From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:34226)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1TQGpX-0001Tm-V2
	for qemu-devel@nongnu.org; Mon, 22 Oct 2012 08:10:08 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1TQGpR-0004C4-29
	for qemu-devel@nongnu.org; Mon, 22 Oct 2012 08:10:03 -0400
Received: from mx1.redhat.com ([209.132.183.28]:28481)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1TQGpQ-0004Bc-QP
	for qemu-devel@nongnu.org; Mon, 22 Oct 2012 08:09:56 -0400
Date: Mon, 22 Oct 2012 15:12:00 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20121022131159.GB16851@redhat.com>
References: <20121018150127.GA29551@redhat.com>
 <50851AB2.1060304@suse.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
In-Reply-To: <50851AB2.1060304@suse.de>
Content-Transfer-Encoding: quoted-printable
Subject: Re: [Qemu-devel] [PATCHv3] qemu: enable PV EOI for qemu 1.3
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>
Cc: Anthony Liguori <aliguori@us.ibm.com>, Eduardo Habkost <ehabkost@redhat.com>, Jan Kiszka <jan.kiszka@siemens.com>, Don Slutz <Don@CloudSwitch.com>, qemu-devel@nongnu.org, Blue Swirl <blauwirbel@gmail.com>, Igor Mammedov <imammedo@redhat.com>

On Mon, Oct 22, 2012 at 12:06:42PM +0200, Andreas F=E4rber wrote:
> Am 18.10.2012 17:01, schrieb Michael S. Tsirkin:
> > Enable KVM PV EOI by default. You can still disable it with
> > -kvm_pv_eoi cpu flag. To avoid breaking cross-version migration,
> > enable only for qemu 1.3 (or in the future, newer) machine type.
> >=20
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>=20
> Thanks for updating,
>=20
> Reviewed-by: Andreas F=E4rber <afaerber@suse.de>
>=20
> The commit message is not so telling whether there are any downsides
> (security implications?) to enabling this by default if supported,

I don't think there could be security downsides because all this does
is tell guest about the feature in a convenient way.
A well behaved guest doesn't use a feature unless it's listed but
that's irrelevant for security.

> so
> I'll leave it to Anthony to ack/apply this.
>=20
> Regards,
> Andreas

It used to be enabled. It was turned off in
ef8621b1a3b199c348606c0a11a77d8e8bf135f1
because it affected migration format and doing that
just before the release seemed too risky.


> --=20
> SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg, Germany
> GF: Jeff Hawn, Jennifer Guild, Felix Imend=F6rffer; HRB 16746 AG N=FCrn=
berg