[libvirt] [PATCH 0/2] qemu: support setting vlan tag for <interface

This would have been just one small patch, but there was a deficiency in the low level functions to save and restore pre-existing state of a virtual function. I have tested these patches on a RHEL6 machine with an SR-IOV adapter, and it properly handled the save/set .. [attach-to-guest] .. [detach] .. restore cycle both when the original state of the VF had a vlan tag and not, and when the guest was requesting a vlan tag, and not. (Now I'm wondering if this would also work for macvtap "passthrough" mode when the adapter used is a VF - it looks like the only thing stopping it is that the code to save / set / restore in that mode uses the device name of the vf, rather than referring to it as <physical device> vf <n>; since only VFs understand setting the vlan tag, the lower level code just assumes it can't be done)