[PATCH 01/12] perf/x86/intel: Fix GRT PEBS load/store direction for latency events

From: Dapeng Mi

Date: Wed Sep 16 2026 - 22:00:27 EST


On Gracemont, intel_grt_pebs_event_constraints[] applies LAT_CONSTRAINT
constraints to MEM_UOPS_RETIRED.{LOAD,STORE}_LATENCY, but does not set
explicit LOAD/STORE flags for those events.

The PEBS latency path (pebs_latency_data(), via __grt_latency_data())
uses the event flags to determine memory operation direction. Without an
explicit STORE flag, samples from MEM_UOPS_RETIRED.STORE_LATENCY can be
misclassified as LOADs.

Set explicit LOAD/STORE flags in intel_grt_pebs_event_constraints[] for:
- MEM_UOPS_RETIRED.LOAD_LATENCY
- MEM_UOPS_RETIRED.STORE_LATENCY

Also update __grt_latency_data() to explicitly interpret these flags when
assigning the sampled memory operation direction.

This fixes incorrect STORE sample classification.

Fixes: 39a41278f041 ("perf/x86/intel: Fix PEBS memory access info encoding for ADL")
Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
---
arch/x86/events/intel/ds.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 2edff9754eb2..20674871c6c3 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -455,6 +455,7 @@ static inline void pebs_set_tlb_lock(u64 *val, bool tlb, bool lock)
static u64 __grt_latency_data(struct perf_event *event, u64 status,
u8 dse, bool tlb, bool lock, bool blk)
{
+ union perf_mem_data_src src;
u64 val;

WARN_ON_ONCE(is_hybrid() &&
@@ -470,7 +471,16 @@ static u64 __grt_latency_data(struct perf_event *event, u64 status,
else
val |= P(BLK, NA);

- return val;
+ src.val = val;
+
+ if (event->hw.flags &
+ (PERF_X86_EVENT_PEBS_LDLAT | PERF_X86_EVENT_PEBS_LD_HSW))
+ src.mem_op = P(OP, LOAD);
+ if (event->hw.flags &
+ (PERF_X86_EVENT_PEBS_STLAT | PERF_X86_EVENT_PEBS_ST_HSW))
+ src.mem_op = P(OP, STORE);
+
+ return src.val;
}

u64 grt_latency_data(struct perf_event *event, u64 status)
@@ -1288,8 +1298,8 @@ struct event_constraint intel_glm_pebs_event_constraints[] = {

struct event_constraint intel_grt_pebs_event_constraints[] = {
/* Allow all events as PEBS with no flags */
- INTEL_HYBRID_LAT_CONSTRAINT(0x5d0, 0x3),
- INTEL_HYBRID_LAT_CONSTRAINT(0x6d0, 0x3f),
+ INTEL_HYBRID_LDLAT_CONSTRAINT(0x5d0, 0x3),
+ INTEL_HYBRID_STLAT_CONSTRAINT(0x6d0, 0x3f),
EVENT_CONSTRAINT_END
};

--
2.34.1