This patch series resolves:
https://bugzilla.redhat.com/show_bug.cgi?id=805071
It enhances virDomainUpdateDeviceFlags for network devices to allow
live change of just about everything that doesn't affect what hardware
is presented to the guest (e.g. the device model, mac address, PCI
address, and other PCI attributes can't be changed, but the
type/details of the connection to the host network can be changed,
including bandwidth, type of tap device, vlan setting, nwfilter).
I haven't tested the new code yet beyond compiling, but wanted to get
the patches up on the list since the weekend is coming. I'll be
testing this morning and hopefully won't encounter any major problems.