Re: [libvirt] [PATCH 0/2] Xen: Add support for interface model='netfront'

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='netfront' which results in type=netfront 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. Four possible configuration scenarios follow: - no model specified in domain's XML - libvirt will behave like before this change; it will set type=ioemu for HVM guests on xen host which is not newer than XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU - covered by existing tests - PV guest, any model - no functional change, model is passed as is (and ignored by the hypervisor) - covered by existing tests (e.g., *-net-e1000.*) - HVM guest, model=netfront - type is set to "netfront", model is not specified - covered by new *-net-netfront.* tests - HVM guest, model != netfront - type is set to "ioemu", model is passed as is - covered by new *-net-ioemu.* tests The fourth scenario feels like a regression for xen newer than XEND_CONFIG_MAX_VERS_NET_TYPE_IOEMU as users who had a model specified in their guest's configuration won't see a paravirtual interface in their guests any more. On the other hand, the reason for specifying a model is most likely the fact that they want to use such model which implies emulated interface. Users of older xen won't be affected at all as their xen provides paravirtual interface regardless of the type used. In previous version of this patch, I used "xenpv" instead of "netfront" as it looked more like kvm/qemu's virtio. However, you can find several tips how to force PV network interface for HVM guest by using type="netfront" so I changed it to conform with those tips. It also matches guest's driver name used for that device. Jiri Denemark (2): Support for interface model='netfront' Tests for interface type/model configuration