Rawhide (2.6.26-rc) guests running on a rawhide host is broken at the moment,
because of this:

  http://www.mail-archive.com/kvm@vger.kernel.org/msg01023.html

If you set earlyprintk=serial, you just see the guest hang at e.g.:

     0MB HIGHMEM available.
     511MB LOWMEM available.

To fix rawhide, we can either:

  1) Wait for Avi to send a fix to Linus and have the fix pulled in naturally

  2) Take whatever fix Avi accepts into git and backporting 

  3) Just disabling CONFIG_KVM_GUEST for now

Since it's been broken for quite a while, I'm just assuming we'll do (1), but
that doesn't happen soon we should probably just do (3)