virt: switch domain to Defined once migrated VM is stopped

When the VM is stopped on the source after migration, set VM status to
Down and also switch domain to Defined state. The domain is not running
and not all calls are available -- some would result in libvirt error.
Defined domain will throw virdomain.NotConnectedError which should be
handled by the caller.

Added handling of this exception into Vm._destroyVm* methods.
The methods are not called on not connected domain so this is only a
preventive measure to be on the safe side.

It would be more practical to change the domain to Defined much sooner,
ideally in _handle_libvirt_domain_stopped(). That would avoid any delays
especially from calling hooks. But postponing the change and doing it
together with state change later makes the behavior more predictable and
more consistent.

Bug-Url: https://bugzilla.redhat.com/2000046
Signed-off-by: Vojtech Juranek <[email protected]>
Signed-off-by: Tomáš Golembiovský <[email protected]>

lib/vdsm/virt/vm.py

@@ -1782,6 +1782,10 @@ def setDownStatus(self, code, exitReasonCode, exitMessage=''):
                 self.guestAgent.stop()
             except Exception:
                 pass
+            finally:
+                if self._dom.connected:
+                    self.log.info("Switching domain to Defined")
+                    self._dom = virdomain.Defined(self.id, self._dom.dom)
         if event_data:
             self.send_status_event(**event_data)
 
@@ -5384,7 +5388,6 @@ def _destroyVmGraceful(self):
         try:
             self._dom.destroyFlags(libvirt.VIR_DOMAIN_DESTROY_GRACEFUL)
         except libvirt.libvirtError as e:
-            # after successful migrations
             if (self.lastStatus == vmstatus.DOWN and
                     e.get_error_code() == libvirt.VIR_ERR_NO_DOMAIN):
                 self.log.info("VM '%s' already down and destroyed", self.id)
@@ -5400,6 +5403,8 @@ def _destroyVmGraceful(self):
                                           libvirt.VIR_ERR_SYSTEM_ERROR,):
                     safe_to_force = True
                 return response.error('destroyErr'), safe_to_force
+        except virdomain.NotConnectedError:
+            self.log.info("VM already down")
         return response.success(), safe_to_force
 
     def _destroyVmForceful(self):
@@ -5410,6 +5415,8 @@ def _destroyVmForceful(self):
                 "Failed to destroy VM '%s' forcefully (error=%i)",
                 self.id, e.get_error_code())
             return response.error('destroyErr')
+        except virdomain.NotConnectedError:
+            self.log.info("VM already down")
         return response.success()
 
     def _deleteVm(self):