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From: Dapeng Mi <dapeng1.mi@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Eranian Stephane <eranian@google.com>
Cc: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
	Dapeng Mi <dapeng1.mi@intel.com>, Zide Chen <zide.chen@intel.com>,
	Falcon Thomas <thomas.falcon@intel.com>,
	Xudong Hao <xudong.hao@intel.com>,
	Dapeng Mi <dapeng1.mi@linux.intel.com>,
	Yi Lai <yi1.lai@intel.com>
Subject: [Patch v2 7/9] perf/x86/intel: Drop fixed-counter PEBS constraints for baseline PEBS
Date: Tue,  9 Jun 2026 13:02:20 +0800	[thread overview]
Message-ID: <20260609050222.2458129-8-dapeng1.mi@linux.intel.com> (raw)
In-Reply-To: <20260609050222.2458129-1-dapeng1.mi@linux.intel.com>

On SPR guests where pebs_baseline is not advertised, running:

$ ./perf record -e cpu/event=0x00,umask=0x01,i\
	 name=INST_RETIRED.PREC_DIST/p -c 10000 sleep 1

can trigger:

unchecked MSR access error: WRMSR to 0x3f1 ... in\
	 intel_pmu_pebs_enable_all()

Root cause:
SPR-specific PEBS constraints allow fixed-counter scheduling,
for example INST_RETIRED.PREC_DIST on fixed counter 0. In guests without
pebs_baseline, KVM does not support PEBS sampling on fixed counters,
so enabling such events reaches an invalid MSR programming path.

Fix:
Drop fixed-counter entries from the PEBS constraint table. Without
pebs_baseline, those fixed-counter PEBS events now resolve to empty
constraints and are not scheduled/enabled, avoiding the warning and the
broken guest PEBS path.

This is safe because, in pebs_baseline-capable cases, PEBS constraint
lookup already falls back to non-PEBS constraints when needed, and
fixed-counter constraints are effectively shared there.

Reported-by: Yi Lai <yi1.lai@intel.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---
 arch/x86/events/intel/ds.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index cb72af9b61ce..5db15a92017a 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1447,10 +1447,6 @@ struct event_constraint intel_skl_pebs_event_constraints[] = {
 };
 
 struct event_constraint intel_icl_pebs_event_constraints[] = {
-	INTEL_FLAGS_UEVENT_CONSTRAINT(0x01c0, 0x100000000ULL),	/* old INST_RETIRED.PREC_DIST */
-	INTEL_FLAGS_UEVENT_CONSTRAINT(0x0100, 0x100000000ULL),	/* INST_RETIRED.PREC_DIST */
-	INTEL_FLAGS_UEVENT_CONSTRAINT(0x0400, 0x800000000ULL),	/* SLOTS */
-
 	INTEL_PLD_CONSTRAINT(0x1cd, 0xff),			/* MEM_TRANS_RETIRED.LOAD_LATENCY */
 	INTEL_FLAGS_UEVENT_CONSTRAINT_DATALA_LD(0x11d0, 0xf),	/* MEM_INST_RETIRED.STLB_MISS_LOADS */
 	INTEL_FLAGS_UEVENT_CONSTRAINT_DATALA_ST(0x12d0, 0xf),	/* MEM_INST_RETIRED.STLB_MISS_STORES */
@@ -1473,9 +1469,6 @@ struct event_constraint intel_icl_pebs_event_constraints[] = {
 };
 
 struct event_constraint intel_glc_pebs_event_constraints[] = {
-	INTEL_FLAGS_UEVENT_CONSTRAINT(0x100, 0x100000000ULL),	/* INST_RETIRED.PREC_DIST */
-	INTEL_FLAGS_UEVENT_CONSTRAINT(0x0400, 0x800000000ULL),
-
 	INTEL_FLAGS_EVENT_CONSTRAINT(0xc0, 0xfe),
 	INTEL_PLD_CONSTRAINT(0x1cd, 0xfe),
 	INTEL_PSD_CONSTRAINT(0x2cd, 0x1),
@@ -1500,9 +1493,6 @@ struct event_constraint intel_glc_pebs_event_constraints[] = {
 };
 
 struct event_constraint intel_lnc_pebs_event_constraints[] = {
-	INTEL_FLAGS_UEVENT_CONSTRAINT(0x100, 0x100000000ULL),	/* INST_RETIRED.PREC_DIST */
-	INTEL_FLAGS_UEVENT_CONSTRAINT(0x0400, 0x800000000ULL),
-
 	INTEL_FLAGS_UEVENT_CONSTRAINT(0x012a, 0x1),		/* OCR.* events */
 	INTEL_FLAGS_UEVENT_CONSTRAINT(0x012b, 0x1),		/* OCR.* events */
 
@@ -1534,9 +1524,6 @@ struct event_constraint intel_lnc_pebs_event_constraints[] = {
 };
 
 struct event_constraint intel_pnc_pebs_event_constraints[] = {
-	INTEL_FLAGS_UEVENT_CONSTRAINT(0x100, 0x100000000ULL),	/* INST_RETIRED.PREC_DIST */
-	INTEL_FLAGS_UEVENT_CONSTRAINT(0x0400, 0x800000000ULL),
-
 	INTEL_HYBRID_LDLAT_CONSTRAINT(0x1cd, 0xfc),
 	INTEL_HYBRID_STLAT_CONSTRAINT(0x2cd, 0x3),
 	INTEL_FLAGS_UEVENT_CONSTRAINT_DATALA_LD(0x11d0, 0xf),	/* MEM_INST_RETIRED.STLB_MISS_LOADS */
-- 
2.34.1


  parent reply	other threads:[~2026-06-09  5:08 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-09  5:02 [Patch v2 0/9] perf/x86: Miscellaneous PMU bug fixes Dapeng Mi
2026-06-09  5:02 ` [Patch v2 1/9] perf/x86/intel: Remove anythread_deprecated bit from perf_capabilities Dapeng Mi
2026-06-09  5:02 ` [Patch v2 2/9] perf/x86: Introduce is_x86_pmu() helper Dapeng Mi
2026-06-09  5:02 ` [Patch v2 3/9] perf/x86: Update cap_user_rdpmc base on rdpmc user disable state Dapeng Mi
2026-06-09  5:02 ` [Patch v2 4/9] perf/x86/intel: Fallback to sw branch type decoding if no hw decoding Dapeng Mi
2026-06-09  5:24   ` sashiko-bot
2026-06-09  5:02 ` [Patch v2 5/9] perf/x86/intel: Drop LBR entries whose privilege level mismatches br_sel Dapeng Mi
2026-06-09  5:21   ` sashiko-bot
2026-06-09  5:02 ` [Patch v2 6/9] perf/x86/intel: Validate return value of intel_pmu_init_hybrid() Dapeng Mi
2026-06-09  5:25   ` sashiko-bot
2026-06-09  5:02 ` Dapeng Mi [this message]
2026-06-09  5:02 ` [Patch v2 8/9] perf/core: Fix kernel register info leak via hardware skid Dapeng Mi
2026-06-09  5:02 ` [Patch v2 9/9] perf/core: Check kernel access when kernel callchains are requested Dapeng Mi
2026-06-09  5:24   ` sashiko-bot

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