From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41495) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1beOhx-0007SB-OX for qemu-devel@nongnu.org; Mon, 29 Aug 2016 11:42:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1beOhw-0004WR-RA for qemu-devel@nongnu.org; Mon, 29 Aug 2016 11:42:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58794) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1beOhw-0004WN-LW for qemu-devel@nongnu.org; Mon, 29 Aug 2016 11:42:44 -0400 Date: Mon, 29 Aug 2016 18:42:42 +0300 From: "Michael S. Tsirkin" Message-ID: <20160829184212-mutt-send-email-mst@kernel.org> References: <1466345649-64841-1-git-send-email-wei.w.wang@intel.com> <286AC319A985734F985F78AFA26841F7CB5968@shsmsx102.ccr.corp.intel.com> <20160829152451.GB18909@stefanha-x1.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160829152451.GB18909@stefanha-x1.localdomain> Subject: Re: [Qemu-devel] [virtio-comment] [PATCH] *** Vhost-pci RFC v2 *** List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: "Wang, Wei W" , "kvm@vger.kernel.org" , "qemu-devel@nongnu.org" , "virtio-comment@lists.oasis-open.org" , "pbonzini@redhat.com" On Mon, Aug 29, 2016 at 11:24:51AM -0400, Stefan Hajnoczi wrote: > On Mon, Jun 27, 2016 at 02:01:24AM +0000, Wang, Wei W wrote: > > On Sun 6/19/2016 10:14 PM, Wei Wang wrote: > > > This RFC proposes a design of vhost-pci, which is a new virtio device type. > > > The vhost-pci device is used for inter-VM communication. > > > > > > Changes in v2: > > > 1. changed the vhost-pci driver to use a controlq to send acknowledgement > > > messages to the vhost-pci server rather than writing to the device > > > configuration space; > > > > > > 2. re-organized all the data structures and the description layout; > > > > > > 3. removed the VHOST_PCI_CONTROLQ_UPDATE_DONE socket message, which > > > is redundant; > > > > > > 4. added a message sequence number to the msg info structure to identify > > > socket > > > messages, and the socket message exchange does not need to be blocking; > > > > > > 5. changed to used uuid to identify each VM rather than using the QEMU process > > > id > > > > > > > One more point should be added is that the server needs to send periodic socket messages to check if the driver VM is still alive. I will add this message support in next version. (*v2-AR1*) > > Either the driver VM could go down or the device VM (server) could go > down. In both cases there must be a way to handle the situation. > > If the server VM goes down it should be possible for the driver VM to > resume either via hotplug of a new device or through messages > reinitializing the dead device when the server VM restarts. > > Stefan I agree. And I do not think you need to send messages just to detect this, leave this to the hypervisor. -- MST