[PATCH v3 01/17] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE_EMON bit when vPMU is enabled

Like Xu
2021-01-04T13:24:05Z

On Intel platforms, software may uses IA32_MISC_ENABLE[7]
bit to detect whether the performance monitoring facility
is supported in the processor.

It's dependent on the PMU being enabled for the guest and
a write to this PMU available bit will be ignored.

Cc: Yao Yuan <yuan.yao@intel.com>
Signed-off-by: Like Xu <like.xu@linux.intel.com>
---
arch/x86/kvm/vmx/pmu_intel.c | 2 ++
arch/x86/kvm/x86.c | 1 +
2 files changed, 3 insertions(+)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index a886a47daebd..01c7d84ecf3e 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -339,6 +339,8 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
if (!pmu->version)
return;

+ vcpu->arch.ia32_misc_enable_msr |= MSR_IA32_MISC_ENABLE_EMON;
+
perf_get_x86_pmu_capability(&x86_pmu);
if (guest_cpuid_has(vcpu, X86_FEATURE_PDCM))
vcpu->arch.perf_capabilities = vmx_get_perf_capabilities();
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 648c677b12e9..87f97ffa9966 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3094,6 +3094,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
}
break;
case MSR_IA32_MISC_ENABLE:
+ data &= ~MSR_IA32_MISC_ENABLE_EMON;
if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT) &&
((vcpu->arch.ia32_misc_enable_msr ^ data) & MSR_IA32_MISC_ENABLE_MWAIT)) {
if (!guest_cpuid_has(vcpu, X86_FEATURE_XMM3))
--
2.29.2