Re: [libvirt] [PATCH] Xen: Add support for interface model='xenpv'

Xen HVM guests with PV drivers end up with two network interfaces for each configured interface. One of them being emulated by qemu and the other one paravirtual. As this might not be desirable, the attached patch provides a way for users to specify that only paravirtual network interface should be presented to the guest. The configuration was inspired by qemu/kvm driver, for which users can specify model='virtio' to use paravirtual network interface. The patch adds support for model='xenpv' which results in type=xenpv instead of type=ioemu (or nothing for newer xen versions) in guests native configuration. Xen's qemu ignores interfaces with type != ioemu and only paravirtual network device will be seen in the guest. A possible addition to this would be to force type=ioemu for all other models which would result in only emulated network device to be provided for an HVM guest on xen newer then XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU. No type would be configured when model is missing in domains XML. If you think this is a good idea, I'll prepare a second version of the patch.