Re: [PATCH v2 01/15] perf/x86/lbr: Simplify the exposure check for the LBR_INFO registers

Like Xu
2022-12-22T10:58:06Z

Hi Peter, would you help apply this one in your tip/perf tree,
as it doesn't seem to be closely tied to the KVM changes. Thanks.

On 25/11/2022 12:05 pm, Yang Weijiang wrote:
> From: Like Xu <like.xu@linux.intel.com>
>
> The x86_pmu.lbr_info is 0 unless explicitly initialized, so there's
> no point checking x86_pmu.intel_cap.lbr_format.
>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
> Reviewed-by: Andi Kleen <ak@linux.intel.com>
> Signed-off-by: Like Xu <like.xu@linux.intel.com>
> Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> ---
> arch/x86/events/intel/lbr.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
> index 4dbde69c423b..e7caabfa1377 100644
> --- a/arch/x86/events/intel/lbr.c
> +++ b/arch/x86/events/intel/lbr.c
> @@ -1606,12 +1606,10 @@ void __init intel_pmu_arch_lbr_init(void)
> */
> void x86_perf_get_lbr(struct x86_pmu_lbr *lbr)
> {
> - int lbr_fmt = x86_pmu.intel_cap.lbr_format;
> -
> lbr->nr = x86_pmu.lbr_nr;
> lbr->from = x86_pmu.lbr_from;
> lbr->to = x86_pmu.lbr_to;
> - lbr->info = (lbr_fmt == LBR_FORMAT_INFO) ? x86_pmu.lbr_info : 0;
> + lbr->info = x86_pmu.lbr_info;
> }
> EXPORT_SYMBOL_GPL(x86_perf_get_lbr);
>