From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suravee Suthikulpanit Subject: Re: x86/AMD: Nested hvm crashes in 4.3 Date: Thu, 27 Jun 2013 06:14:51 -0500 Message-ID: <51CC1EAB.1060103@amd.com> References: <51CB863B.6020405@amd.com> <51CC125E02000078000E10CE@nat28.tlf.novell.com> <51CC03C9.60800@amd.com> <51CC2B2702000078000E1178@nat28.tlf.novell.com> <51CC12EC.7050608@amd.com> <51CC150B.8040001@amazon.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51CC150B.8040001@amazon.de> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Egger, Christoph" Cc: Jacob Shin , Sherry Hurwitz , Keir Fraser , Jan Beulich , xen-devel List-Id: xen-devel@lists.xenproject.org On 6/27/2013 5:33 AM, Egger, Christoph wrote: > On 27.06.13 12:24, Suravee Suthikulpanit wrote: >> On 6/27/2013 5:08 AM, Jan Beulich wrote: >>>>>> On 27.06.13 at 11:20, Suravee Suthikulpanit >>>>>> wrote: >>>> On 6/27/2013 3:22 AM, Jan Beulich wrote: >>>>>>>> On 27.06.13 at 02:24, Suravee Suthikulanit >>>>>>>> wrote: >>>>>> I have found an issue in where the system crash right when I start >>>>>> another HVM guest inside an HVM guest. I have traced back to the >>>>>> patch >>>>>> which the issue started. >>>>>> >>>>>> commit f1bde87fc08ce8c818a1640a8fe4765d48923091 >>>>>> Author: Jan Beulich >>>>>> Date: Fri Feb 8 11:06:04 2013 +0100 >>>>>> >>>>>> x86: debugging code for testing 16Tb support on smaller >>>>>> memory systems >>>>>> >>>>>> Signed-off-by: Jan Beulich >>>>>> Acked-by: Keir Fraser >>>>> We had issues exposed by this patch before, but any such issue >>>>> would just have been masked before that patch (and would >>>>> surface on a system with more than 5Tb of memory anyway). >>>> The system I am having the issue has 48GB of memory. >>> Which is why you're seeing the problem only with the debugging >>> code enabled. >> Is the "debugging" enabled by default? I didn't specify any debug when >> building. > "Debugging" is enabled by default in the development tree. > >> How can I check and disable debugging? > In the toplevel source directory look into Config.mk > and set the line > > debug ?= y > > accordingly. Thank you for clarification. >>> (And of course I didn't really expect you to have >>> tried this on a huge memory system - they're just too rare still >>> for this to be likely.) >>> >>>>> So it is very unlikely for the patch itself to be at fault. >>>> I have traced the issue and found that the system crashing starts >>>> from this >>>> commit id and onward. >>>> (i.e. The system does not crash with commit id >>>> ed759d20249197cf87b338ff0ed328052ca3b8e7) >>>> So, I am still believe that this patch has somehow triggered the issue. >>> As said - I'm pretty certain this merely unmasked an already >>> lurking issue. >> I'm not quite sure what you meant here. Are you saying that this >> "crashing" is a known issue? > He means nestedhvm reveals an existing bug in his patch. > If he is right then you do not see nestedhvm crashing with a non-debug > xen-kernel (unless something else broke it). After I rebuilt Xen kernel with debug=n, the system no longer crash when starting npt-on-npt and shadown-on-npt guests. I was not able to get to the crash dump previously. I will try again tomorrow at work and will post them. Thank you, Suravee