From: Like Xu <like.xu.linux@gmail.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3 8/8] KVM: x86/cpuid: Use fast return for cpuid "0xa" leaf when !enable_pmu
Date: Fri, 11 Nov 2022 18:26:45 +0800 [thread overview]
Message-ID: <20221111102645.82001-9-likexu@tencent.com> (raw)
In-Reply-To: <20221111102645.82001-1-likexu@tencent.com>
From: Like Xu <likexu@tencent.com>
Although when !enable_pmu, KVM will have zero-padded kvm_pmu_cap to do
subsequent cpuid leaf assignments, one extra branch instruction saves
a few subsequent zero-assignment instructions, speeding things up a bit.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Like Xu <likexu@tencent.com>
---
arch/x86/kvm/cpuid.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index df551fa66ccc..719290ff6d77 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -922,7 +922,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
union cpuid10_eax eax;
union cpuid10_edx edx;
- if (!static_cpu_has(X86_FEATURE_ARCH_PERFMON)) {
+ if (!enable_pmu || !static_cpu_has(X86_FEATURE_ARCH_PERFMON)) {
entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
break;
}
--
2.38.1
next prev parent reply other threads:[~2022-11-11 10:28 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-11 10:26 [PATCH v3 0/8] KVM: x86: Add AMD Guest PerfMonV2 PMU support Like Xu
2022-11-11 10:26 ` [PATCH v3 1/8] KVM: x86/pmu: Rename pmc_is_enabled() to pmc_is_globally_enabled() Like Xu
2023-01-27 2:03 ` Sean Christopherson
2023-02-02 11:46 ` Like Xu
2022-11-11 10:26 ` [PATCH v3 2/8] KVM: VMX: Refactor intel_pmu_set_msr() to align with other set_msr() helpers Like Xu
2023-01-27 2:09 ` Sean Christopherson
2022-11-11 10:26 ` [PATCH v3 3/8] KVM: x86/pmu: Rewrite reprogram_counters() to improve performance Like Xu
2023-01-20 1:09 ` Sean Christopherson
2023-01-24 20:16 ` Sean Christopherson
2022-11-11 10:26 ` [PATCH v3 4/8] KVM: x86/pmu: Make part of the Intel v2 PMU MSRs handling x86 generic Like Xu
2022-11-11 10:26 ` [PATCH v3 5/8] KVM: x86/cpuid: Add X86_FEATURE_AMD_PMU_V2 as a KVM-only leaf entry Like Xu
2023-01-24 19:47 ` Sean Christopherson
2023-02-06 11:47 ` Like Xu
2023-02-10 1:32 ` Sean Christopherson
2022-11-11 10:26 ` [PATCH v3 6/8] KVM: x86/svm/pmu: Add AMD PerfMonV2 support Like Xu
2023-01-25 0:10 ` Sean Christopherson
2023-02-06 7:53 ` Like Xu
2023-02-06 22:22 ` Sean Christopherson
2022-11-11 10:26 ` [PATCH v3 7/8] KVM: x86/cpuid: Add AMD CPUID ExtPerfMonAndDbg leaf 0x80000022 Like Xu
2023-01-25 0:16 ` Sean Christopherson
2022-11-11 10:26 ` Like Xu [this message]
2023-01-20 1:11 ` [PATCH v3 8/8] KVM: x86/cpuid: Use fast return for cpuid "0xa" leaf when !enable_pmu Sean Christopherson
2022-12-06 8:32 ` [PATCH v3 0/8] KVM: x86: Add AMD Guest PerfMonV2 PMU support Like Xu
2023-01-20 1:13 ` Sean Christopherson
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