From 55c590adfe18b5380f7c4ae3696468bc5c916ee5 Mon Sep 17 00:00:00 2001 From: Like Xu Date: Wed, 7 Dec 2022 15:15:05 +0800 Subject: KVM: x86/pmu: Prevent zero period event from being repeatedly released The current vPMU can reuse the same pmc->perf_event for the same hardware event via pmc_pause/resume_counter(), but this optimization does not apply to a portion of the TSX events (e.g., "event=0x3c,in_tx=1, in_tx_cp=1"), where event->attr.sample_period is legally zero at creation, thus making the perf call to perf_event_period() meaningless (no need to adjust sample period in this case), and instead causing such reusable perf_events to be repeatedly released and created. Avoid releasing zero sample_period events by checking is_sampling_event() to follow the previously enable/disable optimization. Signed-off-by: Like Xu Message-Id: <20221207071506.15733-2-likexu@tencent.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/pmu.c | 3 ++- arch/x86/kvm/pmu.h | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 684393c22105..eb594620dd75 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -238,7 +238,8 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc) return false; /* recalibrate sample period and check if it's accepted by perf core */ - if (perf_event_period(pmc->perf_event, + if (is_sampling_event(pmc->perf_event) && + perf_event_period(pmc->perf_event, get_sample_period(pmc, pmc->counter))) return false; diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h index 85ff3c0588ba..cdb91009701d 100644 --- a/arch/x86/kvm/pmu.h +++ b/arch/x86/kvm/pmu.h @@ -140,7 +140,8 @@ static inline u64 get_sample_period(struct kvm_pmc *pmc, u64 counter_value) static inline void pmc_update_sample_period(struct kvm_pmc *pmc) { - if (!pmc->perf_event || pmc->is_paused) + if (!pmc->perf_event || pmc->is_paused || + !is_sampling_event(pmc->perf_event)) return; perf_event_period(pmc->perf_event, -- cgit v1.2.3