I have a new RHEV cluster where spice-xpi is refusing to connect. I stuffed the HostSubject in with the other options being sent to the plugin and suddenly it works. I'm not sure why in most cases it works without, and in this one it doesn't, except possibly that this rhev setup is new and completely up to date so it might be a requirement in 3.2 or in one of the latest updates for it.

Anyway, vms have a link to the host they're running on which in turn contain their subject, so it should be possible to pull in via the api