 KVM_CAP_S390_CSS_SUPPORT
5716 ----------------------------
5718 :Architectures: s390
5721 :Returns: 0 on success; -1 on error
5723 This capability enables support for handling of channel I/O instructions.
5725 TEST PENDING INTERRUPTION and the interrupt portion of TEST SUBCHANNEL are
5726 handled in-kernel, while the other I/O instructions are passed to userspace.
5728 When this capability is enabled, KVM_EXIT_S390_TSCH will occur on TEST
5729 SUBCHANNEL intercepts.
5731 Note that even though this capability is enabled per-vcpu, the complete
5732 virtual machine is affected.
5739 :Parameters: args[0] defines whether the proxy facility is active
5740 :Returns: 0 on success; -1 on error
5742 This capability enables or disables the delivery of interrupts through the
5743 external proxy facility.
5745 When enabled (args[0] != 0), every time the guest gets an external interrupt
5746 delivered, it automatically exits into user space with a KVM_EXIT_EPR exit
5747 to receive the topmost interrupt vector.
5749 When disabled (args[0] == 0), behavior is as if this facility is unsupported.
5751 When this capability is enabled, KVM_EXIT_EPR can occur.
5753 6.6 KVM_CAP_IRQ_MPIC
5754 --------------------
5757 :Parameters: args[0] is the MPIC device fd;
5758 args[1] is the MPIC CPU number for this vcpu
5760 This capability connects the vcpu to an in-kernel MPIC device.
5762 6.7 KVM_CAP_IRQ_XICS
5763 --------------------
5767 :Parameters: args[0] is the XICS device fd;
5768 args[1] is the XICS CPU number (server ID) for this vcpu
5770 This capability connects the vcpu to an in-kernel XICS device.
5772 6.8 KVM_CAP_S390_IRQCHIP
5773 ------------------------
5775 :Architectures: s390
5779 This capability enables the in-kernel irqchip for s390. Please refer to
5780 "4.24 KVM_CREATE_IRQCHIP" for details.
5782 6.9 KVM_CAP_MIPS_FPU
5783 --------------------
5785 :Architectures: mips
5787 :Parameters: args[0] is reserved for future use (should be 0).
5789 This capability allows the use of the host Floating Point Unit by the guest. It
5790 allows the Config1.FP bit to be set to enable the FPU in the guest. Once this is
5791 done the ``KVM_REG_MIPS_FPR_*`` and ``KVM_REG_MIPS_FCR_*`` registers can be
5792 accessed (depending on the current guest FPU register mode), and the Status.FR,
5793 Config5.FRE bits are accessible via the KVM API and also from the guest,
5794 depending on them being supported by the FPU.
5796 6.10 KVM_CAP_MIPS_MSA
5797 ---------------------
5799 :Architectures: mips
5801 :Parameters: args[0] is reserved for future use (should be 0).
5803 This capability allows the use of the MIPS SIMD Architecture (MSA) by the guest.
5804 It allows the Config3.MSAP bit to be set to enable the use of MSA by the guest.
5805 Once this is done the ``KVM_REG_MIPS_VEC_*`` and ``KVM_REG_MIPS_MSA_*``
5806 registers can be accessed, and the Config5.MSAEn bit is accessible via the
5807 KVM API and also from the guest.
5809 6.74 KVM_CAP_SYNC_REGS
5810 ----------------------
5812 :Architectures: s390, x86
5813 :Target: s390: always enabled, x86: vcpu
5815 :Returns: x86: KVM_CHECK_EXTENSION returns a bit-array indicating which register
5817 (bitfields defined in arch/x86/include/uapi/asm/kvm.h).
5819 As described above in the kvm_sync_regs struct info in section 5 (kvm_run):
5820 KVM_CAP_SYNC_REGS "allow[s] userspace to access certain guest registers
5821 without having to call SET/GET_*REGS". This reduces overhead by eliminating
5822 repeated ioctl calls for setting and/or getting register values. This is
5823 particularly important when userspace is making synchronous guest state
5824 modifications, e.g. when emulating and/or intercepting instructions in
5827 For s390 specifics, please refer to the source code.
5831 - the register sets to be copied out to kvm_run are selectable
5832 by userspace (rather that all sets being copied out for every exit).
5833 - vcpu_events are available in addition to regs and sregs.
5835 For x86, the 'kvm_valid_regs' field of struct kvm_run is overloaded to
5836 function as an input bit-array field set by userspace to indicate the
5837 specific register sets to be copied out on the next exit.
5839 To indicate when userspace has modified values that should be copied into
5840 the vCPU, the all architecture bitarray field, 'kvm_dirty_regs' must be set.
5841 This is done using the same bitflags as for the 'kvm_valid_regs' field.
5842 If the dirty bit is not set, then the register set values will not be copied
5843 into the vCPU even if they've been modified.
5845 Unused bitfields in the bitarrays must be set to zero.
5849 struct kvm_sync_regs {
5850 struct kvm_regs regs;
5851 struct kvm_sregs sregs;
5852 struct kvm_vcpu_events events;
5855 6.75 KVM_CAP_PPC_IRQ_XIVE
5856 -------------------------
5860 :Parameters: args[0] is the XIVE device fd;
5861 args[1] is the XIVE CPU number (server ID) for this vcpu
5863 This capability connects the vcpu to an in-kernel XIVE device.
5865 7. Capabilities that can be enabled on VMs
5866 ==========================================
5868 There are certain capabilities that change the behavior of the virtual
5869 machine when enabled. To enable them, please see section 4.37. Below
5870 you can find a list of capabilities and what their effect on the VM
5871 is when enabling them.
5873 The following information is provided along with the description:
5876 which instruction set architectures provide this ioctl.
5877 x86 includes both i386 and x86_64.
5880 what parameters are accepted by the capability.
5883 the return value. General error numbers (EBADF, ENOMEM, EINVAL)
5884 are not detailed, but errors with specific meanings are.
