linux-kernel - Re: v3.9 - CPU hotplug and microcode earlier loading hits a mutex deadlock (x86_cpu_hotplug_driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130508163249.GB369@phenom.dumpdata.com>
Date:	Wed, 8 May 2013 12:32:49 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Borislav Petkov <bp@...en8.de>, toshi.kani@...com,
	prarit@...hat.com, rafael.j.wysocki@...el.com,
	isimatu.yasuaki@...fujitsu.com
Cc:	linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, fenghua.yu@...el.com,
	xen-devel@...ts.xensource.com
Subject: Re: v3.9 - CPU hotplug and microcode earlier loading hits a mutex
 deadlock (x86_cpu_hotplug_driver_mutex)

On Wed, May 08, 2013 at 04:29:49PM +0200, Borislav Petkov wrote:
> On Wed, May 08, 2013 at 10:03:42AM -0400, Konrad Rzeszutek Wilk wrote:
> 
> [ … snip some funky BIOS code ]
> 
> > [here it shifts and continues on testing each CPU bit]
> > 
> > > Questions over questions...?
> > 
> > I probably went overboard with my answers :-)
> 
> Konrad, you're killing me! :-) You actually went and looked at the
> BIOS disassembly voluntarily. You must be insane, I think you should
> immediately go to the doctor now for a thorough checkup. :-)
> 
> I think I know who I can sling BIOS issues now to.

Great .. :-)
> 
> > > Looks like save_mc_for_early would need another, local mutex to fix that.
> > 
> > Let me try that. Thanks for the suggestion.
> 
> Ok, seriously now: yeah, this was just an idea, it should at least get
> the nesting out of the way.
> 
> About the BIOS deal: you're probably staring at some BIOS out there
> but is this the way that it is actually going to be implemented on
> the physical hotplug BIOS? I mean, I've only heard rumors about IVB
> supporting physical hotplug but do you even have access to such BIOS to
> verify?

Unfortunatly not. I am getting an IvyTown box so hopefully that has this
support. But I thought that Fenghua did since he mentioned in the patch.

Besides that I think this can also appear on VMWare if one is doing 
CPU hotplug and on some HP machines - let me CC the relevant people
extracted from drivers/acpi/processor_driver.c.
(see  https://lkml.org/lkml/2013/5/7/588 for the thread)

Rafael, do you know of any specific Intel hardware that has this implemented?
> 
> All I'm saying is, let's not hurry too much before we actually can
> really trigger this on baremetal.
> 
> Thanks.
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> Sent from a fat crate under my desk. Formatting is fine.
> --
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/