[libvirt-users] SR-IOV Pool Availability

If I'm using the SR-IOV Pool assignment method (from http://wiki.libvirt.org/page/Networking#Assignment_from_a_pool_of_SRIOV_VFs_... ), how would I check how many virtual functions are already in use? Is there a method other then looping through all the active guests and determining if they're using the SR-IOV interface?