From: Sean Christopherson <seanjc@google.com>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, Like Xu <like.xu.linux@gmail.com>
Subject: [PATCH v2 1/7] KVM: x86: Refresh PMU after writes to MSR_IA32_PERF_CAPABILITIES
Date: Wed, 3 Aug 2022 19:26:52 +0000 [thread overview]
Message-ID: <20220803192658.860033-2-seanjc@google.com> (raw)
In-Reply-To: <20220803192658.860033-1-seanjc@google.com>
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.
Note, KVM may do the "wrong" thing if userspace changes PERF_CAPABILITIES
after running the vCPU, i.e. after KVM_RUN. Similar to disallowing CPUID
changes after KVM_RUN, KVM should also disallow changing feature MSRs
after KVM_RUN to prevent unexpected behavior. That problem will be
addressed separately at it affects MSRs other than PERF_CAPABILITES.
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@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.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 33560bfa0cac..dc19298e7150 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3546,9 +3546,9 @@ 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:
--
2.37.1.559.g78731f0fdb-goog
next prev parent reply other threads:[~2022-08-03 19:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-03 19:26 [PATCH v2 0/7] KVM: x86: Intel PERF_CAPABILITIES fixes and cleanups Sean Christopherson
2022-08-03 19:26 ` Sean Christopherson [this message]
2022-08-03 19:26 ` [PATCH v2 2/7] perf/x86/core: Remove unnecessary stubs provided for KVM-only helpers Sean Christopherson
2022-08-04 8:49 ` Like Xu
2022-08-04 15:07 ` Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 3/7] perf/x86/core: Drop the unnecessary return value from x86_perf_get_lbr() Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 4/7] KVM: VMX: Advertise PMU LBRs if and only if perf supports LBRs Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 5/7] KVM: VMX: Use proper type-safe functions for vCPU => LBRs helpers Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 6/7] KVM: VMX: Adjust number of LBR records for PERF_CAPABILITIES at refresh Sean Christopherson
2022-08-03 19:26 ` [PATCH v2 7/7] KVM: VMX: Simplify capability check when handling PERF_CAPABILITIES write Sean Christopherson
2022-08-04 7:52 ` Like Xu
2022-08-04 15:00 ` Sean Christopherson
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