Commit dcbb816a authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/pmu: Clear "reprogram" bit if counter is disabled or disallowed 



When reprogramming a counter, clear the counter's "reprogram pending" bit
if the counter is disabled (by the guest) or is disallowed (by the
userspace filter).  In both cases, there's no need to re-attempt
programming on the next coincident KVM_REQ_PMU as enabling the counter by
either method will trigger reprogramming.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20220923001355.3741194-3-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent f1c5651f

arch/x86/kvm/pmu.c

+24 −14
Original line number Diff line number Diff line
@@ -150,9 +150,9 @@ static void kvm_perf_overflow(struct perf_event *perf_event, 
	__kvm_perf_overflow(pmc, true);

}



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

				  u64 config, bool exclude_user,

				  bool exclude_kernel, bool intr)

static int pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type, u64 config,

				 bool exclude_user, bool exclude_kernel,

				 bool intr)

{

	struct kvm_pmu *pmu = pmc_to_pmu(pmc);

	struct perf_event *event;
@@ -204,14 +204,14 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type, 
	if (IS_ERR(event)) {

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

			    PTR_ERR(event), pmc->idx);

		return;

		return PTR_ERR(event);

	}



	pmc->perf_event = event;

	pmc_to_pmu(pmc)->event_count++;

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

	pmc->is_paused = false;

	pmc->intr = intr || pebs;

	return 0;

}



static void pmc_pause_counter(struct kvm_pmc *pmc)
@@ -245,7 +245,6 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc) 
	perf_event_enable(pmc->perf_event);

	pmc->is_paused = false;



	clear_bit(pmc->idx, (unsigned long *)&pmc_to_pmu(pmc)->reprogram_pmi);

	return true;

}
@@ -303,10 +302,10 @@ void reprogram_counter(struct kvm_pmc *pmc) 
	pmc_pause_counter(pmc);



	if (!pmc_speculative_in_use(pmc) || !pmc_is_enabled(pmc))

		return;

		goto reprogram_complete;



	if (!check_pmu_event_filter(pmc))

		return;

		goto reprogram_complete;



	if (eventsel & ARCH_PERFMON_EVENTSEL_PIN_CONTROL)

		printk_once("kvm pmu: pin control bit is ignored\n");
@@ -324,16 +323,27 @@ void reprogram_counter(struct kvm_pmc *pmc) 
	}



	if (pmc->current_config == new_config && pmc_resume_counter(pmc))

		return;

		goto reprogram_complete;



	pmc_release_perf_event(pmc);



	pmc->current_config = new_config;

	pmc_reprogram_counter(pmc, PERF_TYPE_RAW,



	/*

	 * If reprogramming fails, e.g. due to contention, leave the counter's

	 * regprogram bit set, i.e. opportunistically try again on the next PMU

	 * refresh.  Don't make a new request as doing so can stall the guest

	 * if reprogramming repeatedly fails.

	 */

	if (pmc_reprogram_counter(pmc, PERF_TYPE_RAW,

				  (eventsel & pmu->raw_event_mask),

				  !(eventsel & ARCH_PERFMON_EVENTSEL_USR),

				  !(eventsel & ARCH_PERFMON_EVENTSEL_OS),

			      eventsel & ARCH_PERFMON_EVENTSEL_INT);

				  eventsel & ARCH_PERFMON_EVENTSEL_INT))

		return;



reprogram_complete:

	clear_bit(pmc->idx, (unsigned long *)&pmc_to_pmu(pmc)->reprogram_pmi);

}

EXPORT_SYMBOL_GPL(reprogram_counter);