diff options
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 23 | ||||
| -rw-r--r-- | arch/x86/kvm/svm/nested.c | 4 | ||||
| -rw-r--r-- | arch/x86/kvm/svm/svm.c | 5 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 6 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 4 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 6 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.h | 5 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 1 | ||||
| -rw-r--r-- | tools/include/uapi/linux/kvm.h | 1 |
9 files changed, 53 insertions, 2 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index f0d961436d0f..6be1ddedec49 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -7844,6 +7844,7 @@ Valid bits in args[0] are:: #define KVM_X86_DISABLE_EXITS_HLT (1 << 1) #define KVM_X86_DISABLE_EXITS_PAUSE (1 << 2) #define KVM_X86_DISABLE_EXITS_CSTATE (1 << 3) + #define KVM_X86_DISABLE_EXITS_APERFMPERF (1 << 4) Enabling this capability on a VM provides userspace with a way to no longer intercept some instructions for improved latency in some @@ -7854,6 +7855,28 @@ all such vmexits. Do not enable KVM_FEATURE_PV_UNHALT if you disable HLT exits. +Virtualizing the ``IA32_APERF`` and ``IA32_MPERF`` MSRs requires more +than just disabling APERF/MPERF exits. While both Intel and AMD +document strict usage conditions for these MSRs--emphasizing that only +the ratio of their deltas over a time interval (T0 to T1) is +architecturally defined--simply passing through the MSRs can still +produce an incorrect ratio. + +This erroneous ratio can occur if, between T0 and T1: + +1. The vCPU thread migrates between logical processors. +2. Live migration or suspend/resume operations take place. +3. Another task shares the vCPU's logical processor. +4. C-states lower than C0 are emulated (e.g., via HLT interception). +5. The guest TSC frequency doesn't match the host TSC frequency. + +Due to these complexities, KVM does not automatically associate this +passthrough capability with the guest CPUID bit, +``CPUID.6:ECX.APERFMPERF[bit 0]``. Userspace VMMs that deem this +mechanism adequate for virtualizing the ``IA32_APERF`` and +``IA32_MPERF`` MSRs must set the guest CPUID bit explicitly. + + 7.14 KVM_CAP_S390_HPAGE_1M -------------------------- diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 749f7b866ac8..b7fd2e869998 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -194,7 +194,7 @@ void recalc_intercepts(struct vcpu_svm *svm) * Hardcode the capacity of the array based on the maximum number of _offsets_. * MSRs are batched together, so there are fewer offsets than MSRs. */ -static int nested_svm_msrpm_merge_offsets[6] __ro_after_init; +static int nested_svm_msrpm_merge_offsets[7] __ro_after_init; static int nested_svm_nr_msrpm_merge_offsets __ro_after_init; typedef unsigned long nsvm_msrpm_merge_t; @@ -216,6 +216,8 @@ int __init nested_svm_init_msrpm_merge_offsets(void) MSR_IA32_SPEC_CTRL, MSR_IA32_PRED_CMD, MSR_IA32_FLUSH_CMD, + MSR_IA32_APERF, + MSR_IA32_MPERF, MSR_IA32_LASTBRANCHFROMIP, MSR_IA32_LASTBRANCHTOIP, MSR_IA32_LASTINTFROMIP, diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 1261447ffcdd..fedf68c63318 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -838,6 +838,11 @@ static void svm_recalc_msr_intercepts(struct kvm_vcpu *vcpu) svm_set_intercept_for_msr(vcpu, MSR_IA32_SYSENTER_ESP, MSR_TYPE_RW, guest_cpuid_is_intel_compatible(vcpu)); + if (kvm_aperfmperf_in_guest(vcpu->kvm)) { + svm_disable_intercept_for_msr(vcpu, MSR_IA32_APERF, MSR_TYPE_R); + svm_disable_intercept_for_msr(vcpu, MSR_IA32_MPERF, MSR_TYPE_R); + } + if (sev_es_guest(vcpu->kvm)) sev_es_recalc_msr_intercepts(vcpu); diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index c69df3aba8d1..b8ea1969113d 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -715,6 +715,12 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu, nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0, MSR_IA32_FLUSH_CMD, MSR_TYPE_W); + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0, + MSR_IA32_APERF, MSR_TYPE_R); + + nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0, + MSR_IA32_MPERF, MSR_TYPE_R); + kvm_vcpu_unmap(vcpu, &map); vmx->nested.force_msr_bitmap_recalc = false; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index b064e50c6e64..77bbb2b93418 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4084,6 +4084,10 @@ void vmx_recalc_msr_intercepts(struct kvm_vcpu *vcpu) vmx_disable_intercept_for_msr(vcpu, MSR_CORE_C6_RESIDENCY, MSR_TYPE_R); vmx_disable_intercept_for_msr(vcpu, MSR_CORE_C7_RESIDENCY, MSR_TYPE_R); } + if (kvm_aperfmperf_in_guest(vcpu->kvm)) { + vmx_disable_intercept_for_msr(vcpu, MSR_IA32_APERF, MSR_TYPE_R); + vmx_disable_intercept_for_msr(vcpu, MSR_IA32_MPERF, MSR_TYPE_R); + } /* PT MSRs can be passed through iff PT is exposed to the guest. */ if (vmx_pt_mode_is_host_guest()) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6dda7bf4c44c..912260e3725d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4577,6 +4577,9 @@ static u64 kvm_get_allowed_disable_exits(void) { u64 r = KVM_X86_DISABLE_EXITS_PAUSE; + if (boot_cpu_has(X86_FEATURE_APERFMPERF)) + r |= KVM_X86_DISABLE_EXITS_APERFMPERF; + if (!mitigate_smt_rsb) { r |= KVM_X86_DISABLE_EXITS_HLT | KVM_X86_DISABLE_EXITS_CSTATE; @@ -6613,7 +6616,8 @@ split_irqchip_unlock: if (!mitigate_smt_rsb && boot_cpu_has_bug(X86_BUG_SMT_RSB) && cpu_smt_possible() && - (cap->args[0] & ~KVM_X86_DISABLE_EXITS_PAUSE)) + (cap->args[0] & ~(KVM_X86_DISABLE_EXITS_PAUSE | + KVM_X86_DISABLE_EXITS_APERFMPERF))) pr_warn_once(SMT_RSB_MSG); kvm_disable_exits(kvm, cap->args[0]); diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 17ec8436e565..e77281b6e2b2 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -524,6 +524,11 @@ static inline bool kvm_cstate_in_guest(struct kvm *kvm) return kvm->arch.disabled_exits & KVM_X86_DISABLE_EXITS_CSTATE; } +static inline bool kvm_aperfmperf_in_guest(struct kvm *kvm) +{ + return kvm->arch.disabled_exits & KVM_X86_DISABLE_EXITS_APERFMPERF; +} + static inline bool kvm_notify_vmexit_enabled(struct kvm *kvm) { return kvm->arch.notify_vmexit_flags & KVM_X86_NOTIFY_VMEXIT_ENABLED; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 7a4c35ff03fe..aeb2ca10b190 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -644,6 +644,7 @@ struct kvm_ioeventfd { #define KVM_X86_DISABLE_EXITS_HLT (1 << 1) #define KVM_X86_DISABLE_EXITS_PAUSE (1 << 2) #define KVM_X86_DISABLE_EXITS_CSTATE (1 << 3) +#define KVM_X86_DISABLE_EXITS_APERFMPERF (1 << 4) /* for KVM_ENABLE_CAP */ struct kvm_enable_cap { diff --git a/tools/include/uapi/linux/kvm.h b/tools/include/uapi/linux/kvm.h index b6ae8ad8934b..eef57c117140 100644 --- a/tools/include/uapi/linux/kvm.h +++ b/tools/include/uapi/linux/kvm.h @@ -617,6 +617,7 @@ struct kvm_ioeventfd { #define KVM_X86_DISABLE_EXITS_HLT (1 << 1) #define KVM_X86_DISABLE_EXITS_PAUSE (1 << 2) #define KVM_X86_DISABLE_EXITS_CSTATE (1 << 3) +#define KVM_X86_DISABLE_EXITS_APERFMPERF (1 << 4) /* for KVM_ENABLE_CAP */ struct kvm_enable_cap { |