linux-kernel - Re: Issues with AMD microcode updates

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Date:	Tue, 24 Sep 2013 18:35:01 -0500
From:	Sherry Hurwitz <sherry.hurwitz@....com>
To:	Borislav Petkov <bp@...en8.de>
CC:	Henrique de Moraes Holschuh <hmh@....eng.br>,
	Jacob Shin <jacob.shin@....com>,
	Andreas Herrmann <herrmann.der.user@...glemail.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: Issues with AMD microcode updates

On 09/19/2013 11:44 AM, Borislav Petkov wrote:
> On Thu, Sep 19, 2013 at 11:58:34AM -0300, Henrique de Moraes Holschuh wrote:
>> Jacob, Andreas,
>>
>> I take care of the amd64 microcode update support for Debian, and I'm
>> receiving user reports of lockup issues with the AMD microcode driver in
>> several kernels.  This is about the runtime update interface,
>> /sys/devices/system/cpu/*/microcode/reload and
>> /sys/devices/system/cpu/microcode/reload.
>>
>> Basically, the issue is that the process that tries to write "1" to the
>> reload node gets stuck in "D" state on several kernel versions.
>>
>> I started by blacklisting several older kernels (e.g. I got a report of
>> 2.6.38 locking up), but recently I got a report of a lockup with kernel
>> 3.5.1.  Blacklisting everything before 3.10 is not exactly kosher, not when
>> I would have to blindly trust 3.0, 3.2 and 3.4 to not have whatever issue is
>> causing the lockups.
>>
>> IMHO that's the point where it becomes interesting to actually track down
>> the bug even if it apparently doesn't exist anymore on the more recent
>> kernels, and ensure that the stable/long-term kernels have the fix.  That
>> would also help distros blacklist microcode update on the broken kernels.
>>
>> Unfortunately, I don't own, or have access to, any boxes with an AMD
>> processor (let alone one with an AMD processor in need of a microcode
>> update) to bissect the problem.
>>
>> I'd appreciate if AMD (or anyone with an AMD processor, really) could help
>> me track this issue down.
>>
>> Debian bug reports:
>> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=717185
>> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=723081
> Well, both Andreas and Jacob don't work for AMD anymore. I could try to
> help with this but it'll be slow as I'm pretty busy with other stuff.
>
> Anyway, I'd suggest we look only on the long term kernels since they're
> the only ones which can get updates/fixes anyway.
>
> Now, how do I reproduce this? Writing 1 to .../reload on latest kernel
> works here. So I'd need a reproducer. Alternatively, I'd need a sysrq-l
> and sysrq-w from those systems with hung processes.
>
> Thanks.
>
You can direct AMD microcode issues to me now.
We are setting up some systems in the lab and trying to duplicate
the problem now.

Thanks.

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