Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 21 Jun 2023 10:24:42 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Waiman Long <longman@redhat.com>,
        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>
Subject: Re: [PATCH v2 1/5] x86/speculation: Provide a debugfs file to dump
 SPEC_CTRL MSRs
Message-ID: <20230621082442.GCZJKzyjqRPMAnsWKZ@fat_crate.local>
References: <20230620140625.1001886-1-longman@redhat.com>
 <20230620140625.1001886-2-longman@redhat.com>
 <20230621074105.GE2046280@hirez.programming.kicks-ass.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20230621074105.GE2046280@hirez.programming.kicks-ass.net>
Precedence: bulk

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