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

Mingwei Zhang
2024-01-24T00:39:11Z

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