From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46987) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cHTKK-0003Q6-Vg for qemu-devel@nongnu.org; Thu, 15 Dec 2016 05:31:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cHTKH-0008PY-S6 for qemu-devel@nongnu.org; Thu, 15 Dec 2016 05:31:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49314) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cHTKH-0008Om-KA for qemu-devel@nongnu.org; Thu, 15 Dec 2016 05:31:49 -0500 Date: Thu, 15 Dec 2016 10:31:45 +0000 From: Stefan Hajnoczi Message-ID: <20161215103145.GG2762@stefanha-x1.localdomain> References: <20161214163035.3297-1-maxime.coquelin@redhat.com> <20161215073808.GB26169@stefanha-x1.localdomain> <20161215092656.2e1244c0.cornelia.huck@de.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="L+ofChggJdETEG3Y" Content-Disposition: inline In-Reply-To: <20161215092656.2e1244c0.cornelia.huck@de.ibm.com> Subject: Re: [Qemu-devel] [PATCH v3] virtio-pci: Fix cross-version migration with older machines List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck Cc: Stefan Hajnoczi , Maxime Coquelin , mdroth@linux.vnet.ibm.com, qemu-devel@nongnu.org, mst@redhat.com, marcel@redhat.com, "Dr . David Alan Gilbert" --L+ofChggJdETEG3Y Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Dec 15, 2016 at 09:26:56AM +0100, Cornelia Huck wrote: > On Thu, 15 Dec 2016 07:38:09 +0000 > Stefan Hajnoczi wrote: >=20 > > On Wed, Dec 14, 2016 at 05:30:35PM +0100, Maxime Coquelin wrote: > > > This patch fixes a cross-version migration regression introduced > > > by commit d1b4259f ("virtio-bus: Plug devices after features are > > > negotiated"). > > >=20 > > > The problem is encountered when host's vhost backend does not support > > > VIRTIO_F_VERSION_1, and migration is initiated from a v2.7 or prior > > > machine with virtio-pci modern capabilities enabled to a v2.8 machine. > > >=20 > > > In this case, modern capabilities get exposed to the guest by the sou= rce, > > > whereas the target will detect version 1 is not supported so will only > > > expose legacy capabilities. > > >=20 > > > The problem is fixed by introducing a new "x-ignore-backend-features" > > > property, which is set in v2.7 and prior compatibility modes. Doing t= his, > > > v2.7 machine keeps its broken behaviour (enabling modern while version > > > is not supported), and newer machines will behave correctly. > > >=20 > > > Reported-by: Michael Roth > > > Suggested-by: Stefan Hajnoczi > > > Cc: Michael S. Tsirkin > > > Cc: Cornelia Huck > > > Cc: Dr. David Alan Gilbert > > > Reviewed-by: Marcel Apfelbaum > > > Reviewed-by: Stefan Hajnoczi > > > Tested-by: Michael Roth > > > Signed-off-by: Maxime Coquelin > > > --- > > >=20 > > > V3 fixes commit message with the new property name. > > > V2 changes the naming as proposed by Michael T.and Cornelia, and > > > fixes commit message. > > >=20 > > > hw/virtio/virtio-pci.c | 5 ++++- > > > hw/virtio/virtio-pci.h | 1 + > > > include/hw/compat.h | 4 ++++ > > > 3 files changed, 9 insertions(+), 1 deletion(-) > >=20 > > Thanks, applied to my staging tree: > > https://github.com/stefanha/qemu/commits/staging > >=20 > > Stefan >=20 > Hm, missing my R-b I gave for v2... feel free to add >=20 > Reviewed-by: Cornelia Huck >=20 > if you still want to change it. Sorry, the R-b didn't make it into v2.8.0-rc4. The patch management scripts I use apply all R-b for a single email thread. They do not look at previous revisions (it would be hard to tell which R-b still stand and which do not). The usual solution is for the patch author to include previous R-b in new revisions as long as code changes aren't substantial. Stefan --L+ofChggJdETEG3Y Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJYUnERAAoJEJykq7OBq3PICwkH/0dJRD7cqolZvcmE/Xfm7W0V LnIvV185bRKrYPqLzqUP6szgQTtopKo48b5WQfDtI4F8FpLpBwoFEwaX2He4vbCR p/oG3oHgb+E8v5qiHdwI5suXKgDx1BtXfbuXsZtecnnVsi5hAPS3QcxfswTnGy0C z9qy3IEBAsFTJwQ4mK6M/UJNAfJEOf0pbsHBGqvQEJAm0CS/JN/XmSe4w82IOPcN O4Ok3LZTi/ZAPMN0DZnk0pNTQqTMUXUTylbUP5cNIRNymNrQxycWo5M4GvyKsReo 2RHUbeDCRkURI+WRNxUbTAdQ0O1HeSGPwjM7564Th27bzoWy60EfAYLWy6MASv4= =06yy -----END PGP SIGNATURE----- --L+ofChggJdETEG3Y--