5887 7.1 KVM_CAP_PPC_ENABLE_HCALL
5888 ----------------------------
5891 :Parameters: args[0] is the sPAPR hcall number;
5892 args[1] is 0 to disable, 1 to enable in-kernel handling
5894 This capability controls whether individual sPAPR hypercalls (hcalls)
5895 get handled by the kernel or not. Enabling or disabling in-kernel
5896 handling of an hcall is effective across the VM. On creation, an
5897 initial set of hcalls are enabled for in-kernel handling, which
5898 consists of those hcalls for which in-kernel handlers were implemented
5899 before this capability was implemented. If disabled, the kernel will
5900 not to attempt to handle the hcall, but will always exit to userspace
5901 to handle it. Note that it may not make sense to enable some and
5902 disable others of a group of related hcalls, but KVM does not prevent
5903 userspace from doing that.
5905 If the hcall number specified is not one that has an in-kernel
5906 implementation, the KVM_ENABLE_CAP ioctl will fail with an EINVAL
5909 7.2 KVM_CAP_S390_USER_SIGP
5910 --------------------------
5912 :Architectures: s390
5915 This capability controls which SIGP orders will be handled completely in user
5916 space. With this capability enabled, all fast orders will be handled completely
5923 - CONDITIONAL EMERGENCY SIGNAL
5925 All other orders will be handled completely in user space.
5927 Only privileged operation exceptions will be checked for in the kernel (or even
5928 in the hardware prior to interception). If this capability is not enabled, the
5929 old way of handling SIGP orders is used (partially in kernel and user space).
5931 7.3 KVM_CAP_S390_VECTOR_REGISTERS
5932 ---------------------------------
5934 :Architectures: s390
5936 :Returns: 0 on success, negative value on error
5938 Allows use of the vector registers introduced with z13 processor, and
5939 provides for the synchronization between host and user space. Will
5940 return -EINVAL if the machine does not support vectors.
5942 7.4 KVM_CAP_S390_USER_STSI
5943 --------------------------
5945 :Architectures: s390
5948 This capability allows post-handlers for the STSI instruction. After
5949 initial handling in the kernel, KVM exits to user space with
5950 KVM_EXIT_S390_STSI to allow user space to insert further data.
5952 Before exiting to userspace, kvm handlers should fill in s390_stsi field of
5964 @addr - guest address of STSI SYSIB
5968 @ar - access register number
5970 KVM handlers should exit to userspace with rc = -EREMOTE.
5972 7.5 KVM_CAP_SPLIT_IRQCHIP
5973 -------------------------
5976 :Parameters: args[0] - number of routes reserved for userspace IOAPICs
5977 :Returns: 0 on success, -1 on error
5979 Create a local apic for each processor in the kernel. This can be used
5980 instead of KVM_CREATE_IRQCHIP if the userspace VMM wishes to emulate the
5981 IOAPIC and PIC (and also the PIT, even though this has to be enabled
5984 This capability also enables in kernel routing of interrupt requests;
5985 when KVM_CAP_SPLIT_IRQCHIP only routes of KVM_IRQ_ROUTING_MSI type are
5986 used in the IRQ routing table. The first args[0] MSI routes are reserved
5987 for the IOAPIC pins. Whenever the LAPIC receives an EOI for these routes,
5988 a KVM_EXIT_IOAPIC_EOI vmexit will be reported to userspace.
5990 Fails if VCPU has already been created, or if the irqchip is already in the
5991 kernel (i.e. KVM_CREATE_IRQCHIP has already been called).
5996 :Architectures: s390
5999 Allows use of runtime-instrumentation introduced with zEC12 processor.
6000 Will return -EINVAL if the machine does not support runtime-instrumentation.
6001 Will return -EBUSY if a VCPU has already been created.
6003 7.7 KVM_CAP_X2APIC_API
6004 ----------------------
6007 :Parameters: args[0] - features that should be enabled
6008 :Returns: 0 on success, -EINVAL when args[0] contains invalid features
6010 Valid feature flags in args[0] are::
6012 #define KVM_X2APIC_API_USE_32BIT_IDS (1ULL << 0)
6013 #define KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK (1ULL << 1)
6015 Enabling KVM_X2APIC_API_USE_32BIT_IDS changes the behavior of
6016 KVM_SET_GSI_ROUTING, KVM_SIGNAL_MSI, KVM_SET_LAPIC, and KVM_GET_LAPIC,
6017 allowing the use of 32-bit APIC IDs. See KVM_CAP_X2APIC_API in their
6018 respective sections.
6020 KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK must be enabled for x2APIC to work
6021 in logical mode or with more than 255 VCPUs. Otherwise, KVM treats 0xff
6022 as a broadcast even in x2APIC mode in order to support physical x2APIC
6023 without interrupt remapping. This is undesirable in logical mode,
6024 where 0xff represents CPUs 0-7 in cluster 0.
6026 7.8 KVM_CAP_S390_USER_INSTR0
6027 ----------------------------
6029 :Architectures: s390
6032 With this capability enabled, all illegal instructions 0x0000 (2 bytes) will
6033 be intercepted and forwarded to user space. User space can use this
6034 mechanism e.g. to realize 2-byte software breakpoints. The kernel will
6035 not inject an operating exception for these instructions, user space has
6036 to take care of that.
6038 This capability can be enabled dynamically even if VCPUs were already
6039 created and are running.
6044 :Architectures: s390
6046 :Returns: 0 on success; -EINVAL if the machine does not support
6047 guarded storage; -EBUSY if a VCPU has already been created.
6049 Allows use of guarded storage for the KVM guest.
6051 7.10 KVM_CAP_S390_AIS
6052 ---------------------
6054 :Architectures: s390
6057 Allow use of adapter-interruption suppression.
6058 :Returns: 0 on success; -EBUSY if a VCPU has already been created.
