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Message-ID: <2cdb371d-7435-ff4f-c9c0-991371833ad1@redhat.com>
Date:   Wed, 21 Jun 2023 10:02:02 -0400
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Subject: Re: [PATCH v2 1/5] x86/speculation: Provide a debugfs file to dump
 SPEC_CTRL MSRs
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To:     Borislav Petkov <bp@alien8.de>,
        Peter Zijlstra <peterz@infradead.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Len Brown <lenb@kernel.org>, linux-kernel@vger.kernel.org,
        x86@kernel.org, linux-pm@vger.kernel.org,
        Robin Jarry <rjarry@redhat.com>, Joe Mario <jmario@redhat.com>
References: <20230620140625.1001886-1-longman@redhat.com>
 <20230620140625.1001886-2-longman@redhat.com>
 <20230621074105.GE2046280@hirez.programming.kicks-ass.net>
 <20230621082442.GCZJKzyjqRPMAnsWKZ@fat_crate.local>
From:   Waiman Long <longman@redhat.com>
In-Reply-To: <20230621082442.GCZJKzyjqRPMAnsWKZ@fat_crate.local>
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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