linux-kernel - Re: [PATCH RFC 1/3] x86: microcode: intel: read microcode metadata file

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Message-ID: <20200504141211.GG15046@zn.tnic>
Date:   Mon, 4 May 2020 16:12:11 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Mihai Carabas <mihai.carabas@...cle.com>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, Jonathan Corbet <corbet@....net>,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH RFC 1/3] x86: microcode: intel: read microcode metadata
 file

> Subject: Re: [PATCH RFC 1/3] x86: microcode: intel: read microcode metadata file

For the future, do:

git log <file I'm changing under arch/x86/>

to figure out what commit title prefix to use for the tip tree.

On Mon, Apr 27, 2020 at 10:27:57AM +0300, Mihai Carabas wrote:
> Try to read the microcode metadata file in order to see what features
> are added or remove by the new microcode blob. If the metadata file
> does not exists passthrough normal loading with a warning message.

So this file must be signed by the microcode vendors and that signature
then must be verified by the loader before we even look at the metadata.
We don't trust luserspace.

Also, I don't like it being a separate file - it could just as well be
appended to the microcode blob and parsed properly by the loader.

Thx.

-- 
Regards/Gruss,
    Boris.

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