From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: Problems on AMD laptops Date: Mon, 29 Jun 2009 20:26:13 +0200 Message-ID: <20090629182613.GH4182@8bytes.org> References: <4A48C47D.3070908@redhat.com> <20090629143915.GG4182@8bytes.org> <4A48D5B6.9040607@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: KVM list To: Avi Kivity Return-path: Received: from 8bytes.org ([88.198.83.132]:40094 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750860AbZF2S0L (ORCPT ); Mon, 29 Jun 2009 14:26:11 -0400 Content-Disposition: inline In-Reply-To: <4A48D5B6.9040607@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Jun 29, 2009 at 05:54:46PM +0300, Avi Kivity wrote: > On 06/29/2009 05:39 PM, Joerg Roedel wrote: >> On Mon, Jun 29, 2009 at 04:41:17PM +0300, Avi Kivity wrote: >> >>> kerneloops.org shows tons of oopses on amd, see >>> http://www.kerneloops.org/oops.php?number=79008. I suspect this has to >>> do with resuming a laptop while a guest is running. Can anyone confirm >>> or deny? >>> >> >> I havn't verified this yet but it may have to do with dirty caches that >> are not written back to memory in suspend-to-ram and are thus lost. > > Wouldn't that kill resume generally, not just kvm on amd? Its a race condition which may be more likely on one hardware than on another. I remember similar bugs fixed by Mark in the past. >> The >> resume code-path looks otherwise sane to me. The only thing I can >> imagine is that a bit in the cpu_hardware_enabled cpumask is wrong after >> resume. >> > > I saw some of these oopses on cpu 0, which had better be plugged in. Yeah, but if this bit is set to 0 on suspend and this change does not make it from cache to main memory it can still be 1 on resume. And virtualization hardware will not be re-enabled then. Anyway, this was only a guess from me. I think we should reproduce this oops and find out what is really going on. >> Btw. it is guaranteed that with cpu-hotplug the cpu isn't already >> executing processes when the CPU_ONLINE event call chain is called? >> At least the CPU is marked online and active at that point in time. >> > > Yes: > > static struct notifier_block kvm_cpu_notifier = { > .notifier_call = kvm_cpu_hotplug, > .priority = 20, /* must be > scheduler priority */ > }; Ok. > One thing I think is missing is a call to svm_cpu_init() on real hotplug. Yes, true. There is no svm_data allocated for cpus not online on module load. Joerg