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@xxxxxxxxxxxxxxx>
---
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 6b3319dbfa72..72a6dd6ca0ac 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -562,6 +562,7 @@ static void intel_pmu_init(struct kvm_vcpu *vcpu)
vmx_get_perf_capabilities() : 0;
lbr_desc->records.nr = 0;
lbr_desc->event = NULL;
+ lbr_desc->already_passthrough = false;
}
static void intel_pmu_reset(struct kvm_vcpu *vcpu)
@@ -607,12 +608,24 @@ 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->already_passthrough)
+ return;
+
vmx_update_intercept_for_lbr_msrs(vcpu, true);
+ lbr_desc->already_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->already_passthrough)
+ return;
+
vmx_update_intercept_for_lbr_msrs(vcpu, false);
+ lbr_desc->already_passthrough = true;
}
/*
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 2bd866c5a4e4..1869f5090e40 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;
+
+ /* A flag to reduce the overhead of LBR pass-through or cancellation. */
+ bool already_passthrough;
};
/*
--
2.21.3
