Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751178AbaLIRX3 (ORCPT ); Tue, 9 Dec 2014 12:23:29 -0500 Received: from e06smtp15.uk.ibm.com ([195.75.94.111]:48500 "EHLO e06smtp15.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751043AbaLIRX1 (ORCPT ); Tue, 9 Dec 2014 12:23:27 -0500 Date: Tue, 9 Dec 2014 18:23:19 +0100 From: Cornelia Huck To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, dahi@linux.vnet.ibm.com, rusty@rustcorp.com.au, Christian Borntraeger , linux390@de.ibm.com, Martin Schwidefsky , Heiko Carstens , linux-s390@vger.kernel.org Subject: Re: [PATCH v3 4/6] virtio_ccw: rev 1 devices set VIRTIO_F_VERSION_1 Message-ID: <20141209182319.20ce2dec.cornelia.huck@de.ibm.com> In-Reply-To: <20141209122118.GF3993@redhat.com> References: <1418042769-25539-1-git-send-email-mst@redhat.com> <1418042769-25539-5-git-send-email-mst@redhat.com> <20141209120123.117ccfac.cornelia.huck@de.ibm.com> <20141209122118.GF3993@redhat.com> Organization: IBM Deutschland Research & Development GmbH Vorsitzende des Aufsichtsrats: Martina Koederitz =?UTF-8?B?R2VzY2jDpGZ0c2bDvGhydW5nOg==?= Dirk Wittkopp Sitz der Gesellschaft: =?UTF-8?B?QsO2Ymxpbmdlbg==?= Registergericht: Amtsgericht Stuttgart, HRB 243294 X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14120917-0021-0000-0000-000002130E78 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 9 Dec 2014 14:21:18 +0200 "Michael S. Tsirkin" wrote: > On Tue, Dec 09, 2014 at 12:01:23PM +0100, Cornelia Huck wrote: > > On Mon, 8 Dec 2014 15:06:03 +0200 > > "Michael S. Tsirkin" wrote: > > > diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c > > > index 789275f..f9f87ba 100644 > > > --- a/drivers/s390/kvm/virtio_ccw.c > > > +++ b/drivers/s390/kvm/virtio_ccw.c > > > @@ -758,6 +758,13 @@ static int virtio_ccw_finalize_features(struct virtio_device *vdev) > > > struct virtio_feature_desc *features; > > > struct ccw1 *ccw; This needs + struct virtio_device *vdev = &vcdev->vdev; to make it compile :) > > > > > > + if (vcdev->revision == 1 && > > > > If we decide to keep this check, it should be for rev >= 1, though. > > Fine, though this is theoretical, right? > Ican change this with a patch on top. > > > > + !__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) { > > > + dev_err(&vdev->dev, "virtio: device uses revision 1 " > > > + "but does not have VIRTIO_F_VERSION_1\n"); > > > + return -EINVAL; > > > + } > > > + > > > ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL); > > > if (!ccw) > > > return 0; > > > > I'm still not convinced by this change: I'd prefer to allow rev 1 > > without VERSION_1, especially as the core makes all its decisions based > > upon VERSION_1. > > At the moment, but this is an implementation detail. > This is exactly why I want this hard requirement in code. > > > > Unless someone else has a good argument in favour of > > this change. > > > Let's not commit to something we are not sure we > can support. > > We can always remove this code, but once we release > guest we won't be able to drop it. > OK, with your qemu patch on the host side this seems to be fine. No further objections from me for now. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/