Re: [Qemu-devel] [virtio-comment] [PATCH] *** Vhost-pci RFC v2 ***

[Stefan Hajnoczi]

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

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