linux-kernel - [PATCH v5 8/8] KVM: x86: Directly query supported PERF

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Message-ID: <20221006000314.73240-9-seanjc@google.com>
Date:   Thu,  6 Oct 2022 00:03:14 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Like Xu <like.xu.linux@...il.com>
Subject: [PATCH v5 8/8] KVM: x86: Directly query supported PERF_CAPABILITIES
 for WRMSR checks

Use kvm_caps.supported_perf_cap directly instead of bouncing through
kvm_get_msr_feature() when checking the incoming value for writes to
PERF_CAPABILITIES.

Note, kvm_get_msr_feature() is guaranteed to succeed when getting
PERF_CAPABILITIES, i.e. dropping that check is a nop.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9443ddb358e6..3afe5f4b1a40 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3568,20 +3568,15 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 			return 1;
 		vcpu->arch.arch_capabilities = data;
 		break;
-	case MSR_IA32_PERF_CAPABILITIES: {
-		struct kvm_msr_entry msr_ent = {.index = msr, .data = 0};
-
+	case MSR_IA32_PERF_CAPABILITIES:
 		if (!msr_info->host_initiated)
 			return 1;
-		if (kvm_get_msr_feature(&msr_ent))
-			return 1;
-		if (data & ~msr_ent.data)
+		if (data & ~kvm_caps.supported_perf_cap)
 			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:
-- 
2.38.0.rc1.362.ged0d419d3c-goog