Commit 40ccb96d authored by Like Xu's avatar Like Xu Committed by Paolo Bonzini
Browse files

KVM: x86/pmu: Add pmc->intr to refactor kvm_perf_overflow{_intr}() 



Depending on whether intr should be triggered or not, KVM registers
two different event overflow callbacks in the perf_event context.

The code skeleton of these two functions is very similar, so
the pmc->intr can be stored into pmc from pmc_reprogram_counter()
which provides smaller instructions footprint against the
u-architecture branch predictor.

The __kvm_perf_overflow() can be called in non-nmi contexts
and a flag is needed to distinguish the caller context and thus
avoid a check on kvm_is_in_guest(), otherwise we might get
warnings from suspicious RCU or check_preemption_disabled().

Suggested-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarLike Xu <likexu@tencent.com>
Message-Id: <20211130074221.93635-5-likexu@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 6ed1298e

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -495,6 +495,7 @@ struct kvm_pmc { 
	 */

	 */

	u64 current_config;

	u64 current_config;

	bool is_paused;

	bool is_paused;

	bool intr;

};

};





struct kvm_pmu {

struct kvm_pmu {

arch/x86/kvm/pmu.c

+28 −30
Original line number Original line Diff line number Diff line
@@ -55,30 +55,20 @@ static void kvm_pmi_trigger_fn(struct irq_work *irq_work) 
	kvm_pmu_deliver_pmi(vcpu);

	kvm_pmu_deliver_pmi(vcpu);

}

}





static void kvm_perf_overflow(struct perf_event *perf_event,

static inline void __kvm_perf_overflow(struct kvm_pmc *pmc, bool in_pmi)

			      struct perf_sample_data *data,

			      struct pt_regs *regs)

{

{

	struct kvm_pmc *pmc = perf_event->overflow_handler_context;

	struct kvm_pmu *pmu = pmc_to_pmu(pmc);

	struct kvm_pmu *pmu = pmc_to_pmu(pmc);





	if (!test_and_set_bit(pmc->idx, pmu->reprogram_pmi)) {

	/* Ignore counters that have been reprogrammed already. */

		__set_bit(pmc->idx, (unsigned long *)&pmu->global_status);

	if (test_and_set_bit(pmc->idx, pmu->reprogram_pmi))

		kvm_make_request(KVM_REQ_PMU, pmc->vcpu);

		return;

	}

}



static void kvm_perf_overflow_intr(struct perf_event *perf_event,

				   struct perf_sample_data *data,

				   struct pt_regs *regs)

{

	struct kvm_pmc *pmc = perf_event->overflow_handler_context;

	struct kvm_pmu *pmu = pmc_to_pmu(pmc);





	if (!test_and_set_bit(pmc->idx, pmu->reprogram_pmi)) {

	__set_bit(pmc->idx, (unsigned long *)&pmu->global_status);

	__set_bit(pmc->idx, (unsigned long *)&pmu->global_status);

	kvm_make_request(KVM_REQ_PMU, pmc->vcpu);

	kvm_make_request(KVM_REQ_PMU, pmc->vcpu);





	if (!pmc->intr)

		return;



	/*

	/*

	 * Inject PMI. If vcpu was in a guest mode during NMI PMI

	 * Inject PMI. If vcpu was in a guest mode during NMI PMI

	 * can be ejected on a guest mode re-entry. Otherwise we can't

	 * can be ejected on a guest mode re-entry. Otherwise we can't
@@ -87,11 +77,19 @@ static void kvm_perf_overflow_intr(struct perf_event *perf_event, 
	 * woken up. So we should wake it, but this is impossible from

	 * woken up. So we should wake it, but this is impossible from

	 * NMI context. Do it from irq work instead.

	 * NMI context. Do it from irq work instead.

	 */

	 */

		if (!kvm_is_in_guest())

	if (in_pmi && !kvm_is_in_guest())

		irq_work_queue(&pmc_to_pmu(pmc)->irq_work);

		irq_work_queue(&pmc_to_pmu(pmc)->irq_work);

	else

	else

		kvm_make_request(KVM_REQ_PMI, pmc->vcpu);

		kvm_make_request(KVM_REQ_PMI, pmc->vcpu);

}

}



static void kvm_perf_overflow(struct perf_event *perf_event,

			      struct perf_sample_data *data,

			      struct pt_regs *regs)

{

	struct kvm_pmc *pmc = perf_event->overflow_handler_context;



	__kvm_perf_overflow(pmc, true);

}

}





static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,

static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
@@ -126,7 +124,6 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type, 
	}

	}





	event = perf_event_create_kernel_counter(&attr, -1, current,

	event = perf_event_create_kernel_counter(&attr, -1, current,

						 intr ? kvm_perf_overflow_intr :

						 kvm_perf_overflow, pmc);

						 kvm_perf_overflow, pmc);

	if (IS_ERR(event)) {

	if (IS_ERR(event)) {

		pr_debug_ratelimited("kvm_pmu: event creation failed %ld for pmc->idx = %d\n",

		pr_debug_ratelimited("kvm_pmu: event creation failed %ld for pmc->idx = %d\n",
@@ -138,6 +135,7 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type, 
	pmc_to_pmu(pmc)->event_count++;

	pmc_to_pmu(pmc)->event_count++;

	clear_bit(pmc->idx, pmc_to_pmu(pmc)->reprogram_pmi);

	clear_bit(pmc->idx, pmc_to_pmu(pmc)->reprogram_pmi);

	pmc->is_paused = false;

	pmc->is_paused = false;

	pmc->intr = intr;

}

}





static void pmc_pause_counter(struct kvm_pmc *pmc)

static void pmc_pause_counter(struct kvm_pmc *pmc)