6060 7.11 KVM_CAP_PPC_SMT
6061 --------------------
6064 :Parameters: vsmt_mode, flags
6066 Enabling this capability on a VM provides userspace with a way to set
6067 the desired virtual SMT mode (i.e. the number of virtual CPUs per
6068 virtual core). The virtual SMT mode, vsmt_mode, must be a power of 2
6069 between 1 and 8. On POWER8, vsmt_mode must also be no greater than
6070 the number of threads per subcore for the host. Currently flags must
6071 be 0. A successful call to enable this capability will result in
6072 vsmt_mode being returned when the KVM_CAP_PPC_SMT capability is
6073 subsequently queried for the VM. This capability is only supported by
6074 HV KVM, and can only be set before any VCPUs have been created.
6075 The KVM_CAP_PPC_SMT_POSSIBLE capability indicates which virtual SMT
6076 modes are available.
6078 7.12 KVM_CAP_PPC_FWNMI
6079 ----------------------
6084 With this capability a machine check exception in the guest address
6085 space will cause KVM to exit the guest with NMI exit reason. This
6086 enables QEMU to build error log and branch to guest kernel registered
6087 machine check handling routine. Without this capability KVM will
6088 branch to guests' 0x200 interrupt vector.
6090 7.13 KVM_CAP_X86_DISABLE_EXITS
6091 ------------------------------
6094 :Parameters: args[0] defines which exits are disabled
6095 :Returns: 0 on success, -EINVAL when args[0] contains invalid exits
6097 Valid bits in args[0] are::
6099 #define KVM_X86_DISABLE_EXITS_MWAIT (1 << 0)
6100 #define KVM_X86_DISABLE_EXITS_HLT (1 << 1)
6101 #define KVM_X86_DISABLE_EXITS_PAUSE (1 << 2)
6102 #define KVM_X86_DISABLE_EXITS_CSTATE (1 << 3)
6104 Enabling this capability on a VM provides userspace with a way to no
6105 longer intercept some instructions for improved latency in some
6106 workloads, and is suggested when vCPUs are associated to dedicated
6107 physical CPUs. More bits can be added in the future; userspace can
6108 just pass the KVM_CHECK_EXTENSION result to KVM_ENABLE_CAP to disable
6111 Do not enable KVM_FEATURE_PV_UNHALT if you disable HLT exits.
6113 7.14 KVM_CAP_S390_HPAGE_1M
6114 --------------------------
6116 :Architectures: s390
6118 :Returns: 0 on success, -EINVAL if hpage module parameter was not set
6119 or cmma is enabled, or the VM has the KVM_VM_S390_UCONTROL
6122 With this capability the KVM support for memory backing with 1m pages
6123 through hugetlbfs can be enabled for a VM. After the capability is
6124 enabled, cmma can't be enabled anymore and pfmfi and the storage key
6125 interpretation are disabled. If cmma has already been enabled or the
6126 hpage module parameter is not set to 1, -EINVAL is returned.
6128 While it is generally possible to create a huge page backed VM without
6129 this capability, the VM will not be able to run.
6131 7.15 KVM_CAP_MSR_PLATFORM_INFO
6132 ------------------------------
6135 :Parameters: args[0] whether feature should be enabled or not
6137 With this capability, a guest may read the MSR_PLATFORM_INFO MSR. Otherwise,
6138 a #GP would be raised when the guest tries to access. Currently, this
6139 capability does not enable write permissions of this MSR for the guest.
6141 7.16 KVM_CAP_PPC_NESTED_HV
6142 --------------------------
6146 :Returns: 0 on success, -EINVAL when the implementation doesn't support
6147 nested-HV virtualization.
6149 HV-KVM on POWER9 and later systems allows for "nested-HV"
6150 virtualization, which provides a way for a guest VM to run guests that
6151 can run using the CPU's supervisor mode (privileged non-hypervisor
6152 state). Enabling this capability on a VM depends on the CPU having
6153 the necessary functionality and on the facility being enabled with a
6154 kvm-hv module parameter.
6156 7.17 KVM_CAP_EXCEPTION_PAYLOAD
6157 ------------------------------
6160 :Parameters: args[0] whether feature should be enabled or not
6162 With this capability enabled, CR2 will not be modified prior to the
6163 emulated VM-exit when L1 intercepts a #PF exception that occurs in
6164 L2. Similarly, for kvm-intel only, DR6 will not be modified prior to
6165 the emulated VM-exit when L1 intercepts a #DB exception that occurs in
6166 L2. As a result, when KVM_GET_VCPU_EVENTS reports a pending #PF (or
6167 #DB) exception for L2, exception.has_payload will be set and the
6168 faulting address (or the new DR6 bits*) will be reported in the
6169 exception_payload field. Similarly, when userspace injects a #PF (or
6170 #DB) into L2 using KVM_SET_VCPU_EVENTS, it is expected to set
6171 exception.has_payload and to put the faulting address - or the new DR6
6172 bits\ [#]_ - in the exception_payload field.
6174 This capability also enables exception.pending in struct
6175 kvm_vcpu_events, which allows userspace to distinguish between pending
6176 and injected exceptions.
6179 .. [#] For the new DR6 bits, note that bit 16 is set iff the #DB exception
6182 7.18 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
6184 :Architectures: x86, arm, arm64, mips
6185 :Parameters: args[0] whether feature should be enabled or not
6189 #define KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE (1 << 0)
6190 #define KVM_DIRTY_LOG_INITIALLY_SET (1 << 1)
6192 With KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE is set, KVM_GET_DIRTY_LOG will not
6193 automatically clear and write-protect all pages that are returned as dirty.
6194 Rather, userspace will have to do this operation separately using
6195 KVM_CLEAR_DIRTY_LOG.
6197 At the cost of a slightly more complicated operation, this provides better
6198 scalability and responsiveness for two reasons. First,
6199 KVM_CLEAR_DIRTY_LOG ioctl can operate on a 64-page granularity rather
6200 than requiring to sync a full memslot; this ensures that KVM does not
6201 take spinlocks for an extended period of time. Second, in some cases a
6202 large amount of time can pass between a call to KVM_GET_DIRTY_LOG and
6203 userspace actually using the data in the page. Pages can be modified
6204 during this time, which is inefficient for both the guest and userspace:
6205 the guest will incur a higher penalty due to write protection faults,
6206 while userspace can see false reports of dirty pages. Manual reprotection
6207 helps reducing this time, improving guest performance and reducing the
6208 number of dirty log false positives.
