linux-kernel - [PATCH 3/6] KVM: x86/pmu: Stop calling kvm_pmu

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Message-ID: <20231023234000.2499267-4-seanjc@google.com>
Date:   Mon, 23 Oct 2023 16:39:57 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mingwei Zhang <mizhang@...gle.com>,
        Roman Kagan <rkagan@...zon.de>,
        Jim Mattson <jmattson@...gle.com>,
        Dapeng Mi <dapeng1.mi@...ux.intel.com>,
        Like Xu <like.xu.linux@...il.com>
Subject: [PATCH 3/6] KVM: x86/pmu: Stop calling kvm_pmu_reset() at RESET (it's redundant)

Drop kvm_vcpu_reset()'s call to kvm_pmu_reset(), the call is performed
only for RESET, which is really just the same thing as vCPU creation,
and kvm_arch_vcpu_create() *just* called kvm_pmu_init(), i.e. there can't
possibly be any work to do.

Unlike Intel, AMD's amd_pmu_refresh() does fill all_valid_pmc_idx even if
guest CPUID is empty, but everything that is at all dynamic is guaranteed
to be '0'/NULL, e.g. it should be impossible for KVM to have already
created a perf event.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/pmu.c | 2 +-
 arch/x86/kvm/pmu.h | 1 -
 arch/x86/kvm/x86.c | 1 -
 3 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index dc8e8e907cfb..458e836c6efe 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -657,7 +657,7 @@ int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	return 0;
 }
 
-void kvm_pmu_reset(struct kvm_vcpu *vcpu)
+static void kvm_pmu_reset(struct kvm_vcpu *vcpu)
 {
 	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
 	struct kvm_pmc *pmc;
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index a46aa9b25150..db9a12c0a2ef 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -243,7 +243,6 @@ bool kvm_pmu_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr);
 int kvm_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info);
 int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info);
 void kvm_pmu_refresh(struct kvm_vcpu *vcpu);
-void kvm_pmu_reset(struct kvm_vcpu *vcpu);
 void kvm_pmu_init(struct kvm_vcpu *vcpu);
 void kvm_pmu_cleanup(struct kvm_vcpu *vcpu);
 void kvm_pmu_destroy(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0c9686207996..c8ac83a7764e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12207,7 +12207,6 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 	}
 
 	if (!init_event) {
-		kvm_pmu_reset(vcpu);
 		vcpu->arch.smbase = 0x30000;
 
 		vcpu->arch.msr_misc_features_enables = 0;
-- 
2.42.0.758.gaed0368e0e-goog