[PATCH 2/2] KVM: x86/pmu: Remove vcpu_get_perf_capabilities()

From: Mingwei Zhang <mizhang@google.com>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	 Aaron Lewis <aaronlewis@google.com>,
	Mingwei Zhang <mizhang@google.com>
Subject: [PATCH 2/2] KVM: x86/pmu: Remove vcpu_get_perf_capabilities()
Date: Wed, 24 Jan 2024 00:38:57 +0000	[thread overview]
Message-ID: <20240124003858.3954822-3-mizhang@google.com> (raw)
In-Reply-To: <20240124003858.3954822-1-mizhang@google.com>

Remove vcpu_get_perf_capabilities() helper and directly use the
vcpu->arch.perf_capabilities which now contains the true value of
IA32_PERF_CAPABILITIES if exposed to guest (and 0 otherwise). This should
slightly improve performance by avoiding the runtime check of
X86_FEATURE_PDCM.

Signed-off-by: Mingwei Zhang <mizhang@google.com>
---
 arch/x86/kvm/vmx/pmu_intel.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index a6216c874729..7cbee2d16ed9 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -158,17 +158,9 @@ static struct kvm_pmc *intel_rdpmc_ecx_to_pmc(struct kvm_vcpu *vcpu,
 	return &counters[array_index_nospec(idx, num_counters)];
 }
 
-static inline u64 vcpu_get_perf_capabilities(struct kvm_vcpu *vcpu)
-{
-	if (!guest_cpuid_has(vcpu, X86_FEATURE_PDCM))
-		return 0;
-
-	return vcpu->arch.perf_capabilities;
-}
-
 static inline bool fw_writes_is_enabled(struct kvm_vcpu *vcpu)
 {
-	return (vcpu_get_perf_capabilities(vcpu) & PMU_CAP_FW_WRITES) != 0;
+	return (vcpu->arch.perf_capabilities & PMU_CAP_FW_WRITES) != 0;
 }
 
 static inline struct kvm_pmc *get_fw_gp_pmc(struct kvm_pmu *pmu, u32 msr)
@@ -207,13 +199,13 @@ static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
 	case MSR_CORE_PERF_FIXED_CTR_CTRL:
 		return kvm_pmu_has_perf_global_ctrl(pmu);
 	case MSR_IA32_PEBS_ENABLE:
-		ret = vcpu_get_perf_capabilities(vcpu) & PERF_CAP_PEBS_FORMAT;
+		ret = vcpu->arch.perf_capabilities & PERF_CAP_PEBS_FORMAT;
 		break;
 	case MSR_IA32_DS_AREA:
 		ret = guest_cpuid_has(vcpu, X86_FEATURE_DS);
 		break;
 	case MSR_PEBS_DATA_CFG:
-		perf_capabilities = vcpu_get_perf_capabilities(vcpu);
+		perf_capabilities = vcpu->arch.perf_capabilities;
 		ret = (perf_capabilities & PERF_CAP_PEBS_BASELINE) &&
 			((perf_capabilities & PERF_CAP_PEBS_FORMAT) > 3);
 		break;
@@ -577,7 +569,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
 	bitmap_set(pmu->all_valid_pmc_idx,
 		INTEL_PMC_MAX_GENERIC, pmu->nr_arch_fixed_counters);
 
-	perf_capabilities = vcpu_get_perf_capabilities(vcpu);
+	perf_capabilities = vcpu->arch.perf_capabilities;
 	if (cpuid_model_is_consistent(vcpu) &&
 	    (perf_capabilities & PMU_CAP_LBR_FMT))
 		x86_perf_get_lbr(&lbr_desc->records);
-- 
2.43.0.429.g432eaa2c6b-goog