6210 With KVM_DIRTY_LOG_INITIALLY_SET set, all the bits of the dirty bitmap
6211 will be initialized to 1 when created. This also improves performance because
6212 dirty logging can be enabled gradually in small chunks on the first call
6213 to KVM_CLEAR_DIRTY_LOG. KVM_DIRTY_LOG_INITIALLY_SET depends on
6214 KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE (it is also only available on
6215 x86 and arm64 for now).
6217 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 was previously available under the name
6218 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT, but the implementation had bugs that make
6219 it hard or impossible to use it correctly. The availability of
6220 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 signals that those bugs are fixed.
6221 Userspace should not try to use KVM_CAP_MANUAL_DIRTY_LOG_PROTECT.
6223 7.19 KVM_CAP_PPC_SECURE_GUEST
6224 ------------------------------
6228 This capability indicates that KVM is running on a host that has
6229 ultravisor firmware and thus can support a secure guest. On such a
6230 system, a guest can ask the ultravisor to make it a secure guest,
6231 one whose memory is inaccessible to the host except for pages which
6232 are explicitly requested to be shared with the host. The ultravisor
6233 notifies KVM when a guest requests to become a secure guest, and KVM
6234 has the opportunity to veto the transition.
6236 If present, this capability can be enabled for a VM, meaning that KVM
6237 will allow the transition to secure guest mode. Otherwise KVM will
6238 veto the transition.
6240 7.20 KVM_CAP_HALT_POLL
6241 ----------------------
6245 :Parameters: args[0] is the maximum poll time in nanoseconds
6246 :Returns: 0 on success; -1 on error
6248 This capability overrides the kvm module parameter halt_poll_ns for the
6251 VCPU polling allows a VCPU to poll for wakeup events instead of immediately
6252 scheduling during guest halts. The maximum time a VCPU can spend polling is
6253 controlled by the kvm module parameter halt_poll_ns. This capability allows
6254 the maximum halt time to specified on a per-VM basis, effectively overriding
6255 the module parameter for the target VM.
6257 7.21 KVM_CAP_X86_USER_SPACE_MSR
6258 -------------------------------
6262 :Parameters: args[0] contains the mask of KVM_MSR_EXIT_REASON_* events to report
6263 :Returns: 0 on success; -1 on error
6265 This capability enables trapping of #GP invoking RDMSR and WRMSR instructions
6268 When a guest requests to read or write an MSR, KVM may not implement all MSRs
6269 that are relevant to a respective system. It also does not differentiate by
6272 To allow more fine grained control over MSR handling, user space may enable
6273 this capability. With it enabled, MSR accesses that match the mask specified in
6274 args[0] and trigger a #GP event inside the guest by KVM will instead trigger
6275 KVM_EXIT_X86_RDMSR and KVM_EXIT_X86_WRMSR exit notifications which user space
6276 can then handle to implement model specific MSR handling and/or user notifications
6277 to inform a user that an MSR was not handled.
6279 7.22 KVM_CAP_X86_BUS_LOCK_EXIT
6280 -------------------------------
6284 :Parameters: args[0] defines the policy used when bus locks detected in guest
6285 :Returns: 0 on success, -EINVAL when args[0] contains invalid bits
6287 Valid bits in args[0] are::
6289 #define KVM_BUS_LOCK_DETECTION_OFF (1 << 0)
6290 #define KVM_BUS_LOCK_DETECTION_EXIT (1 << 1)
6292 Enabling this capability on a VM provides userspace with a way to select
6293 a policy to handle the bus locks detected in guest. Userspace can obtain
6294 the supported modes from the result of KVM_CHECK_EXTENSION and define it
6295 through the KVM_ENABLE_CAP.
6297 KVM_BUS_LOCK_DETECTION_OFF and KVM_BUS_LOCK_DETECTION_EXIT are supported
6298 currently and mutually exclusive with each other. More bits can be added in
6301 With KVM_BUS_LOCK_DETECTION_OFF set, bus locks in guest will not cause vm exits
6302 so that no additional actions are needed. This is the default mode.
6304 With KVM_BUS_LOCK_DETECTION_EXIT set, vm exits happen when bus lock detected
6305 in VM. KVM just exits to userspace when handling them. Userspace can enforce
6306 its own throttling or other policy based mitigations.
6308 This capability is aimed to address the thread that VM can exploit bus locks to
6309 degree the performance of the whole system. Once the userspace enable this
6310 capability and select the KVM_BUS_LOCK_DETECTION_EXIT mode, KVM will set the
6311 KVM_RUN_BUS_LOCK flag in vcpu-run->flags field and exit to userspace. Concerning
6312 the bus lock vm exit can be preempted by a higher priority VM exit, the exit
6313 notifications to userspace can be KVM_EXIT_BUS_LOCK or other reasons.
6314 KVM_RUN_BUS_LOCK flag is used to distinguish between them.
6316 7.23 KVM_CAP_PPC_DAWR1
6317 ----------------------
6321 :Returns: 0 on success, -EINVAL when CPU doesn't support 2nd DAWR
6323 This capability can be used to check / enable 2nd DAWR feature provided
6324 by POWER10 processor.
6326 7.24 KVM_CAP_VM_COPY_ENC_CONTEXT_FROM
6327 -------------------------------------
6329 Architectures: x86 SEV enabled
6331 Parameters: args[0] is the fd of the source vm
6332 Returns: 0 on success; ENOTTY on error
6334 This capability enables userspace to copy encryption context from the vm
6335 indicated by the fd to the vm this is called on.
