linux-kernel - [KVM x86 vPMU Patch 2/2] KVM: x86/vPMU: Fix unnecessary signed extension for AMD PERFCTRn

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Date:	Fri,  7 Aug 2015 15:53:30 -0400
From:	Wei Huang <wei@...hat.com>
To:	kvm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, pbonzini@...hat.com, gleb@...nel.org,
	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, joro@...tes.org, trivial@...nel.org,
	drjones@...hat.com
Subject: [KVM x86 vPMU Patch 2/2] KVM: x86/vPMU: Fix unnecessary signed extension for AMD PERFCTRn

According to AMD programmer's manual, AMD PERFCTRn is 64-bit MSR which,
unlike Intel perf counters, doesn't require signed extension. This
patch removes the unnecessary conversion in SVM vPMU code when PERFCTRn
is being updated.

Signed-off-by: Wei Huang <wei@...hat.com>
---
 arch/x86/kvm/pmu_amd.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/kvm/pmu_amd.c b/arch/x86/kvm/pmu_amd.c
index 886aa25..39b9112 100644
--- a/arch/x86/kvm/pmu_amd.c
+++ b/arch/x86/kvm/pmu_amd.c
@@ -133,8 +133,6 @@ static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	/* MSR_K7_PERFCTRn */
 	pmc = get_gp_pmc(pmu, msr, MSR_K7_PERFCTR0);
 	if (pmc) {
-		if (!msr_info->host_initiated)
-			data = (s64)data;
 		pmc->counter += data - pmc_read_counter(pmc);
 		return 0;
 	}
-- 
1.8.3.1

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