On 22/02/20 03:34, Eric Hankland wrote:
> 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@xxxxxxxxxx>
> ---
> arch/x86/kvm/pmu.c | 4 ++--
> arch/x86/kvm/pmu.h | 8 ++++++++
> arch/x86/kvm/vmx/pmu_intel.c | 6 ++++++
> 3 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
> index bcc6a73d6628..d1f8ca57d354 100644
> --- a/arch/x86/kvm/pmu.c
> +++ b/arch/x86/kvm/pmu.c
> @@ -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*/
> diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
> index 13332984b6d5..354b8598b6c1 100644
> --- a/arch/x86/kvm/pmu.h
> +++ b/arch/x86/kvm/pmu.h
> @@ -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);
> diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
> index fd21cdb10b79..e933541751fb 100644
> --- a/arch/x86/kvm/vmx/pmu_intel.c
> +++ b/arch/x86/kvm/vmx/pmu_intel.c
> @@ -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)
>
Queued, thanks.
Paolo
