linux-kernel - Re: [PATCH v4] x86/bugs: Add a separate config for each mitigation

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Message-ID: <20231011220325.5uje4xnfxuccumm7@treble>
Date:   Wed, 11 Oct 2023 15:03:25 -0700
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Breno Leitao <leitao@...ian.org>, tglx@...utronix.de,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, leit@...a.com,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] x86/bugs: Add a separate config for each mitigation

On Wed, Oct 11, 2023 at 09:03:17PM +0200, Borislav Petkov wrote:
> On Tue, Oct 10, 2023 at 09:42:52PM -0700, Josh Poimboeuf wrote:
> >   MITIGATION_PAGE_TABLE_ISOLATION
> >   MITIGATION_RETPOLINE
> >   MITIGATION_UNRET_ENTRY
> >   MITIGATION_CALL_DEPTH_TRACKING
> >   MITIGATION_IBPB_ENTRY
> >   MITIGATION_IBRS_ENTRY
> >   MITIGATION_SRSO
> >   MITIGATION_SLS
> 
> The train has already left the station on those. The other mitigations
> don't have "MITIGAT*" at all in front of the name. I.e.:
> 
> config RETHUNK
> config CALL_DEPTH_TRACKING
> ...
> 
> and prepending them all with MITIGATION_ is going to cause too much
> senseless churn for a reason which I don't think is worth the effort.

I wouldn't call it senseless churn.  There are concrete benefits -- for
both users and developers -- of having all the mitigation config options
living in the same config namespace.

Sure, the change might cause pain for users who disable these options,
but do those users actually exist?

-- 
Josh