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Subject[PATCH v14 07/11] KVM: vmx/pmu: Reduce the overhead of LBR pass-through or cancellation
Date
When the LBR records msrs has already been pass-through, there is no
need to call vmx_update_intercept_for_lbr_msrs() again and again, and
vice versa.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
---
arch/x86/kvm/vmx/pmu_intel.c | 13 +++++++++++++
arch/x86/kvm/vmx/vmx.h | 3 +++
2 files changed, 16 insertions(+)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 287fc14f0445..60f395e18446 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -550,6 +550,7 @@ static void intel_pmu_init(struct kvm_vcpu *vcpu)
vcpu->arch.perf_capabilities = 0;
lbr_desc->records.nr = 0;
lbr_desc->event = NULL;
+ lbr_desc->msr_passthrough = false;
}

static void intel_pmu_reset(struct kvm_vcpu *vcpu)
@@ -596,12 +597,24 @@ static void vmx_update_intercept_for_lbr_msrs(struct kvm_vcpu *vcpu, bool set)

static inline void vmx_disable_lbr_msrs_passthrough(struct kvm_vcpu *vcpu)
{
+ struct lbr_desc *lbr_desc = vcpu_to_lbr_desc(vcpu);
+
+ if (!lbr_desc->msr_passthrough)
+ return;
+
vmx_update_intercept_for_lbr_msrs(vcpu, true);
+ lbr_desc->msr_passthrough = false;
}

static inline void vmx_enable_lbr_msrs_passthrough(struct kvm_vcpu *vcpu)
{
+ struct lbr_desc *lbr_desc = vcpu_to_lbr_desc(vcpu);
+
+ if (lbr_desc->msr_passthrough)
+ return;
+
vmx_update_intercept_for_lbr_msrs(vcpu, false);
+ lbr_desc->msr_passthrough = true;
}

/*
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 863bb3fe73d4..4d6a2624a204 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -90,6 +90,9 @@ struct lbr_desc {
* The records may be inaccurate if the host reclaims the LBR.
*/
struct perf_event *event;
+
+ /* True if LBRs are marked as not intercepted in the MSR bitmap */
+ bool msr_passthrough;
};

/*
--
2.29.2
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