linux-kernel - [PATCH v3 1/2] KVM: x86: count actual tlb flushes

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Date:	Thu, 18 Sep 2014 12:38:36 -0400
From:	Liang Chen <liangchen.linux@...il.com>
To:	pbonzini@...hat.com
Cc:	rkrcmar@...hat.com, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Liang Chen <liangchen.linux@...il.com>
Subject: [PATCH v3 1/2] KVM: x86: count actual tlb flushes

From: Radim Krčmář <rkrcmar@...hat.com>

- we count KVM_REQ_TLB_FLUSH requests, not actual flushes
  (KVM can have multiple requests for one flush)
- flushes from kvm_flush_remote_tlbs aren't counted
- it's easy to make a direct request by mistake

Solve these by postponing the counting to kvm_check_request().

Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
Signed-off-by: Liang Chen <liangchen.linux@...il.com>
---
 arch/x86/kvm/mmu.c | 1 -
 arch/x86/kvm/x86.c | 4 +++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 9314678..b41fd97 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3452,7 +3452,6 @@ static void nonpaging_init_context(struct kvm_vcpu *vcpu,
 
 void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu)
 {
-	++vcpu->stat.tlb_flush;
 	kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_flush_tlb);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8f1e22d..9eb5458 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6017,8 +6017,10 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 		}
 		if (kvm_check_request(KVM_REQ_MMU_SYNC, vcpu))
 			kvm_mmu_sync_roots(vcpu);
-		if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu))
+		if (kvm_check_request(KVM_REQ_TLB_FLUSH, vcpu)) {
+			++vcpu->stat.tlb_flush;
 			kvm_x86_ops->tlb_flush(vcpu);
+		}
 		if (kvm_check_request(KVM_REQ_REPORT_TPR_ACCESS, vcpu)) {
 			vcpu->run->exit_reason = KVM_EXIT_TPR_ACCESS;
 			r = 0;
-- 
1.9.1

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