From d7547c55cbe7471255ca51f14bcd4699f5eaabe5 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Wed, 8 May 2019 17:15:47 +0800 Subject: [PATCH] KVM: Introduce KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 The previous KVM_CAP_MANUAL_DIRTY_LOG_PROTECT has some problem which blocks the correct usage from userspace. Obsolete the old one and introduce a new capability bit for it. Suggested-by: Paolo Bonzini Signed-off-by: Peter Xu Signed-off-by: Paolo Bonzini --- Documentation/virtual/kvm/api.txt | 15 ++++++++++----- include/uapi/linux/kvm.h | 5 +++-- tools/testing/selftests/kvm/dirty_log_test.c | 4 ++-- virt/kvm/kvm_main.c | 4 ++-- 4 files changed, 17 insertions(+), 11 deletions(-) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 675cb0bea903..47a5eb00bc53 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -330,7 +330,7 @@ They must be less than the value that KVM_CHECK_EXTENSION returns for the KVM_CAP_MULTI_ADDRESS_SPACE capability. The bits in the dirty bitmap are cleared before the ioctl returns, unless -KVM_CAP_MANUAL_DIRTY_LOG_PROTECT is enabled. For more information, +KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is enabled. For more information, see the description of the capability. 4.9 KVM_SET_MEMORY_ALIAS @@ -3791,7 +3791,7 @@ to I/O ports. 4.117 KVM_CLEAR_DIRTY_LOG (vm ioctl) -Capability: KVM_CAP_MANUAL_DIRTY_LOG_PROTECT +Capability: KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 Architectures: x86 Type: vm ioctl Parameters: struct kvm_dirty_log (in) @@ -3824,10 +3824,10 @@ the address space for which you want to return the dirty bitmap. They must be less than the value that KVM_CHECK_EXTENSION returns for the KVM_CAP_MULTI_ADDRESS_SPACE capability. -This ioctl is mostly useful when KVM_CAP_MANUAL_DIRTY_LOG_PROTECT +This ioctl is mostly useful when KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is enabled; for more information, see the description of the capability. However, it can always be used as long as KVM_CHECK_EXTENSION confirms -that KVM_CAP_MANUAL_DIRTY_LOG_PROTECT is present. +that KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is present. 4.118 KVM_GET_SUPPORTED_HV_CPUID @@ -4780,7 +4780,7 @@ and injected exceptions. * For the new DR6 bits, note that bit 16 is set iff the #DB exception will clear DR6.RTM. -7.18 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT +7.18 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 Architectures: all Parameters: args[0] whether feature should be enabled or not @@ -4803,6 +4803,11 @@ while userspace can see false reports of dirty pages. Manual reprotection helps reducing this time, improving guest performance and reducing the number of dirty log false positives. +KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 was previously available under the name +KVM_CAP_MANUAL_DIRTY_LOG_PROTECT, but the implementation had bugs that make +it hard or impossible to use it correctly. The availability of +KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 signals that those bugs are fixed. +Userspace should not try to use KVM_CAP_MANUAL_DIRTY_LOG_PROTECT. 8. Other capabilities. ---------------------- diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 6d4ea4b6c922..d673734c46cb 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -986,8 +986,9 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_HYPERV_ENLIGHTENED_VMCS 163 #define KVM_CAP_EXCEPTION_PAYLOAD 164 #define KVM_CAP_ARM_VM_IPA_SIZE 165 -#define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT 166 +#define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT 166 /* Obsolete */ #define KVM_CAP_HYPERV_CPUID 167 +#define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 168 #ifdef KVM_CAP_IRQ_ROUTING @@ -1434,7 +1435,7 @@ struct kvm_enc_region { #define KVM_GET_NESTED_STATE _IOWR(KVMIO, 0xbe, struct kvm_nested_state) #define KVM_SET_NESTED_STATE _IOW(KVMIO, 0xbf, struct kvm_nested_state) -/* Available with KVM_CAP_MANUAL_DIRTY_LOG_PROTECT */ +/* Available with KVM_CAP_MANUAL_DIRTY_LOG_PROTECT_2 */ #define KVM_CLEAR_DIRTY_LOG _IOWR(KVMIO, 0xc0, struct kvm_clear_dirty_log) /* Available with KVM_CAP_HYPERV_CPUID */ diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c index 052fb5856df4..a29d1119ccb3 100644 --- a/tools/testing/selftests/kvm/dirty_log_test.c +++ b/tools/testing/selftests/kvm/dirty_log_test.c @@ -311,7 +311,7 @@ static void run_test(enum vm_guest_mode mode, unsigned long iterations, #ifdef USE_CLEAR_DIRTY_LOG struct kvm_enable_cap cap = {}; - cap.cap = KVM_CAP_MANUAL_DIRTY_LOG_PROTECT; + cap.cap = KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2; cap.args[0] = 1; vm_enable_cap(vm, &cap); #endif @@ -427,7 +427,7 @@ int main(int argc, char *argv[]) int opt, i; #ifdef USE_CLEAR_DIRTY_LOG - if (!kvm_check_cap(KVM_CAP_MANUAL_DIRTY_LOG_PROTECT)) { + if (!kvm_check_cap(KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2)) { fprintf(stderr, "KVM_CLEAR_DIRTY_LOG not available, skipping tests\n"); exit(KSFT_SKIP); } diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 7883e0ad07fe..f4e02cd8fa43 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3110,7 +3110,7 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) case KVM_CAP_CHECK_EXTENSION_VM: case KVM_CAP_ENABLE_CAP_VM: #ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT - case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT: + case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2: #endif return 1; #ifdef CONFIG_KVM_MMIO @@ -3148,7 +3148,7 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm, { switch (cap->cap) { #ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT - case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT: + case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2: if (cap->flags || (cap->args[0] & ~1)) return -EINVAL; kvm->manual_dirty_log_protect = cap->args[0]; -- 2.39.5