6337 This is intended to support in-guest workloads scheduled by the host. This
6338 allows the in-guest workload to maintain its own NPTs and keeps the two vms
6339 from accidentally clobbering each other with interrupts and the like (separate
6342 7.25 KVM_CAP_SGX_ATTRIBUTE
6343 ----------------------
6347 :Parameters: args[0] is a file handle of a SGX attribute file in securityfs
6348 :Returns: 0 on success, -EINVAL if the file handle is invalid or if a requested
6349 attribute is not supported by KVM.
6351 KVM_CAP_SGX_ATTRIBUTE enables a userspace VMM to grant a VM access to one or
6352 more priveleged enclave attributes. args[0] must hold a file handle to a valid
6353 SGX attribute file corresponding to an attribute that is supported/restricted
6354 by KVM (currently only PROVISIONKEY).
6356 The SGX subsystem restricts access to a subset of enclave attributes to provide
6357 additional security for an uncompromised kernel, e.g. use of the PROVISIONKEY
6358 is restricted to deter malware from using the PROVISIONKEY to obtain a stable
6359 system fingerprint. To prevent userspace from circumventing such restrictions
6360 by running an enclave in a VM, KVM prevents access to privileged attributes by
6363 See Documentation/x86/sgx/2.Kernel-internals.rst for more details.
6365 8. Other capabilities.
6366 ======================
6368 This section lists capabilities that give information about other
6369 features of the KVM implementation.
6371 8.1 KVM_CAP_PPC_HWRNG
6372 ---------------------
6376 This capability, if KVM_CHECK_EXTENSION indicates that it is
6377 available, means that the kernel has an implementation of the
6378 H_RANDOM hypercall backed by a hardware random-number generator.
6379 If present, the kernel H_RANDOM handler can be enabled for guest use
6380 with the KVM_CAP_PPC_ENABLE_HCALL capability.
6382 8.2 KVM_CAP_HYPERV_SYNIC
6383 ------------------------
6387 This capability, if KVM_CHECK_EXTENSION indicates that it is
6388 available, means that the kernel has an implementation of the
6389 Hyper-V Synthetic interrupt controller(SynIC). Hyper-V SynIC is
6390 used to support Windows Hyper-V based guest paravirt drivers(VMBus).
6392 In order to use SynIC, it has to be activated by setting this
6393 capability via KVM_ENABLE_CAP ioctl on the vcpu fd. Note that this
6394 will disable the use of APIC hardware virtualization even if supported
6395 by the CPU, as it's incompatible with SynIC auto-EOI behavior.
6397 8.3 KVM_CAP_PPC_RADIX_MMU
6398 -------------------------
6402 This capability, if KVM_CHECK_EXTENSION indicates that it is
6403 available, means that the kernel can support guests using the
6404 radix MMU defined in Power ISA V3.00 (as implemented in the POWER9
6407 8.4 KVM_CAP_PPC_HASH_MMU_V3
6408 ---------------------------
6412 This capability, if KVM_CHECK_EXTENSION indicates that it is
6413 available, means that the kernel can support guests using the
6414 hashed page table MMU defined in Power ISA V3.00 (as implemented in
6415 the POWER9 processor), including in-memory segment tables.
6420 :Architectures: mips
6422 This capability, if KVM_CHECK_EXTENSION on the main kvm handle indicates that
6423 it is available, means that full hardware assisted virtualization capabilities
6424 of the hardware are available for use through KVM. An appropriate
6425 KVM_VM_MIPS_* type must be passed to KVM_CREATE_VM to create a VM which
6428 If KVM_CHECK_EXTENSION on a kvm VM handle indicates that this capability is
6429 available, it means that the VM is using full hardware assisted virtualization
6430 capabilities of the hardware. This is useful to check after creating a VM with
6431 KVM_VM_MIPS_DEFAULT.
6433 The value returned by KVM_CHECK_EXTENSION should be compared against known
6434 values (see below). All other values are reserved. This is to allow for the
6435 possibility of other hardware assisted virtualization implementations which
6436 may be incompatible with the MIPS VZ ASE.
6438 == ==========================================================================
6439 0 The trap & emulate implementation is in use to run guest code in user
6440 mode. Guest virtual memory segments are rearranged to fit the guest in the
6441 user mode address space.
6443 1 The MIPS VZ ASE is in use, providing full hardware assisted
6444 virtualization, including standard guest virtual memory segments.
6445 == ==========================================================================
6450 :Architectures: mips
6452 This capability, if KVM_CHECK_EXTENSION on the main kvm handle indicates that
6453 it is available, means that the trap & emulate implementation is available to
6454 run guest code in user mode, even if KVM_CAP_MIPS_VZ indicates that hardware
6455 assisted virtualisation is also available. KVM_VM_MIPS_TE (0) must be passed
6456 to KVM_CREATE_VM to create a VM which utilises it.
6458 If KVM_CHECK_EXTENSION on a kvm VM handle indicates that this capability is
6459 available, it means that the VM is using trap & emulate.
6461 8.7 KVM_CAP_MIPS_64BIT
6462 ----------------------
6464 :Architectures: mips
6466 This capability indicates the supported architecture type of the guest, i.e. the
6467 supported register and address width.
6469 The values returned when this capability is checked by KVM_CHECK_EXTENSION on a
6470 kvm VM handle correspond roughly to the CP0_Config.AT register field, and should
6471 be checked specifically against known values (see below). All other values are
6474 == ========================================================================
6475 0 MIPS32 or microMIPS32.
6476 Both registers and addresses are 32-bits wide.
6477 It will only be possible to run 32-bit guest code.
6479 1 MIPS64 or microMIPS64 with access only to 32-bit compatibility segments.
6480 Registers are 64-bits wide, but addresses are 32-bits wide.
6481 64-bit guest code may run but cannot access MIPS64 memory segments.
6482 It will also be possible to run 32-bit guest code.
6484 2 MIPS64 or microMIPS64 with access to all address segments.
