On 09/02/2016 09:27 PM, Stefan Hajnoczi wrote: > On Fri, Sep 02, 2016 at 12:27:25AM +0800, Wei Wang wrote: > > On 09/01/2016 12:07 AM, Stefan Hajnoczi wrote: > > > On Tue, Aug 30, 2016 at 10:08:01AM +0000, Wang, Wei W wrote: > > > > On Monday, August 29, 2016 11:25 PM, Stefan Hajnoczi wrote: > > > > > To: Wang, Wei W <wei.w.wang@xxxxxxxxx> > > > > > Cc: kvm@xxxxxxxxxxxxxxx; qemu-devel@xxxxxxxxxx; virtio- > > > > > comment@xxxxxxxxxxxxxxxxxxxx; mst@xxxxxxxxxx; > > > > > pbonzini@xxxxxxxxxx > > > > > Subject: Re: [virtio-comment] [PATCH] *** Vhost-pci RFC v2 *** > > > > > > > > > > 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. > > > > I got feedbacks from people that the name of device VM and > > > > driver VM are difficult to remember. Can we use client (or > > > > frontend) VM and server (or backend) VM in the discussion? I > > > > think that would sound more straightforward :) > > > We discussed this in a previous email thread. > > > > > > Device and driver are the terms used by the virtio spec. Anyone > > > dealing with vhost-pci design must be familiar with the virtio spec. > > > > > > I don't see how using the terminology consistently can be > > > confusing, unless these people haven't looked at the virtio spec. > > > In that case they have no business with working on vhost-pci > > > because virtio is a prerequisite :). > > > > > > Stefan > > I don't disagree :) > > But "frontend/backend" is also commonly used in descriptions in > > virtio related stuff, and it seems that more people like it. It's > > also easier to describe some components in the design (e.g. a > > backend functionality like vhost-pci-net). I am not sure if you guys are also OK with it. > > If you want to use frontend/backend I don't mind. It seems clear to me. Thanks Stefan. Marc-André and I just got different thoughts about a design direction. I prefer to have all the frontend virtio devices (net, scsi, console etc.) from the same VM to be supported by one backend vhost-pci device (N-1), while Marc-André prefers to have each frontend virtio device be supported by a backend vhost-pci device (N-N). If possible, hope you, Michael or other more people could also join our review and discussion to finalize the design. Thanks. Best, Wei -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
