linux-kernel - Re: [tip: x86/urgent] x86/microcode: Consolidate the loader enablement checking

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Message-ID: <aBcFv6BzmRNWqLY8@gmail.com>
Date: Sun, 4 May 2025 08:14:23 +0200
From: Ingo Molnar <mingo@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: linux-tip-commits@...r.kernel.org,
	"Borislav Petkov (AMD)" <bp@...en8.de>, stable@...nel.org,
	x86@...nel.org
Subject: Re: [tip: x86/urgent] x86/microcode: Consolidate the loader
 enablement checking


* tip-bot2 for Borislav Petkov (AMD) <tip-bot2@...utronix.de> wrote:

> The following commit has been merged into the x86/urgent branch of tip:
> 
> Commit-ID:     eb72bdfbd0a757f30ebe4f9ec161cb246d19e5ed
> Gitweb:        https://git.kernel.org/tip/eb72bdfbd0a757f30ebe4f9ec161cb246d19e5ed
> Author:        Borislav Petkov (AMD) <bp@...en8.de>
> AuthorDate:    Mon, 14 Apr 2025 11:59:33 +02:00
> Committer:     Borislav Petkov (AMD) <bp@...en8.de>
> CommitterDate: Sat, 03 May 2025 16:40:56 +02:00
> 
> x86/microcode: Consolidate the loader enablement checking
> 
> Consolidate the whole logic which determines whether the microcode loader
> should be enabled or not into a single function and call it everywhere.
> 
> Well, almost everywhere - not in mk_early_pgtbl_32() because there the kernel
> is running without paging enabled and checking dis_ucode_ldr et al would
> require physical addresses and uglification of the code.
> 
> But since this is 32-bit, the easier thing to do is to simply map the initrd
> unconditionally especially since that mapping is getting removed later anyway
> by zap_early_initrd_mapping() and avoid the uglification.
> 
> Fixes: 4c585af7180c1 ("x86/boot/32: Temporarily map initrd for microcode loading")
> Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
> Cc: <stable@...nel.org>
> Link: https://lore.kernel.org/r/CANpbe9Wm3z8fy9HbgS8cuhoj0TREYEEkBipDuhgkWFvqX0UoVQ@mail.gmail.com

So the title claims this 'consolidates' microcode loader enablement, 
which is basically a code refactoring, but then there's a Fixes tag - 
what exactly does it fix? There's no explanation in the changelog that 
I can see that justifies that tag and why it's in x86/urgent.

Thanks,

	Ingo