Comment 5 for bug 1203193

After reading live-migration related codes in openstack side just now, I guess most likely it's a bug of kvm.
openstack only checks the configuration and configures network for the vm by those two methods (pre_live_migration & post_live_migration),
the rest thing is left to kvm to do by invoking it's virDomainMigrateToURI method of libvirtmod module which is realized using C language.

I don't see the code of virDomainMigrateToURI method, but I guess it's possible steps are as bellow:
1, share pubkey between the two hosts with ssh-copy id root@targethost from "sourcehost"
2, copy the vm's disk from the source host to the target host by: dd if=/dev/<vgname>/<lvname> | ssh root@targethost 'dd of=/dev/<vgname>/<lvname>'
3, dump the xml definitions virsh dumpxml <vm> dump.xml
4, transfer xml-file scp dump.xml root@targethost:/root/
5, define the machine on target virsh define dump.xml the machine is then created from the xml.
6, virsh start vm

so parthipan, could you help confirm following two things:
1) are you configuring the share ssh pubkey for root account ?
2) have you tried block live migration by libvirt's CLI directly, rather than openstack's CLI. like:
   virsh migrate --live --copy-storage-all --verbose <vm-name> qemu+ssh://<target-host>/system