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KVM: x86: Fix perfctr WRMSR for running counters 

Correct the logic in intel_pmu_set_msr() for fixed and general purpose
counters. This was recently changed to set pmc->counter without taking
in to account the value of pmc_read_counter() which will be incorrect if
the counter is currently running and non-zero; this changes back to the
old logic which accounted for the value of currently running counters.

Signed-off-by: Eric Hankland <ehankland@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Eric Hankland 2020-01-27 13:22:56 -08:00 committed by Paolo Bonzini
parent a83502314c
commit 4400cf546b
1 changed files with 4 additions and 5 deletions
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9
arch/x86/kvm/vmx/pmu_intel.c
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@ -260,13 +260,12 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
break;
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0))) {
if (msr_info->host_initiated)
pmc->counter = data;
else
pmc->counter = (s32)data;
if (!msr_info->host_initiated)
data = (s64)(s32)data;
pmc->counter += data - pmc_read_counter(pmc);
return 0;
} else if ((pmc = get_fixed_pmc(pmu, msr))) {
pmc->counter = data;
pmc->counter += data - pmc_read_counter(pmc);
return 0;
} else if ((pmc = get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0))) {
if (data == pmc->eventsel)