linux-kernel - Re: [PATCH v3] x86/bugs: Add a separate config for each mitigation

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Message-ID: <ZR/om/SzaPCwzYv7@gmail.com>
Date:   Fri, 6 Oct 2023 03:59:39 -0700
From:   Breno Leitao <leitao@...ian.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <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>,
        Josh Poimboeuf <jpoimboe@...nel.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 v3] x86/bugs: Add a separate config for each mitigation

On Fri, Oct 06, 2023 at 11:54:10AM +0200, Borislav Petkov wrote:
> On Thu, Oct 05, 2023 at 11:29:02AM -0700, Linus Torvalds wrote:
> > ...
> > "complex" conditionals may also be annoying, but dammit, they are
> > important documentation about why we do those things, and unlike just
> > comments that will inevitably bit-rot, they have semantics and get
> > tested.
> 
> Thanks for explaining - it does make sense to me.
Thanks for clarifying it.

> So, from the looks of it, we're halfway there:
> 
>  - SPECULATION_MITIGATIONS is there for people who want to whack off the
>    whole crap
> 
>  - the separate Kconfig switches are for people who want to do
>    a finer-grained control. And yeah, they might be annoying the first
>    time but you do them once and then you use the .config forever, like
>    with anything else.
> 
> So yeah, sounds like a plan. Breno, please add Linus' explanation to the
> commit message why we're doing it this way, when sending your new
> version.

Sure, I will update the version 3 of the patchset[1] and add Linus'
explanation plus some new mitigation that showed up in the meantime.

[1] https://lore.kernel.org/all/20230628142129.2468174-1-leitao@debian.org/