From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57323) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZHqR0-0002Ye-8N for qemu-devel@nongnu.org; Wed, 22 Jul 2015 05:35:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZHqQx-0002M6-1r for qemu-devel@nongnu.org; Wed, 22 Jul 2015 05:35:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33315) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZHqQw-0002M1-TB for qemu-devel@nongnu.org; Wed, 22 Jul 2015 05:35:26 -0400 Message-ID: <55AF63CB.4030008@redhat.com> Date: Wed, 22 Jul 2015 17:35:07 +0800 From: Jason Wang MIME-Version: 1.0 References: <1437544792-3949-1-git-send-email-jasowang@redhat.com> <1437544792-3949-3-git-send-email-jasowang@redhat.com> <20150722105843.41d22942.cornelia.huck@de.ibm.com> In-Reply-To: <20150722105843.41d22942.cornelia.huck@de.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V3 2/3] virtio-blk: fail get_features when both scsi and 1.0 were set List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck Cc: pbonzini@redhat.com, qemu-devel@nongnu.org, mst@redhat.com On 07/22/2015 04:58 PM, Cornelia Huck wrote: > On Wed, 22 Jul 2015 13:59:51 +0800 > Jason Wang wrote: > >> SCSI passthrough was no longer supported in virtio 1.0, so this patch >> fail the get_features() when both 1.0 and scsi is set. And also only >> advertise VIRTIO_BLK_F_SCSI for legacy virtio-blk device. >> >> Signed-off-by: Jason Wang >> --- >> hw/block/virtio-blk.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c >> index 4c27974..4716c3e 100644 >> --- a/hw/block/virtio-blk.c >> +++ b/hw/block/virtio-blk.c >> @@ -731,7 +731,14 @@ static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features, >> virtio_add_feature(&features, VIRTIO_BLK_F_GEOMETRY); >> virtio_add_feature(&features, VIRTIO_BLK_F_TOPOLOGY); >> virtio_add_feature(&features, VIRTIO_BLK_F_BLK_SIZE); >> - virtio_add_feature(&features, VIRTIO_BLK_F_SCSI); >> + if (__virtio_has_feature(features, VIRTIO_F_VERSION_1)) { >> + if (s->conf.scsi) { >> + error_setg(errp, "Virtio 1.0 does not support scsi passthrough!"); >> + return 0; >> + } >> + } else { >> + virtio_add_feature(&features, VIRTIO_BLK_F_SCSI); >> + } >> >> if (s->conf.config_wce) { >> virtio_add_feature(&features, VIRTIO_BLK_F_CONFIG_WCE); > Do we advertise F_SCSI even if scsi is not configured in order to keep > the same bits as before? I'm afraid I don't remember, that thread was > long :/ > > I'm asking because I'd like to depend on that bit to decide whether I > can negotiate revision 1 for ccw and subsequently offer VERSION_1. It > would be an easy thing to do, and I'd like to avoid mucking around with > device-specific configuration from the transport. I don't see much difference. Both of our patches needs to set scsi to off to have 1.0 device. And I don't see advantages that did it from transport. If it has, we probably need something similar in virtio-pci. > > To illustrate what I'm talking about, my current patchset for virtio-1 > on ccw is here: > > git://github.com/cohuck/qemu virtio-1-ccw-2.5 > Looks like patch "virtio-blk: scsi is legacy only" breaks backward compatibility because VIRTIO_BLK_F_SCSI was not notified when scsi is off. Thanks