On 2023-11-20 8:46 p.m., Dapeng Mi wrote:
> When running perf-stat command on Intel hybrid platform, perf-stat
> reports the following errors.
>
> sudo taskset -c 7 ./perf stat -vvvv -e cpu_atom/instructions/ sleep 1
>
> Opening: cpu/cycles/:HG
> ------------------------------------------------------------
> perf_event_attr:
> type 0 (PERF_TYPE_HARDWARE)
> config 0xa00000000
> disabled 1
> ------------------------------------------------------------
> sys_perf_event_open: pid 0 cpu -1 group_fd -1 flags 0x8
> sys_perf_event_open failed, error -16
>
> Performance counter stats for 'sleep 1':
>
> <not counted> cpu_atom/instructions/
>
> It looks the cpu_atom/instructions/ event can't be enabled on atom pmu
> even the process is pinned on atom core. The investigation shows that
> exclusive_event_init() helper always returns -EBUSY error in the perf
> event creation. That's strange since the atom pmu should not be a
> exclusive PMU.
>
> Further investigation shows the issue is introduced by commit 97588df87b56
> ("perf/x86/intel: Add common intel_pmu_init_hybrid()"). The commit
> originally intents to clear the bit PERF_PMU_CAP_AUX_OUTPUT from pmu
> capabilities if intel_cap.pebs_output_pt_available is not set, but it
> incorrectly uses 'or' operation and leads to all pmu capabilities bits
> are set to 1 except bit PERF_PMU_CAP_AUX_OUTPUT.
>
> Testing this fix on Intel hybrid platforms, the observed issues
> disappear.
>
> Fixes: 97588df87b56 ("perf/x86/intel: Add common intel_pmu_init_hybrid()")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
Reviewed-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Thanks,
Kan
> ---
> arch/x86/events/intel/core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index a08f794a0e79..ce1c777227b4 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -4660,7 +4660,7 @@ static void intel_pmu_check_hybrid_pmus(struct x86_hybrid_pmu *pmu)
> if (pmu->intel_cap.pebs_output_pt_available)
> pmu->pmu.capabilities |= PERF_PMU_CAP_AUX_OUTPUT;
> else
> - pmu->pmu.capabilities |= ~PERF_PMU_CAP_AUX_OUTPUT;
> + pmu->pmu.capabilities &= ~PERF_PMU_CAP_AUX_OUTPUT;
>
> intel_pmu_check_event_constraints(pmu->event_constraints,
> pmu->num_counters,
>
> base-commit: b85ea95d086471afb4ad062012a4d73cd328fa86
