Re: [Qemu-devel] [virtio-comment] Re: [PATCH v1] docs/vhost-user: extend the vhost-user protocol to support the vhost-pci based inter-vm communication

[Wang, Wei W]

On Tuesday, November 8, 2016 7:36 PM, Wei Wang wrote:

Missed this one:
> > Currently all requests (including VHOST_USER_SET_FEATURES) are coming
> > from the Master. I don't understand yet the purpose of
> > VHOST_USER_SET_PEER_CONNECTION to propose an alternative, but I would
> > rather keep the unidirectional communication if possible.

The VHOST_USER_SET_PEER_CONNECTION is proposed here to turn “on/off” the device 
connection status. For example, when the master side VM wants to turn down, the 
virtio-net driver sets the virtio-net device’s PEER_CONNECTION status to “off”, 
which needs to first synchronize with the vhost-pci device using this message. 
In return, the vhost-pci device will send 
VHOST_USER_SET_PEER_CONNECTION(cmd=OFF) to the virtio-net device, then the 
status is set to OFF, and the driver is ok to unload. (Same for the vhost-pci 
driver to unload)

Best,
Wei