From: Like Xu <like.xu.linux@gmail.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 07/12] KVM: x86/cpuid: Use fast return for cpuid "0xa" leaf when !enable_pmu
Date: Tue, 14 Feb 2023 13:07:52 +0800 [thread overview]
Message-ID: <20230214050757.9623-8-likexu@tencent.com> (raw)
In-Reply-To: <20230214050757.9623-1-likexu@tencent.com>
From: Like Xu <likexu@tencent.com>
Add an explicit !enable_pmu check as relying on kvm_pmu_cap to be
zeroed isn't obvious. 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 2a9f1e200dbc..b0bb5f9f5307 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -944,7 +944,7 @@ 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;
}
--
2.39.1
next prev parent reply other threads:[~2023-02-14 5:09 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-14 5:07 [PATCH v4 00/12] KVM: x86: Add AMD Guest PerfMonV2 PMU support Like Xu
2023-02-14 5:07 ` [PATCH v4 01/12] KVM: x86/pmu: Rename pmc_is_enabled() to pmc_is_globally_enabled() Like Xu
2023-02-14 5:07 ` [PATCH v4 02/12] KVM: VMX: Refactor intel_pmu_set_msr() to align with other set_msr() helpers Like Xu
2023-02-16 21:13 ` Sean Christopherson
2023-02-21 8:44 ` Like Xu
2023-03-23 7:43 ` Like Xu
2023-03-23 14:28 ` Sean Christopherson
2023-02-14 5:07 ` [PATCH v4 03/12] KVM: x86/pmu: Rewrite reprogram_counters() to improve performance Like Xu
2023-02-14 5:07 ` [PATCH v4 04/12] KVM: x86/pmu: Expose reprogram_counters() in pmu.h Like Xu
2023-02-14 5:07 ` [PATCH v4 05/12] KVM: x86/pmu: Error when user sets the GLOBAL_STATUS reserved bits Like Xu
2023-04-06 23:45 ` Sean Christopherson
2023-04-07 5:08 ` Like Xu
2023-04-07 15:43 ` Sean Christopherson
2023-02-14 5:07 ` [PATCH v4 06/12] KVM: x86/pmu: Make part of the Intel v2 PMU MSRs handling x86 generic Like Xu
2023-04-06 23:57 ` Sean Christopherson
2023-04-07 1:39 ` Sean Christopherson
2023-02-14 5:07 ` Like Xu [this message]
2023-04-06 23:59 ` [PATCH v4 07/12] KVM: x86/cpuid: Use fast return for cpuid "0xa" leaf when !enable_pmu Sean Christopherson
2023-02-14 5:07 ` [PATCH v4 08/12] KVM: x86/pmu: Disable vPMU if the minimum num of counters isn't met Like Xu
2023-04-07 0:06 ` Sean Christopherson
2023-04-07 0:23 ` Sean Christopherson
2023-02-14 5:07 ` [PATCH v4 09/12] KVM: x86/pmu: Forget PERFCTR_CORE if the min " Like Xu
2023-04-07 0:32 ` Sean Christopherson
2023-02-14 5:07 ` [PATCH v4 10/12] KVM: x86/cpuid: Add X86_FEATURE_PERFMON_V2 as a scattered flag Like Xu
2023-04-07 0:41 ` Sean Christopherson
2023-02-14 5:07 ` [PATCH v4 11/12] KVM: x86/svm/pmu: Add AMD PerfMonV2 support Like Xu
2023-04-07 1:35 ` Sean Christopherson
2023-04-07 7:08 ` Like Xu
2023-04-07 14:44 ` Sean Christopherson
2023-04-10 11:34 ` Like Xu
2023-02-14 5:07 ` [PATCH v4 12/12] KVM: x86/cpuid: Add AMD CPUID ExtPerfMonAndDbg leaf 0x80000022 Like Xu
2023-04-07 1:50 ` Sean Christopherson
2023-04-07 7:19 ` Like Xu
2023-04-07 2:02 ` [PATCH v4 00/12] KVM: x86: Add AMD Guest PerfMonV2 PMU support Sean Christopherson
2023-04-07 7:28 ` Like Xu
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