From: Like Xu <likexu@xxxxxxxxxxx>
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 <likexu@xxxxxxxxxxx>
---
arch/x86/kvm/pmu.c | 3 ++-
arch/x86/kvm/pmu.h | 3 ++-
2 files changed, 4 insertions(+), 2 deletions(-)
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,
--
2.38.1
