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KVM: x86: Adjust counter sample period after a wrmsr

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The sample_period of a counter tracks when that counter will
overflow and set global status/trigger a PMI. However this currently
only gets set when the initial counter is created or when a counter is
resumed; this updates the sample period after a wrmsr so running
counters will accurately reflect their new value.

Signed-off-by: Eric Hankland <ehankland@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Eric Hankland 2020-02-21 18:34:13 -08:00 committed by Paolo Bonzini
parent 7f42aa76d4
commit 168d918f26
3 changed files with 17 additions and 2 deletions
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4
arch/x86/kvm/pmu.c
View File

@ -111,7 +111,7 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
.config = config,
};
attr.sample_period = (-pmc->counter) & pmc_bitmask(pmc);
attr.sample_period = get_sample_period(pmc, pmc->counter);
if (in_tx)
attr.config |= HSW_IN_TX;
@ -158,7 +158,7 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc)
/* recalibrate sample period and check if it's accepted by perf core */
if (perf_event_period(pmc->perf_event,
(-pmc->counter) & pmc_bitmask(pmc)))
get_sample_period(pmc, pmc->counter)))
return false;
/* reuse perf_event to serve as pmc_reprogram_counter() does*/

9
arch/x86/kvm/pmu.h
View File

@ -129,6 +129,15 @@ static inline struct kvm_pmc *get_fixed_pmc(struct kvm_pmu *pmu, u32 msr)
return NULL;
}
static inline u64 get_sample_period(struct kvm_pmc *pmc, u64 counter_value)
{
u64 sample_period = (-counter_value) & pmc_bitmask(pmc);
if (!sample_period)
sample_period = pmc_bitmask(pmc) + 1;
return sample_period;
}
void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel);
void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 ctrl, int fixed_idx);
void reprogram_counter(struct kvm_pmu *pmu, int pmc_idx);

6
arch/x86/kvm/vmx/pmu_intel.c
View File

@ -263,9 +263,15 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if (!msr_info->host_initiated)
data = (s64)(s32)data;
pmc->counter += data - pmc_read_counter(pmc);
if (pmc->perf_event)
perf_event_period(pmc->perf_event,
get_sample_period(pmc, data));
return 0;
} else if ((pmc = get_fixed_pmc(pmu, msr))) {
pmc->counter += data - pmc_read_counter(pmc);
if (pmc->perf_event)
perf_event_period(pmc->perf_event,
get_sample_period(pmc, data));
return 0;
} else if ((pmc = get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0))) {
if (data == pmc->eventsel)