6485 Both registers and addresses are 64-bits wide.
6486 It will be possible to run 64-bit or 32-bit guest code.
6487 == ========================================================================
6489 8.9 KVM_CAP_ARM_USER_IRQ
6490 ------------------------
6492 :Architectures: arm, arm64
6494 This capability, if KVM_CHECK_EXTENSION indicates that it is available, means
6495 that if userspace creates a VM without an in-kernel interrupt controller, it
6496 will be notified of changes to the output level of in-kernel emulated devices,
6497 which can generate virtual interrupts, presented to the VM.
6498 For such VMs, on every return to userspace, the kernel
6499 updates the vcpu's run->s.regs.device_irq_level field to represent the actual
6500 output level of the device.
6502 Whenever kvm detects a change in the device output level, kvm guarantees at
6503 least one return to userspace before running the VM. This exit could either
6504 be a KVM_EXIT_INTR or any other exit event, like KVM_EXIT_MMIO. This way,
6505 userspace can always sample the device output level and re-compute the state of
6506 the userspace interrupt controller. Userspace should always check the state
6507 of run->s.regs.device_irq_level on every kvm exit.
6508 The value in run->s.regs.device_irq_level can represent both level and edge
6509 triggered interrupt signals, depending on the device. Edge triggered interrupt
6510 signals will exit to userspace with the bit in run->s.regs.device_irq_level
6511 set exactly once per edge signal.
6513 The field run->s.regs.device_irq_level is available independent of
6514 run->kvm_valid_regs or run->kvm_dirty_regs bits.
6516 If KVM_CAP_ARM_USER_IRQ is supported, the KVM_CHECK_EXTENSION ioctl returns a
6517 number larger than 0 indicating the version of this capability is implemented
6518 and thereby which bits in run->s.regs.device_irq_level can signal values.
6520 Currently the following bits are defined for the device_irq_level bitmap::
6522 KVM_CAP_ARM_USER_IRQ >= 1:
6524 KVM_ARM_DEV_EL1_VTIMER - EL1 virtual timer
6525 KVM_ARM_DEV_EL1_PTIMER - EL1 physical timer
6526 KVM_ARM_DEV_PMU - ARM PMU overflow interrupt signal
6528 Future versions of kvm may implement additional events. These will get
6529 indicated by returning a higher number from KVM_CHECK_EXTENSION and will be
6532 8.10 KVM_CAP_PPC_SMT_POSSIBLE
6533 -----------------------------
6537 Querying this capability returns a bitmap indicating the possible
6538 virtual SMT modes that can be set using KVM_CAP_PPC_SMT. If bit N
6539 (counting from the right) is set, then a virtual SMT mode of 2^N is
6542 8.11 KVM_CAP_HYPERV_SYNIC2
6543 --------------------------
6547 This capability enables a newer version of Hyper-V Synthetic interrupt
6548 controller (SynIC). The only difference with KVM_CAP_HYPERV_SYNIC is that KVM
6549 doesn't clear SynIC message and event flags pages when they are enabled by
6550 writing to the respective MSRs.
6552 8.12 KVM_CAP_HYPERV_VP_INDEX
6553 ----------------------------
6557 This capability indicates that userspace can load HV_X64_MSR_VP_INDEX msr. Its
6558 value is used to denote the target vcpu for a SynIC interrupt. For
6559 compatibilty, KVM initializes this msr to KVM's internal vcpu index. When this
6560 capability is absent, userspace can still query this msr's value.
6562 8.13 KVM_CAP_S390_AIS_MIGRATION
6563 -------------------------------
6565 :Architectures: s390
6568 This capability indicates if the flic device will be able to get/set the
6569 AIS states for migration via the KVM_DEV_FLIC_AISM_ALL attribute and allows
6570 to discover this without having to create a flic device.
6572 8.14 KVM_CAP_S390_PSW
6573 ---------------------
6575 :Architectures: s390
6577 This capability indicates that the PSW is exposed via the kvm_run structure.
6579 8.15 KVM_CAP_S390_GMAP
6580 ----------------------
6582 :Architectures: s390
6584 This capability indicates that the user space memory used as guest mapping can
6585 be anywhere in the user memory address space, as long as the memory slots are
6586 aligned and sized to a segment (1MB) boundary.
6588 8.16 KVM_CAP_S390_COW
6589 ---------------------
6591 :Architectures: s390
6593 This capability indicates that the user space memory used as guest mapping can
6594 use copy-on-write semantics as well as dirty pages tracking via read-only page
6597 8.17 KVM_CAP_S390_BPB
6598 ---------------------
6600 :Architectures: s390
6602 This capability indicates that kvm will implement the interfaces to handle
6603 reset, migration and nested KVM for branch prediction blocking. The stfle
6604 facility 82 should not be provided to the guest without this capability.
6606 8.18 KVM_CAP_HYPERV_TLBFLUSH
6607 ----------------------------
6611 This capability indicates that KVM supports paravirtualized Hyper-V TLB Flush
6613 HvFlushVirtualAddressSpace, HvFlushVirtualAddressSpaceEx,
6614 HvFlushVirtualAddressList, HvFlushVirtualAddressListEx.
6616 8.19 KVM_CAP_ARM_INJECT_SERROR_ESR
6617 ----------------------------------
6619 :Architectures: arm, arm64
6621 This capability indicates that userspace can specify (via the
6622 KVM_SET_VCPU_EVENTS ioctl) the syndrome value reported to the guest when it
6623 takes a virtual SError interrupt exception.
6624 If KVM advertises this capability, userspace can only specify the ISS field for
6625 the ESR syndrome. Other parts of the ESR, such as the EC are generated by the
6626 CPU when the exception is taken. If this virtual SError is taken to EL1 using
6627 AArch64, this value will be reported in the ISS field of ESR_ELx.
6629 See KVM_CAP_VCPU_EVENTS for more details.
6631 8.20 KVM_CAP_HYPERV_SEND_IPI
6632 ----------------------------
6636 This capability indicates that KVM supports paravirtualized Hyper-V IPI send
6638 HvCallSendSyntheticClusterIpi, HvCallSendSyntheticClusterIpiEx.
6640 8.21 KVM_CAP_HYPERV_DIRECT_TLBFLUSH
6641 -----------------------------------
6645 This capability indicates that KVM running on top of Hyper-V hypervisor
6646 enables Direct TLB flush for its guests meaning that TLB flush
6647 hypercalls are handled by Level 0 hypervisor (Hyper-V) bypassing KVM.
