From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org
Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.1.y 2/2] perf/x86/intel: Fix GRT PEBS load/store direction for latency events, to fix sample classification
Date: Wed, 30 Sep 2026 12:40:14 -0400
Message-ID: <20260930164014.3227731-2-sashal@kernel.org>
In-Reply-To: <20260930164014.3227731-1-sashal@kernel.org>
References: <2026092920-backward-implant-a0a9@gregkh>
 <20260930164014.3227731-1-sashal@kernel.org>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

From: Dapeng Mi <dapeng1.mi@linux.intel.com>

[ Upstream commit 89dc568e8c0be60e05e5fcd0b528c79077d7b84b ]

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@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org> # v7.2+
Link: https://patch.msgid.link/20260917015234.981153-2-dapeng1.mi@linux.intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 d1cf9876c931d..d05db7aeef78a 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -224,6 +224,7 @@ 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() &&
@@ -238,7 +239,16 @@ 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)
@@ -839,8 +849,8 @@ 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
 };
 
-- 
2.53.0