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 10:02:02 -0400
From:   Waiman Long <longman@...hat.com>
To:     Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     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 6/21/23 04:24, Borislav Petkov wrote:
> 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.
>
OK, as I have said. This is not central to the main purpose of this 
patch series. It is mostly there for verification purpose. I can 
certainly take this out.

Cheers,
Longman