Avi Kivity [Tue, 1 Sep 2009 09:34:07 +0000 (12:34 +0300)]
KVM: Use thread debug register storage instead of kvm specific data
Instead of saving the debug registers from the processor to a kvm data
structure, rely in the debug registers stored in the thread structure.
This allows us not to save dr6 and dr7.
Reduces lightweight vmexit cost by 350 cycles, or 11 percent.
Marcelo Tosatti [Tue, 25 Aug 2009 04:13:10 +0000 (01:13 -0300)]
KVM guest: do not batch pte updates from interrupt context
Commit b8bcfe997e4 made paravirt pte updates synchronous in interrupt
context.
Unfortunately the KVM pv mmu code caches the lazy/nonlazy mode
internally, so a pte update from interrupt context during a lazy mmu
operation can be batched while it should be performed synchronously.
The use of __pa() to calculate the address of a C-visible symbol
is wrong, and can lead to unpredictable results. See arch/x86/include/asm/page.h
for details.
It should be replaced with __pa_symbol(), that does the correct math here,
by taking relocations into account. This ensures the correct wallclock data
structure physical address is passed to the hypervisor.
Cc: stable@kernel.org Signed-off-by: Glauber Costa <glommer@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Gleb Natapov [Thu, 27 Aug 2009 15:41:30 +0000 (18:41 +0300)]
KVM: VMX: Fix cr8 exiting control clobbering by EPT
Don't call adjust_vmx_controls() two times for the same control.
It restores options that were dropped earlier. This loses us the cr8
exit control, which causes a massive performance regression Windows x64.
Cc: stable@kernel.org Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Anthony Liguori [Tue, 11 Aug 2009 20:57:59 +0000 (15:57 -0500)]
KVM: When switching to a vm8086 task, load segments as 16-bit
According to 16.2.5 in the SDM, eflags.vm in the tss is consulted before loading
and new segments. If eflags.vm == 1, then the segments are treated as 16-bit
segments. The LDTR and TR are not normally available in vm86 mode so if they
happen to somehow get loaded, they need to be treated as 32-bit segments.
This fixes an invalid vmentry failure in a custom OS that was happening after
a task switch into vm8086 mode. Since the segments were being mistakenly
treated as 32-bit, we loaded garbage state.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Gleb Natapov [Sun, 9 Aug 2009 12:17:40 +0000 (15:17 +0300)]
KVM: Update cr8 intercept when APIC TPR is changed by userspace
Since on vcpu entry we do it only if apic is enabled we should do
it when TPR is changed while apic is disabled. This happens when windows
resets HW without setting TPR to zero.
Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Joerg Roedel [Fri, 7 Aug 2009 09:49:44 +0000 (11:49 +0200)]
KVM: SVM: move special nested exit handling to separate function
This patch moves the handling for special nested vmexits like #pf to a
separate function. This makes the kvm_override parameter obsolete and
makes the code more readable.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Joerg Roedel [Fri, 7 Aug 2009 09:49:43 +0000 (11:49 +0200)]
KVM: SVM: handle errors in vmrun emulation path appropriatly
If nested svm fails to load the msrpm the vmrun succeeds with the old
msrpm which is not correct. This patch changes the logic to roll back
to host mode in case the msrpm cannot be loaded.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Joerg Roedel [Fri, 7 Aug 2009 09:49:38 +0000 (11:49 +0200)]
KVM: SVM: get rid of nested_svm_vmexit_real
This patch is the starting point of removing nested_svm_do from the
nested svm code. The nested_svm_do function basically maps two guest
physical pages to host virtual addresses and calls a passed function
on it. This function pointer code flow is hard to read and not the
best technical solution here.
As a side effect this patch indroduces the nested_svm_[un]map helper
functions.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Joerg Roedel [Fri, 7 Aug 2009 09:49:36 +0000 (11:49 +0200)]
KVM: SVM: do nested vmexit in nested_svm_exit_handled
If this function returns true a nested vmexit is required. Move that
vmexit into the nested_svm_exit_handled function. This also simplifies
the handling of nested #pf intercepts in this function.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Acked-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Joerg Roedel [Fri, 7 Aug 2009 09:49:34 +0000 (11:49 +0200)]
KVM: SVM: cache nested intercepts
When the nested intercepts are cached we don't need to call
get_user_pages and/or map the nested vmcb on every nested #vmexit to
check who will handle the intercept.
Further this patch aligns the emulated svm behavior better to real
hardware.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Joerg Roedel [Fri, 7 Aug 2009 09:49:32 +0000 (11:49 +0200)]
KVM: SVM: complete interrupts after handling nested exits
The interrupt completion code must run after nested exits are handled
because not injected interrupts or exceptions may be handled by the l1
guest first.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Acked-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Joerg Roedel [Fri, 7 Aug 2009 09:49:31 +0000 (11:49 +0200)]
KVM: SVM: copy only necessary parts of the control area on vmrun/vmexit
The vmcb control area contains more then 800 bytes of reserved fields
which are unnecessarily copied. Fix this by introducing a copy
function which only copies the relevant part and saves time.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Acked-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
Joerg Roedel [Fri, 7 Aug 2009 09:49:28 +0000 (11:49 +0200)]
KVM: SVM: add helper functions for global interrupt flag
This patch makes the code easier to read when it comes to setting,
clearing and checking the status of the virtualized global
interrupt flag for the VCPU.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Gleb Natapov [Tue, 4 Aug 2009 12:30:28 +0000 (15:30 +0300)]
KVM: Call ack notifiers from PIC when guest OS acks an IRQ.
Currently they are called when irq vector is been delivered. Calling ack
notifiers at this point is wrong. Device assignment ack notifier enables
host interrupts, but guest not yet had a chance to clear interrupt
condition in a device.
Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Jan Kiszka [Mon, 3 Aug 2009 16:43:28 +0000 (18:43 +0200)]
KVM: x86: Disallow hypercalls for guest callers in rings > 0
So far unprivileged guest callers running in ring 3 can issue, e.g., MMU
hypercalls. Normally, such callers cannot provide any hand-crafted MMU
command structure as it has to be passed by its physical address, but
they can still crash the guest kernel by passing random addresses.
To close the hole, this patch considers hypercalls valid only if issued
from guest ring 0. This may still be relaxed on a per-hypercall base in
the future once required.
Cc: stable@kernel.org Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Avi Kivity <avi@redhat.com>
This patch adds support for shadow paging to the 1gb page table code in KVM.
With this code the guest can use 1gb pages even if the host does not support
them.
[ Marcelo: fix shadow page collision on pmd level if a guest 1gb page is mapped
with 4kb ptes on host level ]
This patch removes the largepage parameter from the rmap_add function.
Together with rmap_remove this function now uses the role.level field to
find determine if the page is a huge page.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Mikhail Ershov [Mon, 3 Aug 2009 11:58:25 +0000 (14:58 +0300)]
KVM: Align cr8 threshold when userspace changes cr8
Commit f0a3602c20 ("KVM: Move interrupt injection logic to x86.c") does not
update the cr8 intercept if the lapic is disabled, so when userspace updates
cr8, the cr8 threshold control is not updated and we are left with illegal
control fields.
n_requested_mmu_pages/n_free_mmu_pages are used by
kvm_mmu_change_mmu_pages to calculate the number of pages to zap.
alloc_mmu_pages, called from the vcpu initialization path, modifies this
variables without proper locking, which can result in a negative value
in kvm_mmu_change_mmu_pages (say, with cpu hotplug).
KVM: Reduce runnability interface with arch support code
Remove kvm_cpu_has_interrupt() and kvm_arch_interrupt_allowed() from
interface between general code and arch code. kvm_arch_vcpu_runnable()
checks for interrupts instead.
Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
ioeventfd is a mechanism to register PIO/MMIO regions to trigger an eventfd
signal when written to by a guest. Host userspace can register any
arbitrary IO address with a corresponding eventfd and then pass the eventfd
to a specific end-point of interest for handling.
Normal IO requires a blocking round-trip since the operation may cause
side-effects in the emulated model or may return data to the caller.
Therefore, an IO in KVM traps from the guest to the host, causes a VMX/SVM
"heavy-weight" exit back to userspace, and is ultimately serviced by qemu's
device model synchronously before returning control back to the vcpu.
