diff mbox series

[RESEND,v13,07/10] KVM: vmx/pmu: Reduce the overhead of LBR pass-through or cancellation

Message ID 20210108013704.134985-8-like.xu@linux.intel.com (mailing list archive)
State New, archived
Headers show
Series KVM: x86/pmu: Guest Last Branch Recording Enabling | expand

Commit Message

Like Xu Jan. 8, 2021, 1:37 a.m. UTC 
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(+)

Comments

Paolo Bonzini Jan. 26, 2021, 9:27 a.m. UTC | #1 
On 08/01/21 02:37, Like Xu wrote:
> +
> +	/* A flag to reduce the overhead of LBR pass-through or cancellation. */
> +	bool already_passthrough;

	/* True if LBRs are marked as not intercepted in the MSR bitmap  */
	bool msr_passthrough;

>   };
>   
>   /*
>
diff mbox series

Patch

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 863bb3fe73d4..b79244bd44bb 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;
 };
 
 /*