linux-kernel - Re: [PATCH v6 3/8] x86/microcode/AMD: Check microcode container data in the early loader

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Message-ID: <20180615114253.GD25559@zn.tnic>
Date:   Fri, 15 Jun 2018 13:42:54 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 3/8] x86/microcode/AMD: Check microcode container data
 in the early loader

On Thu, Jun 14, 2018 at 10:56:07PM +0200, Maciej S. Szmigiero wrote:
> At this point we don't know the CPU family the particular patch is for
> since the patch header contains only CPU rev_id, not an explicit family
> number.

	patch_fam = 0xf + (mc->processor_rev_id >> 12);

which means, you can do

        if (patch_fam != family)
                return 0;

like verify_and_add_patch() does before calling verify_patch() with the
correct family of the current CPU.

-- 
Regards/Gruss,
    Boris.

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