From 4400cf546b4bb62d49198f6642add01bf6e9b34d Mon Sep 17 00:00:00 2001 From: Eric Hankland Date: Mon, 27 Jan 2020 13:22:56 -0800 Subject: [PATCH] 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 Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx/pmu_intel.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index 34a3a17..fd21cdb 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -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) -- 2.7.4