When the LBR record 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 <[email protected]> --- arch/x86/kvm/vmx/pmu_intel.c | 1 + arch/x86/kvm/vmx/vmx.c | 12 ++++++++++++ arch/x86/kvm/vmx/vmx.h | 3 +++ 3 files changed, 16 insertions(+) diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index 85a675004cbb..75ba0444b4d1 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -614,6 +614,7 @@ static void intel_pmu_init(struct kvm_vcpu *vcpu) vmx_get_perf_capabilities() : 0; lbr_desc->lbr.nr = 0; lbr_desc->event = NULL; + lbr_desc->already_passthrough = false; } static void intel_pmu_reset(struct kvm_vcpu *vcpu) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 58a8af433741..800a26e3b571 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3880,12 +3880,24 @@ static void vmx_update_intercept_for_lbr_msrs(struct kvm_vcpu *vcpu, bool set) static inline void vmx_lbr_disable_passthrough(struct kvm_vcpu *vcpu) { + struct lbr_desc *lbr_desc = &to_vmx(vcpu)->lbr_desc; + + if (!lbr_desc->already_passthrough) + return; + vmx_update_intercept_for_lbr_msrs(vcpu, true); + lbr_desc->already_passthrough = false; } static inline void vmx_lbr_enable_passthrough(struct kvm_vcpu *vcpu) { + struct lbr_desc *lbr_desc = &to_vmx(vcpu)->lbr_desc; + + 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 c67ce758412e..c931463f75d9 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -102,6 +102,9 @@ 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
