linux-kernel - Re: [PATCH 1/2] amd: uncore: Rename cpufeatures macro for cache counters

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Date:   Tue, 6 Jun 2017 18:31:41 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Janakarajan Natarajan <Janakarajan.Natarajan@....com>
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Subject: Re: [PATCH 1/2] amd: uncore: Rename cpufeatures macro for cache
 counters

On Mon, Jun 05, 2017 at 11:13:18AM -0500, Janakarajan Natarajan wrote:
> In Family 17h, L3 is the last level cache as opposed to L2 in previous
> families. Avoid this name confusion and rename X86_FEATURE_PERFCT_L2 to
> X86_FEATURE_PERFCTR_LLC to indicate the performance counter on the last
> level of cache.
> 
> Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@....com>
> ---
>  arch/x86/events/amd/uncore.c       | 2 +-
>  arch/x86/include/asm/cpufeatures.h | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
> index 4d1f7f2d..8fea711 100644
> --- a/arch/x86/events/amd/uncore.c
> +++ b/arch/x86/events/amd/uncore.c
> @@ -569,7 +569,7 @@ static int __init amd_uncore_init(void)
>  		ret = 0;
>  	}
>  
> -	if (boot_cpu_has(X86_FEATURE_PERFCTR_L2)) {
> +	if (boot_cpu_has(X86_FEATURE_PERFCTR_LLC)) {
>  		amd_uncore_llc = alloc_percpu(struct amd_uncore *);
>  		if (!amd_uncore_llc) {
>  			ret = -ENOMEM;
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index b04bb6d..da422d6 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -177,7 +177,7 @@
>  #define X86_FEATURE_PERFCTR_NB  ( 6*32+24) /* NB performance counter extensions */
>  #define X86_FEATURE_BPEXT	(6*32+26) /* data breakpoint extension */
>  #define X86_FEATURE_PTSC	( 6*32+27) /* performance time-stamp counter */
> -#define X86_FEATURE_PERFCTR_L2	( 6*32+28) /* L2 performance counter extensions */
> +#define X86_FEATURE_PERFCTR_LLC	( 6*32+28) /* Last Level Cache performance counter extensions */

Bah, the Zen PPR calls this PerfCtrExtL3 now. And F16h BKDG calls it
PerfCtrExtL2I.

Can this be fixed to be PerfCtrExtLLC in the docs so that there is no
more confusion?

-- 
Regards/Gruss,
    Boris.

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