linux-kernel - Re: [PATCH] x86/microcode/AMD: Attempt applying on every logical thread

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Message-ID: <YvuQgx698T5cgF+C@zn.tnic>
Date:   Tue, 16 Aug 2022 14:41:39 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ashok Raj <ashok_raj@...ux.intel.com>
Cc:     X86 ML <x86@...nel.org>, Andrew Cooper <amc96@...f.net>,
        LKML <linux-kernel@...r.kernel.org>,
        Ștefan Talpalaru <stefantalpalaru@...oo.com>,
        Ashok Raj <ashok.raj@...el.com>
Subject: Re: [PATCH] x86/microcode/AMD: Attempt applying on every logical
 thread

On Tue, Aug 16, 2022 at 09:00:14AM +0000, Ashok Raj wrote:
> A re-application means, you want to apply even if the cpu_rev <= patch.rev

Yes.

> if cpu_rev is > patch_rev, clearly its ahead?. say BIOS has a newer
> version than in the initrd image, do we want to replace the BIOS
> version since we do no revid checks here.

Can you even downgrade the microcode through the MSR?

-- 
Regards/Gruss,
    Boris.

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