linux-kernel - Re: [PATCH] x86/microcode: Be more verbose, especially about loading errors

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Message-ID: <CAG48ez3weAU-Uti0QyBSDNRv8xYqCJ5UbgJvssEWAWpvyon0DA@mail.gmail.com>
Date:   Wed, 6 Dec 2023 21:23:48 +0100
From:   Jann Horn <jannh@...gle.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     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>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/microcode: Be more verbose, especially about loading errors

On Wed, Dec 6, 2023 at 8:58 PM Borislav Petkov <bp@...en8.de> wrote:
> On Wed, Dec 06, 2023 at 06:28:44PM +0100, Jann Horn wrote:
> > The AMD ucode loader contains several checks for corrupted ucode blobs that
> > only log with pr_debug(); make them pr_err(), corrupted ucode blobs are
> > bad.
> >
> > Also make both microcode loaders a bit more verbose about whether they
> > found ucode blobs at all and whether they found ucode for the specific CPU.
>
> So far, so good.
>
> The only thing I'm missing here is the *why*.
>
> There's merit in not complaining about corrupted microcode blobs because
> they won't be loaded anyway: no harm, no foul.

Well, yes, except that if no microcode blob is loaded, you're not
gonna have the errata fixes and/or security mitigations that you might
expect to have.