linux-kernel - Re: [tip:perf/urgent] perf/x86/intel: Initialize TFA MSR

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Date:   Wed, 3 Apr 2019 13:30:47 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     nelson.dsouza@...el.com, jolsa@...hat.com,
        linux-kernel@...r.kernel.org, alexander.shishkin@...ux.intel.com,
        peterz@...radead.org, vincent.weaver@...ne.edu, eranian@...gle.com,
        hpa@...or.com, mingo@...nel.org, torvalds@...ux-foundation.org,
        acme@...hat.com
cc:     linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/urgent] perf/x86/intel: Initialize TFA MSR

On Wed, 3 Apr 2019, tip-bot for Peter Zijlstra wrote:

> Commit-ID:  d7262457e35dbe239659e62654e56f8ddb814bed
> Gitweb:     https://git.kernel.org/tip/d7262457e35dbe239659e62654e56f8ddb814bed
> Author:     Peter Zijlstra <peterz@...radead.org>
> AuthorDate: Thu, 21 Mar 2019 13:38:49 +0100
> Committer:  Ingo Molnar <mingo@...nel.org>
> CommitDate: Wed, 3 Apr 2019 11:40:32 +0200
> 
> perf/x86/intel: Initialize TFA MSR
> 
> Stephane reported that the TFA MSR is not initialized by the kernel,
> but the TFA bit could set by firmware or as a leftover from a kexec,
> which makes the state inconsistent.
> 
> Reported-by: Stephane Eranian <eranian@...gle.com>
> Tested-by: Nelson DSouza <nelson.dsouza@...el.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Jiri Olsa <jolsa@...hat.com>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Vince Weaver <vincent.weaver@...ne.edu>
> Cc: tonyj@...e.com
> Link: https://lkml.kernel.org/r/20190321123849.GN6521@hirez.programming.kicks-ass.net
> Signed-off-by: Ingo Molnar <mingo@...nel.org>

This lacks:

 1) Fixes tag

 2) Cc: stable ....

Sigh.

> ---
>  arch/x86/events/intel/core.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> index 1539647ea39d..f61dcbef20ff 100644
> --- a/arch/x86/events/intel/core.c
> +++ b/arch/x86/events/intel/core.c
> @@ -3575,6 +3575,12 @@ static void intel_pmu_cpu_starting(int cpu)
>  
>  	cpuc->lbr_sel = NULL;
>  
> +	if (x86_pmu.flags & PMU_FL_TFA) {
> +		WARN_ON_ONCE(cpuc->tfa_shadow);
> +		cpuc->tfa_shadow = ~0ULL;
> +		intel_set_tfa(cpuc, false);
> +	}
> +
>  	if (x86_pmu.version > 1)
>  		flip_smm_bit(&x86_pmu.attr_freeze_on_smi);
>  
>