6648 Due to the different ABI for hypercall parameters between Hyper-V and
6649 KVM, enabling this capability effectively disables all hypercall
6650 handling by KVM (as some KVM hypercall may be mistakenly treated as TLB
6651 flush hypercalls by Hyper-V) so userspace should disable KVM identification
6652 in CPUID and only exposes Hyper-V identification. In this case, guest
6653 thinks it's running on Hyper-V and only use Hyper-V hypercalls.
6655 8.22 KVM_CAP_S390_VCPU_RESETS
6656 -----------------------------
6658 :Architectures: s390
6660 This capability indicates that the KVM_S390_NORMAL_RESET and
6661 KVM_S390_CLEAR_RESET ioctls are available.
6663 8.23 KVM_CAP_S390_PROTECTED
6664 ---------------------------
6666 :Architectures: s390
6668 This capability indicates that the Ultravisor has been initialized and
6669 KVM can therefore start protected VMs.
6670 This capability governs the KVM_S390_PV_COMMAND ioctl and the
6671 KVM_MP_STATE_LOAD MP_STATE. KVM_SET_MP_STATE can fail for protected
6672 guests when the state change is invalid.
6674 8.24 KVM_CAP_STEAL_TIME
6675 -----------------------
6677 :Architectures: arm64, x86
6679 This capability indicates that KVM supports steal time accounting.
6680 When steal time accounting is supported it may be enabled with
6681 architecture-specific interfaces. This capability and the architecture-
6682 specific interfaces must be consistent, i.e. if one says the feature
6683 is supported, than the other should as well and vice versa. For arm64
6684 see Documentation/virt/kvm/devices/vcpu.rst "KVM_ARM_VCPU_PVTIME_CTRL".
6685 For x86 see Documentation/virt/kvm/msr.rst "MSR_KVM_STEAL_TIME".
6687 8.25 KVM_CAP_S390_DIAG318
6688 -------------------------
6690 :Architectures: s390
6692 This capability enables a guest to set information about its control program
6693 (i.e. guest kernel type and version). The information is helpful during
6694 system/firmware service events, providing additional data about the guest
6695 environments running on the machine.
6697 The information is associated with the DIAGNOSE 0x318 instruction, which sets
6698 an 8-byte value consisting of a one-byte Control Program Name Code (CPNC) and
6699 a 7-byte Control Program Version Code (CPVC). The CPNC determines what
6700 environment the control program is running in (e.g. Linux, z/VM...), and the
6701 CPVC is used for information specific to OS (e.g. Linux version, Linux
6704 If this capability is available, then the CPNC and CPVC can be synchronized
6705 between KVM and userspace via the sync regs mechanism (KVM_SYNC_DIAG318).
6707 8.26 KVM_CAP_X86_USER_SPACE_MSR
6708 -------------------------------
6712 This capability indicates that KVM supports deflection of MSR reads and
6713 writes to user space. It can be enabled on a VM level. If enabled, MSR
6714 accesses that would usually trigger a #GP by KVM into the guest will
6715 instead get bounced to user space through the KVM_EXIT_X86_RDMSR and
6716 KVM_EXIT_X86_WRMSR exit notifications.
6718 8.27 KVM_X86_SET_MSR_FILTER
6719 ---------------------------
6723 This capability indicates that KVM supports that accesses to user defined MSRs
6724 may be rejected. With this capability exposed, KVM exports new VM ioctl
6725 KVM_X86_SET_MSR_FILTER which user space can call to specify bitmaps of MSR
6726 ranges that KVM should reject access to.
6728 In combination with KVM_CAP_X86_USER_SPACE_MSR, this allows user space to
6729 trap and emulate MSRs that are outside of the scope of KVM as well as
6730 limit the attack surface on KVM's MSR emulation code.
6732 8.28 KVM_CAP_ENFORCE_PV_CPUID
6733 -----------------------------
6737 When enabled, KVM will disable paravirtual features provided to the
6738 guest according to the bits in the KVM_CPUID_FEATURES CPUID leaf
6739 (0x40000001). Otherwise, a guest may use the paravirtual features
6740 regardless of what has actually been exposed through the CPUID leaf.
6742 8.29 KVM_CAP_DIRTY_LOG_RING
6743 ---------------------------
6746 :Parameters: args[0] - size of the dirty log ring
6748 KVM is capable of tracking dirty memory using ring buffers that are
6749 mmaped into userspace; there is one dirty ring per vcpu.
6751 The dirty ring is available to userspace as an array of
6752 ``struct kvm_dirty_gfn``. Each dirty entry it's defined as::
6754 struct kvm_dirty_gfn {
6756 __u32 slot; /* as_id | slot_id */
6760 The following values are defined for the flags field to define the
6761 current state of the entry::
6763 #define KVM_DIRTY_GFN_F_DIRTY BIT(0)
6764 #define KVM_DIRTY_GFN_F_RESET BIT(1)
6765 #define KVM_DIRTY_GFN_F_MASK 0x3
6767 Userspace should call KVM_ENABLE_CAP ioctl right after KVM_CREATE_VM
6768 ioctl to enable this capability for the new guest and set the size of
6769 the rings. Enabling the capability is only allowed before creating any
6770 vCPU, and the size of the ring must be a power of two. The larger the
6771 ring buffer, the less likely the ring is full and the VM is forced to
6772 exit to userspace. The optimal size depends on the workload, but it is
6773 recommended that it be at least 64 KiB (4096 entries).
