From: Like Xu <like.xu@linux.intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Jim Mattson <jmattson@google.com>,
kvm@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>,
linux-kernel@vger.kernel.org, Like Xu <like.xu@linux.intel.com>
Subject: [PATCH v13 07/10] KVM: vmx/pmu: Reduce the overhead of LBR pass-through or cancellation
Date: Sun, 26 Jul 2020 23:32:26 +0800 [thread overview]
Message-ID: <20200726153229.27149-9-like.xu@linux.intel.com> (raw)
In-Reply-To: <20200726153229.27149-1-like.xu@linux.intel.com>
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>
---
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 0358ceea34d4..08d195e08deb 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)
@@ -611,12 +612,24 @@ 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 dd029b57215c..f95d61942a1c 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -112,6 +112,9 @@ 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
next prev parent reply other threads:[~2020-07-26 15:35 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-26 15:32 [PATCH v13 00/10] Guest Last Branch Recording Enabling (KVM part) Like Xu
2020-07-26 15:32 ` [PATCH v13 01/10] KVM: x86: Move common set/get handler of MSR_IA32_DEBUGCTLMSR to VMX Like Xu
2020-07-26 15:32 ` [PATCH] target/i386: add -cpu,lbr=true support to enable guest LBR Like Xu
2020-07-26 15:32 ` Like Xu
2020-09-24 22:05 ` Eduardo Habkost
2020-09-24 22:05 ` Eduardo Habkost
2020-09-28 14:51 ` Xu, Like
2020-09-28 15:41 ` Eduardo Habkost
2020-09-28 15:41 ` Eduardo Habkost
2020-09-29 6:24 ` Xu, Like
2020-09-29 6:24 ` Xu, Like
2020-07-26 15:32 ` [PATCH v13 02/10] KVM: x86/vmx: Make vmx_set_intercept_for_msr() non-static and expose it Like Xu
2020-09-29 3:13 ` Sean Christopherson
2020-09-29 7:12 ` Xu, Like
2020-07-26 15:32 ` [PATCH v13 03/10] KVM: vmx/pmu: Initialize vcpu perf_capabilities once in intel_pmu_init() Like Xu
2020-07-26 15:32 ` [PATCH v13 04/10] KVM: vmx/pmu: Clear PMU_CAP_LBR_FMT when guest LBR is disabled Like Xu
2020-07-26 15:32 ` [PATCH v13 05/10] KVM: vmx/pmu: Create a guest LBR event when vcpu sets DEBUGCTLMSR_LBR Like Xu
2020-07-26 15:32 ` [PATCH v13 06/10] KVM: vmx/pmu: Pass-through LBR msrs to when the guest LBR event is ACTIVE Like Xu
2020-07-26 15:32 ` Like Xu [this message]
2020-07-26 15:32 ` [PATCH v13 08/10] KVM: vmx/pmu: Emulate legacy freezing LBRs on virtual PMI Like Xu
2020-07-26 15:32 ` [PATCH v13 09/10] KVM: vmx/pmu: Expose LBR_FMT in the MSR_IA32_PERF_CAPABILITIES Like Xu
2020-07-26 15:32 ` [PATCH v13 10/10] KVM: vmx/pmu: Release guest LBR event via lazy release mechanism Like Xu
2020-08-14 8:48 ` [PATCH v13 00/10] Guest Last Branch Recording Enabling (KVM part) Xu, Like
2020-09-04 1:57 ` Xu, Like
2020-09-30 2:23 ` Xu, Like
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