Re: [PATCH 3/7] perf/x86/intel/uncore: Keep PCI PMUs working when MMIO/MSR setup fails

[Ian Rogers]

On Tue, May 12, 2026 at 4:39 PM Zide Chen <zide.chen@xxxxxxxxx> wrote:
>
> uncore_event_cpu_online() returns -ENOMEM early when both the MSR and
> MMIO box allocations fail.  This also aborts PCI uncore setup, even
> though PCI PMUs are independent of the MSR/MMIO paths.
>
> Remove the early return so PCI uncore setup always runs regardless
> of whether MSR or MMIO box allocation succeeds.
>
> Fixes: 3da04b8a00dd ("perf/x86/intel/uncore: Support MMIO type uncore blocks")
> Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  arch/x86/events/intel/uncore.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
> index 012a7e081014..8d5170788af2 100644
> --- a/arch/x86/events/intel/uncore.c
> +++ b/arch/x86/events/intel/uncore.c
> @@ -1632,8 +1632,6 @@ static int uncore_event_cpu_online(unsigned int cpu)
>         die = topology_logical_die_id(cpu);
>         msr_ret = uncore_box_ref(uncore_msr_uncores, die, cpu);
>         mmio_ret = uncore_box_ref(uncore_mmio_uncores, die, cpu);
> -       if (msr_ret && mmio_ret)
> -               return -ENOMEM;
>
>         /*
>          * Check if there is an online cpu in the package
> --
> 2.54.0
>