From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:36349) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QRKZA-0007XK-IY for qemu-devel@nongnu.org; Tue, 31 May 2011 04:44:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QRKZ9-0000rr-ED for qemu-devel@nongnu.org; Tue, 31 May 2011 04:44:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19040) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QRKZ9-0000rf-7I for qemu-devel@nongnu.org; Tue, 31 May 2011 04:44:43 -0400 Date: Tue, 31 May 2011 09:44:29 +0100 From: "Daniel P. Berrange" Message-ID: <20110531084429.GA2671@redhat.com> References: <4DDAD5CF.5050805@redhat.com> <4DE0B4B1.1000407@web.de> <20110530081847.GC27062@amd.com> <4DE3A3EC.80201@siemens.com> <20110530143846.GA2957@fermat.math.technion.ac.il> <4DE3B1E2.7020006@siemens.com> <20110530151020.GB7855@amd.com> <4DE3B4A5.6050509@siemens.com> <4DE3B572.6030105@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <4DE3B572.6030105@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] drop -enable-nesting Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Anthony Liguori , Nadav Har'El , kvm , john cooper , Jan Kiszka , "qemu-devel@nongnu.org" , "Roedel, Joerg" On Mon, May 30, 2011 at 06:19:14PM +0300, Avi Kivity wrote: > On 05/30/2011 06:15 PM, Jan Kiszka wrote: > >On 2011-05-30 17:10, Roedel, Joerg wrote: > >> On Mon, May 30, 2011 at 11:04:02AM -0400, Jan Kiszka wrote: > >>> On 2011-05-30 16:38, Nadav Har'El wrote: > >>>> On Mon, May 30, 2011, Jan Kiszka wrote about "drop -enable-nestin= g (was: [PATCH 3/7] cpu model bug fixes and definition corrections...)": > >>>>> On 2011-05-30 10:18, Roedel, Joerg wrote: > >>>>>> On Sat, May 28, 2011 at 04:39:13AM -0400, Jan Kiszka wrote: > >>>>>> > >>>>>>> J=EF=BF=BDrg, how to deal with -enable-nesting in qemu-kvm to = align behavior > >>>>>>> with upstream? > >>>>>> > >>>>>> My personal preference is to just remove it. In upstream-qemu i= t is > >>>>>> enabled/disabled by +/-svm. -enable-nesting is just a historic = thing > >>>>>> which can be wiped out. > >>>> > >>>> "-enable-nesting" could remain as a synonym for enabling either V= MX or SVM > >>>> in the guest, depending on what was available in the host (becaus= e KVM now > >>>> supports both nested SVM and nested VMX, but not SVM-on-VMX or vi= ce versa). > >>> > >>> Why? Once nesting is stable (I think SVM already is), there is no = reason > >>> for an explicit enable. And you can always mask it out via -cpu. > >>> > >>> BTW, what are the defaults for SVM right now in qemu-kvm and upstr= eam? > >>> Enable if the modeled CPU supports it? > >> > >> qemu-kvm still needs -enable-nesting, otherwise it is disabled. Ups= tream > >> qemu should enable it unconditionally (can be disabled with -cpu ,-= svm). > > > >Then let's start with aligning qemu-kvm defaults to upstream? I guess > >that's what the diff I was citing yesterday is responsible for. > > > >In the same run, -enable-nesting could dump a warning on the console > >that this switch is obsolete and will be removed from future versions. >=20 > I think it's safe to drop -enable-nesting immediately. Dan, does > libvirt make use of it? Yes, but it should be safe to drop it. Currently, if the user specifies a CPU with the 'svm' flag present in libvirt guest XML, then we will pass args '-cpu ....+svm -enable-nesting'. So if we drop --enable-nesting= , then libvirt will simply omit it and everything should still work because we have still got +svm set. Daniel --=20 |: http://berrange.com -o- http://www.flickr.com/photos/dberrange= / :| |: http://libvirt.org -o- http://virt-manager.or= g :| |: http://autobuild.org -o- http://search.cpan.org/~danberr= / :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vn= c :|