linux-kernel - Re: [PATCH v2 1/5] x86/speculation: Provide a debugfs file to dump SPEC

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Date:   Wed, 21 Jun 2023 10:24:42 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Waiman Long <longman@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Len Brown <lenb@...nel.org>, linux-kernel@...r.kernel.org,
        x86@...nel.org, linux-pm@...r.kernel.org,
        Robin Jarry <rjarry@...hat.com>, Joe Mario <jmario@...hat.com>
Subject: Re: [PATCH v2 1/5] x86/speculation: Provide a debugfs file to dump
 SPEC_CTRL MSRs

On Wed, Jun 21, 2023 at 09:41:05AM +0200, Peter Zijlstra wrote:
> On Tue, Jun 20, 2023 at 10:06:21AM -0400, Waiman Long wrote:
> > Sometimes it is useful to know the states the SPEC_CTRL MSRs to see what
> > mitigations are enabled at run time. Provide a new x86/spec_ctrl_msrs
> > debugfs file to dump the cached versions of the current SPEC_CTRL MSRs.
> > 
> 
> Pff, clearly I can't even read email anymore..
> 
> We don't do this for any of the other MSRs, so why start now?

Hell no.

There's /sys/devices/system/cpu/vulnerabilities/ for that.

We are abstracting MSRs away from APIs - not do the backwards thing.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette