linux-kernel - Re: [RFC PATCH 3/3] x86/microcode: Taint and warn on late loading

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Message-ID: <Yo3cpb1yZhwhHEga@zn.tnic>
Date:   Wed, 25 May 2022 09:37:09 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "Luck, Tony" <tony.luck@...el.com>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 3/3] x86/microcode: Taint and warn on late loading

On Wed, May 25, 2022 at 08:59:40AM +0200, Peter Zijlstra wrote:
> On Tue, May 24, 2022 at 06:03:04PM -0700, Luck, Tony wrote:
> > On Tue, May 24, 2022 at 08:53:24PM +0200, Borislav Petkov wrote:
> > > +	add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
> > 
> > Seems harsh. Updating microcode to the latest is arguably the
> > way to make sure that your CPU stays "IN_SPEC" (since the microcode
> > may have a fix for a functional issue).
> 
> Then use early loading. There's too many fails associated with late
> loading.

Yes, short of

TAINT_YOU_DID_SOMETHING_DANGEROUS

we simply don't have a better taint flag.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette