From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: vpmu=1 and running 'perf top' within a PVHVM guest eventually hangs dom0 and hypervisor has stuck vCPUS. Romley-EP (model=45, stepping=2) Date: Tue, 12 Mar 2013 16:31:19 -0400 Message-ID: <20130312203119.GC23081@phenom.dumpdata.com> References: <20130312173055.GA11000@phenom.dumpdata.com> <513F7913.2090003@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <513F7913.2090003@oracle.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Boris Ostrovsky Cc: xen-devel@lists.xensource.com, jun.nakajima@intel.com, qing.he@intel.com, eddie.dong@intel.com, dietmar.hahn@ts.fujitsu.com, jbeulich@suse.com, suravee.suthikulpanit@amd.com, jiongxi.li@intel.com List-Id: xen-devel@lists.xenproject.org On Tue, Mar 12, 2013 at 02:50:59PM -0400, Boris Ostrovsky wrote: > On 03/12/2013 01:30 PM, Konrad Rzeszutek Wilk wrote: > >This issue I am encountering seems to only happen on multi-socket > >machines. > > I believe I was able to reproduce this (once) on my laptop. > > >It also does not help that the only multi-socket box I have is > >an Romley-EP (so two socket SandyBridge CPUs). The other > >SandyBridge boxes I've (one socket) are not showing this. Granted > >they are also a different model (42). > > > >The problem is that when I run 'perf top' within an SMP PVHVM > >guest, after a couple of seconds or minutes the guest hangs. > >Hypervisor ends up stuck too looping, and then the dom0 ends > >up hanging as well. > > > >Dumping the cpu registers (Ctrl-A x3, then 'd' > >shows that the guest is pretty firmly stuck in vmx_vmexit_handler: > > > >(XEN) [] vmx_vmexit_handler+0x22f/0x174 > > And in my case this address is the second instruction after STI, i.e. we > are right at the point where interrupts got enabled. > > So I am wondering whether this has something to do with the counter > overflow interrupt (which I believe is an NMI). Interestingly enough, if I run the PVHVM guest with 'nowatchdog' it runs fine!