From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49858) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZBS84-00013x-1H for qemu-devel@nongnu.org; Sat, 04 Jul 2015 14:25:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZBS80-00066X-NS for qemu-devel@nongnu.org; Sat, 04 Jul 2015 14:25:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52309) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZBS80-00066K-H8 for qemu-devel@nongnu.org; Sat, 04 Jul 2015 14:25:28 -0400 Date: Sat, 4 Jul 2015 20:25:23 +0200 From: "Michael S. Tsirkin" Message-ID: <20150704202136-mutt-send-email-mst@redhat.com> References: <20150701122334-mutt-send-email-mst@redhat.com> <5593CAEA.2000301@linux.vnet.ibm.com> <20150701131635-mutt-send-email-mst@redhat.com> <5593D2F9.6010600@linux.vnet.ibm.com> <20150701134925-mutt-send-email-mst@redhat.com> <5593E04C.3080204@linux.vnet.ibm.com> <20150701153151-mutt-send-email-mst@redhat.com> <5594A89E.10805@linux.vnet.ibm.com> <20150702070942-mutt-send-email-mst@redhat.com> <55966D87.1040505@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55966D87.1040505@linux.vnet.ibm.com> Subject: Re: [Qemu-devel] [PATCH v2 1/1] KVM s390 pci infrastructure modelling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Hong Bo Li Cc: cornelia.huck@de.ibm.com, borntraeger@de.ibm.com, sebott@linux.vnet.ibm.com, qemu-devel@nongnu.org, agraf@suse.de On Fri, Jul 03, 2015 at 07:09:59PM +0800, Hong Bo Li wrote: > >But I would like to note that pci device drivers require driver handshake > >before device goes away. > >IIUC s390 hotplug is immediate, which is a problem. > >Maybe doing the change will help make sure device removal is acked > >by guest before it happens? > > > > I did some prototype today. If define zpci first, the progress of unplug > will get complicated. The point is that you don't have to remove the zpci device at all. Remove pci device from zpci. I think the complication you refer to is the guest ack of the removal, isn't it? It's complicated, but it has a chance to actually work with pci device drivers. This, as opposed to just removing the device whenever host tells us to. > So I prefer defining vfio pci first. > And it looks like the vfio pci is the basic device, if we want this > vfio pci to work on s390, we have to define a zpci device to give some > additional information to it. if vfio connects to the bus internal to zpci, it can get things from the bus in a natural way. If zpci is connected to vfio, it becomes much messier. -- MST