linux-kernel - [PATCH 1/2] KVM: x86: Account fastpath-only VM-Exits in vCPU stats

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Date:   Thu,  1 Jun 2023 18:19:19 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] KVM: x86: Account fastpath-only VM-Exits in vCPU stats

Increment vcpu->stat.exits when handling a fastpath VM-Exit without
going through any part of the "slow" path.  Not bumping the exits stat
can result in wildly misleading exit counts, e.g. if the primary reason
the guest is exiting is to program the TSC deadline timer.

Fixes: 404d5d7bff0d ("KVM: X86: Introduce more exit_fastpath_completion enum values")
Cc: stable@...r.kernel.org
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ceb7c5e9cf9e..a609e39b2cb8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10754,6 +10754,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 			exit_fastpath = EXIT_FASTPATH_EXIT_HANDLED;
 			break;
 		}
+
+		/* Note, VM-Exits that go down the "slow" path are accounted below. */
+		++vcpu->stat.exits;
 	}
 
 	/*
-- 
2.41.0.rc2.161.g9c6817b8e7-goog