6775 Just like for dirty page bitmaps, the buffer tracks writes to
6776 all user memory regions for which the KVM_MEM_LOG_DIRTY_PAGES flag was
6777 set in KVM_SET_USER_MEMORY_REGION. Once a memory region is registered
6778 with the flag set, userspace can start harvesting dirty pages from the
6781 An entry in the ring buffer can be unused (flag bits ``00``),
6782 dirty (flag bits ``01``) or harvested (flag bits ``1X``). The
6783 state machine for the entry is as follows::
6785 dirtied harvested reset
6786 00 -----------> 01 -------------> 1X -------+
6789 +------------------------------------------+
6791 To harvest the dirty pages, userspace accesses the mmaped ring buffer
6792 to read the dirty GFNs. If the flags has the DIRTY bit set (at this stage
6793 the RESET bit must be cleared), then it means this GFN is a dirty GFN.
6794 The userspace should harvest this GFN and mark the flags from state
6795 ``01b`` to ``1Xb`` (bit 0 will be ignored by KVM, but bit 1 must be set
6796 to show that this GFN is harvested and waiting for a reset), and move
6797 on to the next GFN. The userspace should continue to do this until the
6798 flags of a GFN have the DIRTY bit cleared, meaning that it has harvested
6799 all the dirty GFNs that were available.
6801 It's not necessary for userspace to harvest the all dirty GFNs at once.
6802 However it must collect the dirty GFNs in sequence, i.e., the userspace
6803 program cannot skip one dirty GFN to collect the one next to it.
6805 After processing one or more entries in the ring buffer, userspace
6806 calls the VM ioctl KVM_RESET_DIRTY_RINGS to notify the kernel about
6807 it, so that the kernel will reprotect those collected GFNs.
6808 Therefore, the ioctl must be called *before* reading the content of
6811 The dirty ring can get full. When it happens, the KVM_RUN of the
6812 vcpu will return with exit reason KVM_EXIT_DIRTY_LOG_FULL.
6814 The dirty ring interface has a major difference comparing to the
6815 KVM_GET_DIRTY_LOG interface in that, when reading the dirty ring from
6816 userspace, it's still possible that the kernel has not yet flushed the
6817 processor's dirty page buffers into the kernel buffer (with dirty bitmaps, the
6818 flushing is done by the KVM_GET_DIRTY_LOG ioctl). To achieve that, one
6819 needs to kick the vcpu out of KVM_RUN using a signal. The resulting
6820 vmexit ensures that all dirty GFNs are flushed to the dirty rings.
6822 NOTE: the capability KVM_CAP_DIRTY_LOG_RING and the corresponding
6823 ioctl KVM_RESET_DIRTY_RINGS are mutual exclusive to the existing ioctls
6824 KVM_GET_DIRTY_LOG and KVM_CLEAR_DIRTY_LOG. After enabling
6825 KVM_CAP_DIRTY_LOG_RING with an acceptable dirty ring size, the virtual
6826 machine will switch to ring-buffer dirty page tracking and further
6827 KVM_GET_DIRTY_LOG or KVM_CLEAR_DIRTY_LOG ioctls will fail.
6829 8.30 KVM_CAP_XEN_HVM
6830 --------------------
6834 This capability indicates the features that Xen supports for hosting Xen
6835 PVHVM guests. Valid flags are::
6837 #define KVM_XEN_HVM_CONFIG_HYPERCALL_MSR (1 << 0)
6838 #define KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL (1 << 1)
6839 #define KVM_XEN_HVM_CONFIG_SHARED_INFO (1 << 2)
6840 #define KVM_XEN_HVM_CONFIG_RUNSTATE (1 << 2)
6842 The KVM_XEN_HVM_CONFIG_HYPERCALL_MSR flag indicates that the KVM_XEN_HVM_CONFIG
6843 ioctl is available, for the guest to set its hypercall page.
6845 If KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL is also set, the same flag may also be
6846 provided in the flags to KVM_XEN_HVM_CONFIG, without providing hypercall page
6847 contents, to request that KVM generate hypercall page content automatically
6848 and also enable interception of guest hypercalls with KVM_EXIT_XEN.
6850 The KVM_XEN_HVM_CONFIG_SHARED_INFO flag indicates the availability of the
6851 KVM_XEN_HVM_SET_ATTR, KVM_XEN_HVM_GET_ATTR, KVM_XEN_VCPU_SET_ATTR and
6852 KVM_XEN_VCPU_GET_ATTR ioctls, as well as the delivery of exception vectors
6853 for event channel upcalls when the evtchn_upcall_pending field of a vcpu's
6856 The KVM_XEN_HVM_CONFIG_RUNSTATE flag indicates that the runstate-related
6857 features KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADDR/_CURRENT/_DATA/_ADJUST are
6858 supported by the KVM_XEN_VCPU_SET_ATTR/KVM_XEN_VCPU_GET_ATTR ioctls.
6860 8.31 KVM_CAP_PPC_MULTITCE
6861 -------------------------
6863 :Capability: KVM_CAP_PPC_MULTITCE
6867 This capability means the kernel is capable of handling hypercalls
6868 H_PUT_TCE_INDIRECT and H_STUFF_TCE without passing those into the user
6869 space. This significantly accelerates DMA operations for PPC KVM guests.
6870 User space should expect that its handlers for these hypercalls
6871 are not going to be called if user space previously registered LIOBN
6872 in KVM (via KVM_CREATE_SPAPR_TCE or similar calls).
6874 In order to enable H_PUT_TCE_INDIRECT and H_STUFF_TCE use in the guest,
6875 user space might have to advertise it for the guest. For example,
6876 IBM pSeries (sPAPR) guest starts using them if "hcall-multi-tce" is
6877 present in the "ibm,hypertas-functions" device-tree property.
6879 The hypercalls mentioned above may or may not be processed successfully
6880 in the kernel based fast path. If they can not be handled by the kernel,
6881 they will get passed on to user space. So user space still has to have
6882 an implementation for these despite the in kernel acceleration.
6884 This capability is always enabled.
6886 8.32 KVM_CAP_PTP_KVM
6887 --------------------
6889 :Architectures: arm64
6891 This capability indicates that the KVM virtual PTP service is
6892 supported in the host. A VMM can check whether the service is
6893 available to the guest on migration.