From: Paolo Bonzini pbonzini@redhat.com
[ Upstream commit 2924b52117b2812e9633d5ea337333299166d373 ]
According to the SDM, for MSR_IA32_PERFCTR0/1 "the lower-order 32 bits of each MSR may be written with any value, and the high-order 8 bits are sign-extended according to the value of bit 31", but the fixed counters in real hardware are limited to the width of the fixed counters ("bits beyond the width of the fixed-function counter are reserved and must be written as zeros"). Fix KVM to do the same.
Reported-by: Nadav Amit nadav.amit@gmail.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/pmu_intel.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/pmu_intel.c b/arch/x86/kvm/pmu_intel.c index 23a7c7ba377a..8fc07ea23344 100644 --- a/arch/x86/kvm/pmu_intel.c +++ b/arch/x86/kvm/pmu_intel.c @@ -235,11 +235,14 @@ 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)) || - (pmc = get_fixed_pmc(pmu, msr))) { - if (!msr_info->host_initiated) - data = (s64)(s32)data; - pmc->counter += data - pmc_read_counter(pmc); + if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0))) { + if (msr_info->host_initiated) + pmc->counter = data; + else + pmc->counter = (s32)data; + return 0; + } else if ((pmc = get_fixed_pmc(pmu, msr))) { + pmc->counter = data; return 0; } else if ((pmc = get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0))) { if (data == pmc->eventsel)