linux-kernel - Re: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge

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Message-ID: <1339163771.2507.18.camel@laptop>
Date:	Fri, 08 Jun 2012 15:56:11 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Borislav Petkov <borislav.petkov@....com>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Stephane Eranian <eranian@...gle.com>,
	linux-kernel@...r.kernel.org, andi@...stfloor.org, mingo@...e.hu,
	ming.m.lin@...el.com, Andreas Herrmann <andreas.herrmann3@....com>,
	Dimitri Sivanich <sivanich@....com>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>
Subject: Re: [PATCH] perf/x86: check ucode before disabling PEBS on
 SandyBridge

On Fri, 2012-06-08 at 15:51 +0200, Borislav Petkov wrote:
> 
> In these cases, you already have PEBS fixed but since you're not loading
> any ucode, you won't run intel_snb_verify_ucode().
> 
> So, you want to check for PEBS twice (and for all other features fixed
> by ucode and tested for earlier than the ucode loader, for that matter):
> 
> * once when perf inits
> 
> * twice, a bit later when the ucode loader has loaded something from
> userspace and the notifier corrects it. 


>  static __init void intel_sandybridge_quirk(void)
>  {
> +       intel_snb_verify_ucode();
> +       /*
> +        * we're still single threaded, so while there's a hole here,
> +        * you can't trigger it.
> +        */
> +       microcode_notifier(intel_snb_ucode_notifier);
>  }

Like that you mean?

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