From: Like Xu <like.xu@linux.intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
ak@linux.intel.com, wei.w.wang@intel.com,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Like Xu <like.xu@linux.intel.com>
Subject: [PATCH v12 10/11] KVM: vmx/pmu: Reduce the overhead of LBR pass-through or cancellation
Date: Sat, 13 Jun 2020 16:09:55 +0800 [thread overview]
Message-ID: <20200613080958.132489-11-like.xu@linux.intel.com> (raw)
In-Reply-To: <20200613080958.132489-1-like.xu@linux.intel.com>
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 <like.xu@linux.intel.com>
---
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
next prev parent reply other threads:[~2020-06-13 8:12 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-13 8:09 [PATCH v12 00/11] Guest Last Branch Recording Enabling Like Xu
2020-06-13 8:09 ` [PATCH v12 01/11] perf/x86: Fix variable types for LBR registers Like Xu
2020-11-09 6:34 ` Andi Kleen
2020-11-11 2:14 ` Xu, Like
2020-06-13 8:09 ` [PATCH v12 02/11] perf/x86/core: Refactor hw->idx checks and cleanup Like Xu
2020-06-13 8:09 ` [PATCH v12 03/11] perf/x86/lbr: Add interface to get LBR information Like Xu
2020-06-13 8:09 ` [PATCH v12 04/11] perf/x86: Add constraint to create guest LBR event without hw counter Like Xu
2020-06-13 8:09 ` [PATCH v12 05/11] perf/x86: Keep LBR records unchanged in host context for guest usage Like Xu
2020-06-13 8:09 ` [PATCH v12 06/11] KVM: vmx/pmu: Expose LBR to guest via MSR_IA32_PERF_CAPABILITIES Like Xu
2020-07-08 13:36 ` Andi Kleen
2020-07-08 14:38 ` Xu, Like
2020-06-13 8:09 ` [PATCH v12 07/11] KVM: vmx/pmu: Unmask LBR fields in the MSR_IA32_DEBUGCTLMSR emualtion Like Xu
2020-06-13 9:14 ` Xiaoyao Li
2020-06-13 9:42 ` Xu, Like
2020-07-07 20:21 ` Sean Christopherson
2020-07-08 1:37 ` Xiaoyao Li
2020-07-08 7:06 ` Xu, Like
2020-07-10 16:28 ` Sean Christopherson
2020-06-13 8:09 ` [PATCH v12 08/11] KVM: vmx/pmu: Pass-through LBR msrs when guest LBR event is scheduled Like Xu
2020-06-13 8:09 ` [PATCH v12 09/11] KVM: vmx/pmu: Emulate legacy freezing LBRs on virtual PMI Like Xu
2020-06-13 8:09 ` Like Xu [this message]
2020-06-13 8:09 ` [PATCH v12 11/11] KVM: vmx/pmu: Release guest LBR event via lazy release mechanism Like Xu
2020-06-13 8:09 ` [Qemu-devel] [PATCH 1/2] target/i386: define a new MSR based feature word - FEAT_PERF_CAPABILITIES Like Xu
2020-06-13 8:09 ` [Qemu-devel] [PATCH 2/2] target/i386: add -cpu,lbr=true support to enable guest LBR Like Xu
2020-06-23 13:13 ` [PATCH v12 00/11] Guest Last Branch Recording Enabling Like Xu
2020-07-01 2:38 ` Like Xu
2020-07-02 7:40 ` Peter Zijlstra
2020-07-02 13:11 ` Liang, Kan
2020-07-02 13:58 ` Peter Zijlstra
2020-07-03 7:56 ` Peter Zijlstra
2020-07-03 8:04 ` Xu, Like
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