Xen's day is past
They are still fussing around with Xen? Everybody I know couldn't move to KVM fast enough as soon as it became solid, seems like a lifetime ago now.
Xen badly mishandled selling itself to get linux to build in DOM0 support, and it's much too late to change the momentum now. I still remember the bad old days of RHEL5, pre-KVM, with the horrible headache of a completely separate, specialized kernel implementing DOM0 support.