However, there is a subclass of IO which acts purely as a trigger for
other IO (such as to kick off an out-of-band DMA request, etc). For these
patterns, the synchronous call is particularly expensive since we really
only want to simply get our notification transmitted asychronously and
return as quickly as possible. All the sychronous infrastructure to ensure
proper data-dependencies are met in the normal IO case are just unecessary
overhead for signalling. This adds additional computational load on the
system, as well as latency to the signalling path.
Therefore, we provide a mechanism for registration of an in-kernel trigger
point that allows the VCPU to only require a very brief, lightweight
exit just long enough to signal an eventfd. This also means that any
clients compatible with the eventfd interface (which includes userspace
and kernelspace equally well) can now register to be notified. The end
result should be a more flexible and higher performance notification API
for the backend KVM hypervisor and perhipheral components.
To test this theory, we built a test-harness called "doorbell". This
module has a function called "doorbell_ring()" which simply increments a
counter for each time the doorbell is signaled. It supports signalling
from either an eventfd, or an ioctl().
We then wired up two paths to the doorbell: One via QEMU via a registered
io region and through the doorbell ioctl(). The other is direct via
ioeventfd.
I didn't measure qemu-pio, because I have to figure out how to register a
PIO region with qemu's device model, and I got lazy. However, for now we
can extrapolate based on the data from the NULLIO runs of +2.56us for MMIO,
and -350ns for HC, we get:
Today kvm_io_bus_regsiter_dev() returns void and will internally BUG_ON
if it fails. We want to create dynamic MMIO/PIO entries driven from
userspace later in the series, so we need to enhance the code to be more
robust with the following changes:
1) Add a return value to the registration function
2) Fix up all the callsites to check the return code, handle any
failures, and percolate the error up to the caller.
3) Add an unregister function that collapses holes in the array
Signed-off-by: Gregory Haskins <ghaskins@novell.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Beth Kon [Tue, 7 Jul 2009 15:50:38 +0000 (11:50 -0400)]
KVM: PIT support for HPET legacy mode
When kvm is in hpet_legacy_mode, the hpet is providing the timer
interrupt and the pit should not be. So in legacy mode, the pit timer
is destroyed, but the *state* of the pit is maintained. So if kvm or
the guest tries to modify the state of the pit, this modification is
accepted, *except* that the timer isn't actually started. When we exit
hpet_legacy_mode, the current state of the pit (which is up to date
since we've been accepting modifications) is used to restart the pit
timer.
The saved_mode code in kvm_pit_load_count temporarily changes mode to
0xff in order to destroy the timer, but then restores the actual
value, again maintaining "current" state of the pit for possible later
reenablement.
[avi: add some reserved storage in the ioctl; make SET_PIT2 IOW]
[marcelo: fix memory corruption due to reserved storage]
Signed-off-by: Beth Kon <eak@us.ibm.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Andre Przywara [Thu, 2 Jul 2009 13:04:14 +0000 (15:04 +0200)]
KVM: fix MMIO_CONF_BASE MSR access
Some Windows versions check whether the BIOS has setup MMI/O for
config space accesses on AMD Fam10h CPUs, we say "no" by returning 0 on
reads and only allow disabling of MMI/O CfgSpace setup by igoring "0" writes.
Signed-off-by: Andre Przywara <andre.przywara@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
To my understanding, it became obsolete with the advent of the more
robust check in mmu_alloc_roots (89da4ff17f). Moreover, it prevents
the conceptually safe pattern
1. set sregs
2. register mem-slots
3. run vcpu
by setting a sticky triple fault during step 1.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Andre Przywara [Fri, 3 Jul 2009 14:00:14 +0000 (16:00 +0200)]
KVM: handle AMD microcode MSR
Windows 7 tries to update the CPU's microcode on some processors,
so we ignore the MSR write here. The patchlevel register is already handled
(returning 0), because the MSR number is the same as Intel's.
Signed-off-by: Andre Przywara <andre.przywara@amd.com> Signed-off-by: Avi Kivity <avi@redhat.com>
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