Merge "Fallback to legacy live migration if config error"

nova/tests/virt/libvirt/test_driver.py

@@ -5624,6 +5624,61 @@ class LibvirtConnTestCase(test.TestCase):
 
         db.instance_destroy(self.context, instance_ref['uuid'])
 
+    @mock.patch.object(libvirt, 'VIR_DOMAIN_XML_MIGRATABLE', 8675, create=True)
+    def test_live_migration_raises_unsupported_config_exception(self):
+        # Tests that when migrateToURI2 fails with VIR_ERR_CONFIG_UNSUPPORTED,
+        # migrateToURI is used instead.
+
+        # Preparing data
+        instance_ref = fake_instance.fake_instance_obj(
+            self.context, **self.test_instance)
+
+        # Preparing mocks
+        vdmock = self.mox.CreateMock(libvirt.virDomain)
+        self.mox.StubOutWithMock(vdmock, 'migrateToURI2')
+        self.mox.StubOutWithMock(vdmock, 'migrateToURI')
+        _bandwidth = CONF.libvirt.live_migration_bandwidth
+        vdmock.XMLDesc(libvirt.VIR_DOMAIN_XML_MIGRATABLE).AndReturn(
+                FakeVirtDomain().XMLDesc(0))
+        unsupported_config_error = libvirt.libvirtError('ERR')
+        unsupported_config_error.err = (libvirt.VIR_ERR_CONFIG_UNSUPPORTED,)
+        # This is the first error we hit but since the error code is
+        # VIR_ERR_CONFIG_UNSUPPORTED we'll try migrateToURI.
+        vdmock.migrateToURI2(CONF.libvirt.live_migration_uri % 'dest', None,
+                             mox.IgnoreArg(), mox.IgnoreArg(), None,
+                             _bandwidth).AndRaise(unsupported_config_error)
+        # This is the second and final error that will actually kill the run,
+        # we use TestingException to make sure it's not the same libvirtError
+        # above.
+        vdmock.migrateToURI(CONF.libvirt.live_migration_uri % 'dest',
+                            mox.IgnoreArg(), None,
+                            _bandwidth).AndRaise(test.TestingException('oops'))
+
+        def fake_lookup(instance_name):
+            if instance_name == instance_ref.name:
+                return vdmock
+
+        self.create_fake_libvirt_mock(lookupByName=fake_lookup)
+
+        def fake_recover_method(context, instance, dest, block_migration):
+            pass
+
+        graphics_listen_addrs = {'vnc': '0.0.0.0', 'spice': '127.0.0.1'}
+        migrate_data = {'pre_live_migration_result':
+                {'graphics_listen_addrs': graphics_listen_addrs}}
+        conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+
+        self.mox.StubOutWithMock(
+            conn, '_check_graphics_addresses_can_live_migrate')
+        conn._check_graphics_addresses_can_live_migrate(graphics_listen_addrs)
+        self.mox.ReplayAll()
+
+        # start test
+        self.assertRaises(test.TestingException, conn._live_migration,
+                          self.context, instance_ref, 'dest', post_method=None,
+                          recover_method=fake_recover_method,
+                          migrate_data=migrate_data)
+
     def test_rollback_live_migration_at_destination(self):
         conn = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
         with mock.patch.object(conn, "destroy") as mock_destroy:

nova/virt/libvirt/driver.py

@@ -5353,13 +5353,40 @@ class LibvirtDriver(driver.ComputeDriver):
                 old_xml_str = dom.XMLDesc(migratable_flag)
                 new_xml_str = self._correct_listen_addr(old_xml_str,
                                                         listen_addrs)
-
-                dom.migrateToURI2(CONF.libvirt.live_migration_uri % dest,
-                                  None,
-                                  new_xml_str,
-                                  logical_sum,
-                                  None,
-                                  CONF.libvirt.live_migration_bandwidth)
+                try:
+                    dom.migrateToURI2(CONF.libvirt.live_migration_uri % dest,
+                                      None,
+                                      new_xml_str,
+                                      logical_sum,
+                                      None,
+                                      CONF.libvirt.live_migration_bandwidth)
+                except libvirt.libvirtError as ex:
+                    # NOTE(mriedem): There is a bug in older versions of
+                    # libvirt where the VIR_DOMAIN_XML_MIGRATABLE flag causes
+                    # virDomainDefCheckABIStability to not compare the source
+                    # and target domain xml's correctly for the CPU model.
+                    # We try to handle that error here and attempt the legacy
+                    # migrateToURI path, which could fail if the console
+                    # addresses are not correct, but in that case we have the
+                    # _check_graphics_addresses_can_live_migrate check in place
+                    # to catch it.
+                    # TODO(mriedem): Remove this workaround when
+                    # Red Hat BZ #1141838 is closed.
+                    error_code = ex.get_error_code()
+                    if error_code == libvirt.VIR_ERR_CONFIG_UNSUPPORTED:
+                        LOG.warn(_LW('An error occurred trying to live '
+                                     'migrate. Falling back to legacy live '
+                                     'migrate flow. Error: %s'), ex,
+                                 instance=instance)
+                        self._check_graphics_addresses_can_live_migrate(
+                            listen_addrs)
+                        dom.migrateToURI(
+                            CONF.libvirt.live_migration_uri % dest,
+                            logical_sum,
+                            None,
+                            CONF.libvirt.live_migration_bandwidth)
+                    else:
+                        raise
 
         except Exception as e:
             with excutils.save_and_reraise_exception():