[Patch v9 10/12] perf/x86/intel: Update dyn_constranit base on PEBS event precise level

From: Dapeng Mi

Date: Wed Oct 29 2025 - 06:25:01 EST


arch-PEBS provides CPUIDs to enumerate which counters support PEBS
sampling and precise distribution PEBS sampling. Thus PEBS constraints
should be dynamically configured base on these counter and precise
distribution bitmap instead of defining them statically.

Update event dyn_constraint base on PEBS event precise level.

Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
---
arch/x86/events/intel/core.c | 11 +++++++++++
arch/x86/events/intel/ds.c | 1 +
2 files changed, 12 insertions(+)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 6e04d73dfae5..40ccfd80d554 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4252,6 +4252,8 @@ static int intel_pmu_hw_config(struct perf_event *event)
}

if (event->attr.precise_ip) {
+ struct arch_pebs_cap pebs_cap = hybrid(event->pmu, arch_pebs_cap);
+
if ((event->attr.config & INTEL_ARCH_EVENT_MASK) == INTEL_FIXED_VLBR_EVENT)
return -EINVAL;

@@ -4265,6 +4267,15 @@ static int intel_pmu_hw_config(struct perf_event *event)
}
if (x86_pmu.pebs_aliases)
x86_pmu.pebs_aliases(event);
+
+ if (x86_pmu.arch_pebs) {
+ u64 cntr_mask = hybrid(event->pmu, intel_ctrl) &
+ ~GLOBAL_CTRL_EN_PERF_METRICS;
+ u64 pebs_mask = event->attr.precise_ip >= 3 ?
+ pebs_cap.pdists : pebs_cap.counters;
+ if (cntr_mask != pebs_mask)
+ event->hw.dyn_constraint &= pebs_mask;
+ }
}

if (needs_branch_stack(event)) {
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 5c26a5235f94..1179980f795b 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -3005,6 +3005,7 @@ static void __init intel_arch_pebs_init(void)
x86_pmu.pebs_buffer_size = PEBS_BUFFER_SIZE;
x86_pmu.drain_pebs = intel_pmu_drain_arch_pebs;
x86_pmu.pebs_capable = ~0ULL;
+ x86_pmu.flags |= PMU_FL_PEBS_ALL;

x86_pmu.pebs_enable = __intel_pmu_pebs_enable;
x86_pmu.pebs_disable = __intel_pmu_pebs_disable;
--
2.34.1