linux-kernel - [PATCH 1/3] KVM: x86: Refresh PMU after writes to MSR_IA32_PERF

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Message-Id: <20220727233424.2968356-2-seanjc@google.com>
Date:   Wed, 27 Jul 2022 23:34:22 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Like Xu <like.xu.linux@...il.com>
Subject: [PATCH 1/3] KVM: x86: Refresh PMU after writes to MSR_IA32_PERF_CAPABILITIES

Refresh the PMU if userspace modifies MSR_IA32_PERF_CAPABILITIES.  KVM
consumes the vCPU's PERF_CAPABILITIES when enumerating PEBS support, but
relies on CPUID updates to refresh the PMU.  I.e. KVM will do the wrong
thing if userspace stuffs PERF_CAPABILITIES _after_ setting guest CPUID.

Opportunistically fix a curly-brace indentation.

Fixes: c59a1f106f5c ("KVM: x86/pmu: Add IA32_PEBS_ENABLE MSR emulation for extended PEBS")
Cc: Like Xu <like.xu.linux@...il.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5366f884e9a7..362c538285db 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3543,9 +3543,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 			return 1;
 
 		vcpu->arch.perf_capabilities = data;
-
+		kvm_pmu_refresh(vcpu);
 		return 0;
-		}
+	}
 	case MSR_EFER:
 		return set_efer(vcpu, msr_info);
 	case MSR_K7_HWCR:
-- 
2.37.1.359.gd136c6c3e2-goog