linux-kernel - Re: [PATCH] x86: Fix thermal throttling reporting after kexec

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: <alpine.DEB.2.11.1510022233110.4500@nanos>
Date:	Fri, 2 Oct 2015 22:33:49 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Andi Kleen <ak@...ux.intel.com>
cc:	Andi Kleen <andi@...stfloor.org>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Fix thermal throttling reporting after kexec

On Thu, 1 Oct 2015, Andi Kleen wrote:
> On Thu, Oct 01, 2015 at 11:50:00PM +0200, Andi Kleen wrote:
> > > I see it under the correctness aspect. Mop up before you shut down.
> > 
> > Ok. I suspect if you want to clean up all registers there's much more
> > to do.
> > 
> > BTW there's a small danger in it: if we ever crash accessing on
> > of those registers panic may end up looping.
> 
> I thought more about it. Since this is per logical CPU state
> the cleanup cannot be done in a normal shutdown callback (which
> only runs on one CPU), but needs some kind of global IPI/NMI.
> 
> IPI could deadlock, so it would need to be NMI.
> 
> KVM already has one, but would need to re-organize that into
> first into a generic callback infrastructure.
> 
> I don't think so much change is worth it for this one
> somewhat dubious case. NMI code is also tricky and it's
> probably better to keep the shut down paths as simple
> and reliable as possible. Do you agree?

Yes. Makes sense.

Thanks for analysing it.

	tglx
--
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/