From mboxrd@z Thu Jan 1 00:00:00 1970 From: Luiz Capitulino Subject: Re: [Qemu-devel] Re: [PATCH] qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back to non-accelerated mode Date: Fri, 4 Sep 2009 18:39:25 -0300 Message-ID: <20090904183925.63b0b5f7@doriath> References: <1252008114.3084.136.camel@blaa> <5d6222a80909031518h2bf804fbk1f7a52424d3e8649@mail.gmail.com> <1252048961.3144.8.camel@blaa> <1252080398.4625.47.camel@x200> <20090904163611.GC5132@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Marcelo Tosatti , Mark McLoughlin , qemu-devel@nongnu.org, kvm@vger.kernel.org, Glauber Costa To: Dustin Kirkland Return-path: Received: from mx1.redhat.com ([209.132.183.28]:8932 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933995AbZIDVje convert rfc822-to-8bit (ORCPT ); Fri, 4 Sep 2009 17:39:34 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Fri, 4 Sep 2009 14:38:30 -0500 Dustin Kirkland wrote: > On Fri, Sep 4, 2009 at 11:36 AM, Marcelo Tosatti= wrote: > > On Fri, Sep 04, 2009 at 11:06:38AM -0500, Dustin Kirkland wrote: > >> On Fri, 2009-09-04 at 08:22 +0100, Mark McLoughlin wrote: > >> > On Thu, 2009-09-03 at 19:18 -0300, Glauber Costa wrote: > >> > > On Thu, Sep 3, 2009 at 6:48 PM, Dustin Kirkland wrote: > >> > > > On Thu, Sep 3, 2009 at 3:01 PM, Mark McLoughlin wrote: > >> > > >> On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote: > >> > > >>> qemu-kvm: fix segfault when running kvm without /dev/kvm, = falling back > >> > > >>> to non-accelerated mode > >> > > >>> > >> > > >>> We're seeing segfaults on systems without access to /dev/k= vm. =C2=A0It > >> > > >>> looks like the global kvm_allowed is being set just a litt= le too late > >> > > >>> in vl.c. =C2=A0This patch moves the kvm initialization a b= it higher in the > >> > > >>> vl.c main, just after options processing, and solves the s= egfaults. > >> > > >>> We're carrying this patch in Ubuntu 9.10 Alpha. =C2=A0Plea= se apply > >> > > >>> upstream, or advise if and why this might not be the optim= al solution. > >> > > >> > >> > > >> Ah discussion about an alternative fix for this fizzled out= recently: > >> > > >> > >> > > >> =C2=A0http://www.mail-archive.com/kvm@vger.kernel.org/msg19= 890.html > >> > > > > >> > > > Ah, thanks Mark. =C2=A0In that thread, I found Daniel's sugg= estion the most > >> > > > reasonable, and user-friendly: > >> > > > > >> > > > On Mon, Jul 27, 2009 at 1:44 PM, Daniel P. Berrange wrote: > >> > > >> Well, we could go for logic like: > >> > > >> > >> > > >> =C2=A0* No arg given =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=3D>= try kvm, try kqemu, try tcg > >> > > >> =C2=A0* --accelmode arg given =3D> try $arg, and fail if un= available > >> > > >> > >> > > >> then libvirt would simply always supply --accelmode for all= VMs, > >> > > >> while people running qemu manually would get best available > >> > > I sent some patches to do that, but they were incomplete, and = I was > >> > > preempted by something else. > >> > > If you want, you can wait for my cycles to come back, or pick = from where I left > >> > >> Thanks for the pointer, Glauber. =C2=A0My cycles a bit constrained= too, but > >> I'll have a look when I get a chance. > >> > >> > In the meantime, can we commit to stable-0.11 either Dustin's fi= x or > >> > this: > >> > > >> > =C2=A0 http://git.et.redhat.com/?p=3Dqemu-fedora.git;a=3Dcommitd= iff;h=3Daa1620047b > >> > >> +1. =C2=A0We're looking for something agreeable in stable-0.11, th= at solves > >> the segfault and proceeds without VT acceleration. > > > > Dustin, > > > > Can you please resend the patch with the suggestion i made earlier,= for > > stable-0.11? >=20 > Sure, Marcelo. It's attached. >=20 > I tested it, and it still does avoid the segfault. >=20 > Luiz, could you re-test this patch on your side too? I'm getting rejections, are you sure it's against upstream?