diff options
Diffstat (limited to 'arch/x86/kvm/hyperv.h')
| -rw-r--r-- | arch/x86/kvm/hyperv.h | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h index 9f96414a31c5..f83b8db72b11 100644 --- a/arch/x86/kvm/hyperv.h +++ b/arch/x86/kvm/hyperv.h @@ -136,6 +136,33 @@ static inline bool kvm_hv_has_stimer_pending(struct kvm_vcpu *vcpu) HV_SYNIC_STIMER_COUNT); } +/* + * With HV_ACCESS_TSC_INVARIANT feature, invariant TSC (CPUID.80000007H:EDX[8]) + * is only observed after HV_X64_MSR_TSC_INVARIANT_CONTROL was written to. + */ +static inline bool kvm_hv_invtsc_suppressed(struct kvm_vcpu *vcpu) +{ + struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu); + + /* + * If Hyper-V's invariant TSC control is not exposed to the guest, + * the invariant TSC CPUID flag is not suppressed, Windows guests were + * observed to be able to handle it correctly. Going forward, VMMs are + * encouraged to enable Hyper-V's invariant TSC control when invariant + * TSC CPUID flag is set to make KVM's behavior match genuine Hyper-V. + */ + if (!hv_vcpu || + !(hv_vcpu->cpuid_cache.features_eax & HV_ACCESS_TSC_INVARIANT)) + return false; + + /* + * If Hyper-V's invariant TSC control is exposed to the guest, KVM is + * responsible for suppressing the invariant TSC CPUID flag if the + * Hyper-V control is not enabled. + */ + return !(to_kvm_hv(vcpu->kvm)->hv_invtsc_control & HV_EXPOSE_INVARIANT_TSC); +} + void kvm_hv_process_stimers(struct kvm_vcpu *vcpu); void kvm_hv_setup_tsc_page(struct kvm *kvm, |