From: Kan Liang kan.liang@linux.intel.com
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@linux.intel.com Signed-off-by: Kan Liang kan.liang@linux.intel.com Cc: stable@vger.kernel.org ---
The original post can be found at https://lkml.kernel.org/r/1623413662-18373-1-git-send-email-kan.liang@linux....
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 2521d03..d39991b 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,