Commit 168d918f authored by Eric Hankland's avatar Eric Hankland Committed by Paolo Bonzini
Browse files

KVM: x86: Adjust counter sample period after a wrmsr 



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: default avatarEric Hankland <ehankland@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 7f42aa76

arch/x86/kvm/pmu.c

+2 −2
Original line number Diff line number Diff line
@@ -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*/

arch/x86/kvm/pmu.h

+9 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/vmx/pmu_intel.c

+6 −0
Original line number Diff line number Diff line
@@ -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)

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