From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH v3] enable x2APIC without interrupt remapping under KVM Date: Fri, 10 Jul 2009 13:29:46 -0700 Message-ID: References: <20090629132926.GB20289@redhat.com> <20090630092623.GI20289@redhat.com> <4A4A476C.2070305@redhat.com> <4A4A6499.9000406@redhat.com> <1246488808.27006.10691.camel@localhost.localdomain> <1246983280.27006.10707.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Gleb Natapov , "linux-kernel\@vger.kernel.org" , Sheng Yang , "kvm\@vger.kernel.org" , "garyhade\@us.ibm.com" To: suresh.b.siddha@intel.com Return-path: Received: from out02.mta.xmission.com ([166.70.13.232]:49299 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752222AbZGJU3v (ORCPT ); Fri, 10 Jul 2009 16:29:51 -0400 In-Reply-To: <1246983280.27006.10707.camel@localhost.localdomain> (Suresh Siddha's message of "Tue\, 07 Jul 2009 09\:14\:40 -0700") Sender: kvm-owner@vger.kernel.org List-ID: Suresh Siddha writes: > On Wed, 2009-07-01 at 17:17 -0700, Eric W. Biederman wrote: >> Suresh Siddha writes: >> > Among number of experiments you have tried in the past to fix this, have >> > you tried the experiment of explicitly clearing the remoteIRR by >> > changing the trigger mode to edge and then back to level. >> > >> > Is there a problem with this? >> >> The problem I had wasn't remoteIRR getting stuck, but the symptoms >> were largely the same. I did try changing the trigger mode to edge >> and back and that did not unstick the ioapic in all cases. >> > > I did some experiments locally here yesterday and on my old ICH5 based > system, I couldn't reset the remoteIRR by changing the trigger mode to > edge and then back to level. > > However what worked was an explicit eoi to the io-apic using the > respective vector. > > I guess we need to try both the things based on perhaps io-apic version > etc. In part the deep problems I ran into was something other than RemoteIRR. If it was something as simple as the ioapic being in a documented state I would have kept looking. At the very least the RemoteIRR bit was not set in some of the cases I encountered. > But what I am nervous about is, did you try both these things aswell and > still saw stuck interrupts? Yes. The work arounds were in the code so I tried them. > I will cleanup my code and post it, so that we can try on different > systems. If this still doesn't work on certain HW platforms, atleast our > experiments of what works and what doesn't work and on what platforms > will be documented on the web. Sounds reasonable. My apologies for the long delayed reply. I want to work on this but I have higher priorities. Eric