linux-kernel - [PATCH v4 04/16] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE

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Date:   Mon, 29 Mar 2021 13:41:25 +0800
From:   Like Xu <like.xu@...ux.intel.com>
To:     peterz@...radead.org, Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     eranian@...gle.com, andi@...stfloor.org, kan.liang@...ux.intel.com,
        wei.w.wang@...el.com, Wanpeng Li <wanpengli@...cent.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Like Xu <like.xu@...ux.intel.com>,
        Yao Yuan <yuan.yao@...el.com>
Subject: [PATCH v4 04/16] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE_EMON bit when vPMU is enabled

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@...el.com>
Signed-off-by: Like Xu <like.xu@...ux.intel.com>
---
 arch/x86/kvm/vmx/pmu_intel.c | 1 +
 arch/x86/kvm/x86.c           | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 9efc1a6b8693..d9dbebe03cae 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -488,6 +488,7 @@ 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);
 
 	pmu->nr_arch_gp_counters = min_t(int, eax.split.num_counters,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a9d95f90a048..536b64360b75 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3125,6 +3125,7 @@ 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