linux-kernel - Re: [patch V3 08/30] x86/microcode/intel: Save the microcode only after a successful late-load

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Message-ID: <20230920143928.GFZQsEIFvAuH8YMSq6@fat_crate.local>
Date:   Wed, 20 Sep 2023 16:39:28 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        "Chang S. Bae" <chang.seok.bae@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Nikolay Borisov <nik.borisov@...e.com>
Subject: Re: [patch V3 08/30] x86/microcode/intel: Save the microcode only
 after a successful late-load

On Tue, Sep 12, 2023 at 09:57:56AM +0200, Thomas Gleixner wrote:
> From: Thomas Gleixner <tglx@...utronix.de>
> 
> There are situations where the late microcode is loaded into memory, but is
> not applied:
> 
>   1) The rendevouz fails
>   2) The microcode is rejected by the CPUs
> 
> If any of this happens then the pointer which was updated at firmware load
> time is stale and subsequent CPU hotplug operations either fail to update
> or create inconsistent microcode state.
> 
> Save the loaded microcode in a separate pointer from with the late load is

s/from with/before/

> attempted and when successful, update the hotplug pointer accordingly via a
> new micrcode_ops callback.

-- 
Regards/Gruss,
    Boris.

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