Adds regression test for bug LP#1944619

Related-bug: #1944619
Closes-bug: #1964472
Change-Id: Ie7e5377aea23a4fbd7ad91f245d17def6d0fb927
(cherry picked from commit 2ddb8bf)

Author: sombrafam

nova/tests/functional/regressions/test_bug_1944619.py

@@ -0,0 +1,82 @@
+# Copyright 2021, Canonical, Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import mock
+
+from nova import exception as nova_exceptions
+from nova.tests.fixtures import libvirt as fakelibvirt
+from nova.tests.functional import integrated_helpers
+from nova.tests.functional.libvirt import base
+
+
+class TestRollbackWithHWOffloadedOVS(
+    base.LibvirtMigrationMixin,
+    base.ServersTestBase,
+    integrated_helpers.InstanceHelperMixin
+):
+    """Regression test for bug LP#1944619
+
+    Assert the behaviour observed in bug LP#1944619 caused by the live
+    migration cleanup code being used to cleanup pre-live migration failures.
+    When SRIOV devices are in use on a VM, that will cause the source host to
+    try to re-attach a VIF not actually de-attached causing a failure.
+
+    The exception mocked in pre_live_migration reproduce an arbitrary error
+    that might cause the pre-live migration process to fail and
+    rollback_live_migration_at_source reproduce the device re-attach failure.
+    """
+
+    api_major_version = 'v2.1'
+    microversion = 'latest'
+    ADMIN_API = True
+
+    def setUp(self):
+        super().setUp()
+
+        self.start_compute(
+            hostname='src',
+            host_info=fakelibvirt.HostInfo(
+                cpu_nodes=1, cpu_sockets=1, cpu_cores=4, cpu_threads=1))
+        self.start_compute(
+            hostname='dest',
+            host_info=fakelibvirt.HostInfo(
+                cpu_nodes=1, cpu_sockets=1, cpu_cores=4, cpu_threads=1))
+
+        self.src = self.computes['src']
+        self.dest = self.computes['dest']
+
+    def test_rollback_pre_live_migration(self):
+        self.server = self._create_server(host='src', networks='none')
+
+        lib_path = "nova.virt.libvirt.driver.LibvirtDriver"
+        funtion_path = "pre_live_migration"
+        mock_lib_path_prelive = "%s.%s" % (lib_path, funtion_path)
+        with mock.patch(mock_lib_path_prelive,
+                        side_effect=nova_exceptions.DestinationDiskExists(
+                            path='/var/non/existent')) as mlpp:
+            funtion_path = "rollback_live_migration_at_source"
+            mock_lib_path_rollback = "%s.%s" % (lib_path, funtion_path)
+            with mock.patch(mock_lib_path_rollback) as mlpr:
+                # Live migrate the instance to another host
+                self._live_migrate(self.server,
+                                   migration_expected_state='failed',
+                                   server_expected_state='MIGRATING')
+        # FIXME(erlon): In the current behavior,
+        # rollback_live_migration_at_source is called if an error happens
+        # during the  pre_live_migration phase on the destination and therefore
+        # triggers the observed bug. rollback_live_migration_at_source should
+        # *not* be called for when errors happen during pre_live_migration
+        # phase.
+        mlpr.assert_called_once()
+        mlpp.assert_called_once()