From 40ccb96d5483c7ef773f50db15f82f0ab587cf8a Mon Sep 17 00:00:00 2001 From: Like Xu Date: Tue, 30 Nov 2021 15:42:19 +0800 Subject: [PATCH] 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: Paolo Bonzini Signed-off-by: Like Xu Message-Id: <20211130074221.93635-5-likexu@tencent.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/pmu.c | 58 ++++++++++++++++++++--------------------- 2 files changed, 29 insertions(+), 30 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 344ced0b6b68..ce622b89c5d8 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -495,6 +495,7 @@ struct kvm_pmc { */ u64 current_config; bool is_paused; + bool intr; }; struct kvm_pmu { diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index b7a1ae28ab87..a20207ee4014 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -55,43 +55,41 @@ static void kvm_pmi_trigger_fn(struct irq_work *irq_work) kvm_pmu_deliver_pmi(vcpu); } -static void kvm_perf_overflow(struct perf_event *perf_event, - struct perf_sample_data *data, - struct pt_regs *regs) +static inline void __kvm_perf_overflow(struct kvm_pmc *pmc, bool in_pmi) { - 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); - kvm_make_request(KVM_REQ_PMU, pmc->vcpu); - } + /* Ignore counters that have been reprogrammed already. */ + if (test_and_set_bit(pmc->idx, pmu->reprogram_pmi)) + return; + + __set_bit(pmc->idx, (unsigned long *)&pmu->global_status); + kvm_make_request(KVM_REQ_PMU, pmc->vcpu); + + if (!pmc->intr) + return; + + /* + * 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 + * be sure that vcpu wasn't executing hlt instruction at the + * time of vmexit and is not going to re-enter guest mode until + * woken up. So we should wake it, but this is impossible from + * NMI context. Do it from irq work instead. + */ + if (in_pmi && !kvm_is_in_guest()) + irq_work_queue(&pmc_to_pmu(pmc)->irq_work); + else + kvm_make_request(KVM_REQ_PMI, pmc->vcpu); } -static void kvm_perf_overflow_intr(struct perf_event *perf_event, - struct perf_sample_data *data, - struct pt_regs *regs) +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; - 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); - kvm_make_request(KVM_REQ_PMU, pmc->vcpu); - /* - * 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 - * be sure that vcpu wasn't executing hlt instruction at the - * time of vmexit and is not going to re-enter guest mode until - * woken up. So we should wake it, but this is impossible from - * NMI context. Do it from irq work instead. - */ - if (!kvm_is_in_guest()) - irq_work_queue(&pmc_to_pmu(pmc)->irq_work); - else - kvm_make_request(KVM_REQ_PMI, pmc->vcpu); - } + __kvm_perf_overflow(pmc, true); } 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, - intr ? kvm_perf_overflow_intr : kvm_perf_overflow, pmc); if (IS_ERR(event)) { 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++; clear_bit(pmc->idx, pmc_to_pmu(pmc)->reprogram_pmi); pmc->is_paused = false; + pmc->intr = intr; } static void pmc_pause_counter(struct kvm_pmc *pmc) -- 2.11.0