[PATCH v3 09/17] KVM: x86: Set PEBS_UNAVAIL in IA32_MISC_ENABLE when PEBS is enabled

Like Xu
2021-01-04T13:28:04Z

The bit 12 represents "Processor Event Based Sampling Unavailable (RO)" :
1 = PEBS is not supported.
0 = PEBS is supported.

A write to this PEBS_UNAVL available bit will bring #GP(0) when guest PEBS
is enabled. Some PEBS drivers in guest may care about this bit.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
---
arch/x86/kvm/vmx/pmu_intel.c | 2 ++
arch/x86/kvm/x86.c | 4 ++++
2 files changed, 6 insertions(+)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index c04e12812797..99d9453e0176 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -426,6 +426,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
INTEL_PMC_MAX_GENERIC, pmu->nr_arch_fixed_counters);

if (vcpu->arch.perf_capabilities & PERF_CAP_PEBS_FORMAT) {
+ vcpu->arch.ia32_misc_enable_msr &= ~MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL;
if (vcpu->arch.perf_capabilities & PERF_CAP_PEBS_BASELINE) {
pmu->pebs_enable_mask = ~pmu->global_ctrl;
pmu->reserved_bits &= ~ICL_EVENTSEL_ADAPTIVE;
@@ -436,6 +437,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
} else
pmu->pebs_enable_mask = ~((1ull << pmu->nr_arch_gp_counters) - 1);
} else {
+ vcpu->arch.ia32_misc_enable_msr |= MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL;
vcpu->arch.perf_capabilities &= ~PERF_CAP_PEBS_MASK;
}

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a38ca932eec5..213368e47500 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3095,6 +3095,10 @@ 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 (!msr_info->host_initiated &&
+ (vcpu->arch.perf_capabilities & PERF_CAP_PEBS_FORMAT) &&
+ (data & MSR_IA32_MISC_ENABLE_PEBS_UNAVAIL))
+ return 1;
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