From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45357) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dStiU-00007u-GN for qemu-devel@nongnu.org; Wed, 05 Jul 2017 19:28:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dStiP-0006OF-GD for qemu-devel@nongnu.org; Wed, 05 Jul 2017 19:28:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46226) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dStiP-0006Mc-9s for qemu-devel@nongnu.org; Wed, 05 Jul 2017 19:28:13 -0400 Date: Thu, 6 Jul 2017 02:28:02 +0300 From: "Michael S. Tsirkin" Message-ID: <20170706022434-mutt-send-email-mst@kernel.org> References: <20170628190047.26159-1-dgilbert@redhat.com> <20170628190047.26159-26-dgilbert@redhat.com> <20170705005657-mutt-send-email-mst@kernel.org> <20170705171617.GD2284@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170705171617.GD2284@work-vm> Subject: Re: [Qemu-devel] [RFC 25/29] vhu: enable = false on get_vring_base List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: qemu-devel@nongnu.org, a.perevalov@samsung.com, marcandre.lureau@redhat.com, maxime.coquelin@redhat.com, quintela@redhat.com, peterx@redhat.com, lvivier@redhat.com, aarcange@redhat.com On Wed, Jul 05, 2017 at 06:16:17PM +0100, Dr. David Alan Gilbert wrote: > * Michael S. Tsirkin (mst@redhat.com) wrote: > > On Wed, Jun 28, 2017 at 08:00:43PM +0100, Dr. David Alan Gilbert (git) wrote: > > > From: "Dr. David Alan Gilbert" > > > > > > When we receive a GET_VRING_BASE message set enable = false > > > to stop any new received packets modifying the ring. > > > > > > Signed-off-by: Dr. David Alan Gilbert > > > > I think I already reviewed a similar patch. > > Yes you replied to my off-list mail; I hadn't got > around to fixing it yet. > > > Spec says: > > Client must only process each ring when it is started. > > but in that reply you said the spec said > > Client must only pass data between the ring and the > backend, when the ring is enabled. > > So does the spec say 'started' or 'enabled' Both. Ring processing is limited by ring being started. Passing actual data - by ring also being enabled. With ring started but disabled you drop all packets. > (Pointer to the spec?) It's part of QEMU source: docs/interop/vhost-user.txt > > IMHO the real fix is to fix client to check the started > > flag before processing the ring. > > Yep I can do that. I was curious however whether it was > specified as 'started' or 'enabled' or both. > > Dave > > > > --- > > > contrib/libvhost-user/libvhost-user.c | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c > > > index ceddeac74f..d37052b7b0 100644 > > > --- a/contrib/libvhost-user/libvhost-user.c > > > +++ b/contrib/libvhost-user/libvhost-user.c > > > @@ -652,6 +652,7 @@ vu_get_vring_base_exec(VuDev *dev, VhostUserMsg *vmsg) > > > vmsg->size = sizeof(vmsg->payload.state); > > > > > > dev->vq[index].started = false; > > > + dev->vq[index].enable = false; > > > if (dev->iface->queue_set_started) { > > > dev->iface->queue_set_started(dev, index, false); > > > } > > > -- > > > 2.13.0 > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK