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

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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: Sean Christopherson <seanjc@google.com>
Message-Id: <20220923001355.3741194-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-09-23 00:13:53 +00:00 committed by Paolo Bonzini
parent f1c5651fda
commit dcbb816a28
1 changed files with 24 additions and 14 deletions
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38
arch/x86/kvm/pmu.c
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@ -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,
(eventsel & pmu->raw_event_mask),
!(eventsel & ARCH_PERFMON_EVENTSEL_USR),
!(eventsel & ARCH_PERFMON_EVENTSEL_OS),
eventsel & ARCH_PERFMON_EVENTSEL_INT);
/*
* 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))
return;
reprogram_complete:
clear_bit(pmc->idx, (unsigned long *)&pmc_to_pmu(pmc)->reprogram_pmi);
}
EXPORT_SYMBOL_GPL(reprogram_counter);