KVM live migration: handle failure

If the KVM live migration ends up in a 'failed' state it has been
aborted at the kvm level, and the machine is still running locally.
We support also the 'cancelled' state even though there should be no way
of reaching it, without manual intervention.

Reviewed-by: iustinp

lib/hypervisor/hv_kvm.py

@@ -506,6 +506,11 @@ class KVMHypervisor(hv_base.BaseHypervisor):
           done = True
         elif status == 'active':
           time.sleep(2)
+        elif status == 'failed' or status == 'cancelled':
+          if not live:
+            self._CallMonitorCommand(instance_name, 'cont')
+          raise errors.HypervisorError("Migration %s at the kvm level" %
+                                       status)
         else:
           logging.info("KVM: unknown migration status '%s'" % status)
           time.sleep(2)