[PATCH 1/3][SRU][U/OEM-5.13] perf/x86/intel: Fix fixed counter check warning for some Alder Lake

You-Sheng Yang vicamo.yang at canonical.com
Tue Jul 13 04:36:53 UTC 2021


From: Kan Liang <kan.liang at linux.intel.com>

BugLink: https://bugs.launchpad.net/bugs/1933617

For some Alder Lake machine, the below fixed counter check warning may be
triggered.

[    2.010766] hw perf events fixed 5 > max(4), clipping!

Current perf unconditionally increases the number of the GP counters and
the fixed counters for a big core PMU on an Alder Lake system, because
the number enumerated in the CPUID only reflects the common counters.
The big core may has more counters. However, Alder Lake may have an
alternative configuration. With that configuration,
the X86_FEATURE_HYBRID_CPU is not set. The number of the GP counters and
fixed counters enumerated in the CPUID is accurate. Perf mistakenly
increases the number of counters. The warning is triggered.

Directly use the enumerated value on the system with the alternative
configuration.

Fixes: f83d2f91d259 ("perf/x86/intel: Add Alder Lake Hybrid support")
Reported-by: Jin Yao <yao.jin at linux.intel.com>
Signed-off-by: Kan Liang <kan.liang at linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
Cc: stable at vger.kernel.org
Link: https://lore.kernel.org/r/1624029174-122219-2-git-send-email-kan.liang@linux.intel.com
(cherry picked from commit ee72a94ea4a6d8fa304a506859cd07ecdc0cf5c4)
Signed-off-by: You-Sheng Yang <vicamo.yang at canonical.com>
---
 arch/x86/events/intel/core.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index e28892270c58..83c8dba7b4b8 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -6157,8 +6157,13 @@ __init int intel_pmu_init(void)
 		pmu = &x86_pmu.hybrid_pmu[X86_HYBRID_PMU_CORE_IDX];
 		pmu->name = "cpu_core";
 		pmu->cpu_type = hybrid_big;
-		pmu->num_counters = x86_pmu.num_counters + 2;
-		pmu->num_counters_fixed = x86_pmu.num_counters_fixed + 1;
+		if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU)) {
+			pmu->num_counters = x86_pmu.num_counters + 2;
+			pmu->num_counters_fixed = x86_pmu.num_counters_fixed + 1;
+		} else {
+			pmu->num_counters = x86_pmu.num_counters;
+			pmu->num_counters_fixed = x86_pmu.num_counters_fixed;
+		}
 		pmu->max_pebs_events = min_t(unsigned, MAX_PEBS_EVENTS, pmu->num_counters);
 		pmu->unconstrained = (struct event_constraint)
 					__EVENT_CONSTRAINT(0, (1ULL << pmu->num_counters) - 1,
-- 
2.31.1




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