linux-kernel - Re: [PATCH] x86, microcode, AMD: Fix patch level reporting for family15h

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Message-ID: <20130926221322.GC10123@pd.tnic>
Date:	Fri, 27 Sep 2013 00:13:22 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	suravee.suthikulpanit@....com
Cc:	herrmann.der.user@...glemail.com, jacob.w.shin@...il.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86, microcode, AMD: Fix patch level reporting for
 family15h

On Thu, Sep 26, 2013 at 04:54:32PM -0500, suravee.suthikulpanit@....com wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> 
> On AMD family15h, applying microcode patch on the a core (core0)
> would also affect the other core (core1) in the same compute unit.
> The driver would skip applying the patch on core1, but it still
> need to update kernel structures to reflect the proper patch level.
> 
> The current logic is not updating the struct ucode_cpu_info.cpu_sig.rev
> of the skipped core. This causes the /sys/devices/system/cpu/cpu1/microcode/version
> to report incorrect patch level as shown below:
> 
> [   10.708841] microcode: CPU0: new patch_level=0x0600063d
> [   10.714256] microcode: CPU1: patch_level=0x06000626
> [   10.719345] microcode: CPU2: patch_level=0x06000626
> [   10.748095] microcode: CPU2: new patch_level=0x0600063d
> [   10.753365] microcode: CPU3: patch_level=0x06000626
> [   10.758264] microcode: CPU4: patch_level=0x06000626
> [   10.786999] microcode: CPU4: new patch_level=0x0600063d

Actually, this is collect_cpu_info_amd()'s normal operation and shows
that there's no need to apply a microcode patch on the odd core since
the even core's ucode has been updated.

Actually you need something like that:

$ grep . cpu?/microcode/version
cpu0/microcode/version:0x6000822
cpu1/microcode/version:0x600081f
cpu2/microcode/version:0x6000822
cpu3/microcode/version:0x600081f
cpu4/microcode/version:0x6000822
cpu5/microcode/version:0x600081f
cpu6/microcode/version:0x6000822
cpu7/microcode/version:0x600081f

which shows the bug. Other than that, the patch is correct so please fix
the commit message and add x86@...nel.org to CC on the next submission
so that it gets picked by x86 people.

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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