Fixes Hyper-V driver WMI issue on 2008 R2

Trying to assign properties on default Hyper-V resource setting data
WMI objects results in an exceptions before Hyper-V 2012.
Cloning the objects before assigning them solves the issue.

A similar approach was previous already implemented and has been
incorrectly removed during a refactoring.

Co-Authored-By: Robert Tingirica <rtingirica@cloudbasesolutions.com>
Change-Id: If119154f8b4756be9f98c8acd376003c52eff44f
Closes-Bug: #1356884

nova/tests/unit/virt/hyperv/test_vmutils.py

@@ -666,3 +666,37 @@ class VMUtilsTestCase(test.NoDBTestCase):
         self._vmutils._conn.Msvm_VirtualSystemSettingData.assert_called_with(
             ['ElementName'],
             SettingType=self._vmutils._VIRTUAL_SYSTEM_CURRENT_SETTINGS)
+
+    @mock.patch.object(vmutils.VMUtils, "_clone_wmi_obj")
+    def _test_check_clone_wmi_obj(self, mock_clone_wmi_obj, clone_objects):
+        mock_obj = mock.MagicMock()
+        self._vmutils._clone_wmi_objs = clone_objects
+
+        response = self._vmutils._check_clone_wmi_obj(class_name="fakeClass",
+                                                      obj=mock_obj)
+        if not clone_objects:
+            self.assertEqual(mock_obj, response)
+        else:
+            mock_clone_wmi_obj.assert_called_once_with("fakeClass", mock_obj)
+            self.assertEqual(mock_clone_wmi_obj.return_value, response)
+
+    def test_check_clone_wmi_obj_true(self):
+        self._test_check_clone_wmi_obj(clone_objects=True)
+
+    def test_check_clone_wmi_obj_false(self):
+        self._test_check_clone_wmi_obj(clone_objects=False)
+
+    def test_clone_wmi_obj(self):
+        mock_obj = mock.MagicMock()
+        mock_value = mock.MagicMock()
+        mock_value.Value = mock.sentinel.fake_value
+        mock_obj._properties = [mock.sentinel.property]
+        mock_obj.Properties_.Item.return_value = mock_value
+
+        response = self._vmutils._clone_wmi_obj(
+            class_name="FakeClass", obj=mock_obj)
+
+        compare = self._vmutils._conn.FakeClass.new()
+        self.assertEqual(mock.sentinel.fake_value,
+                         compare.Properties_.Item().Value)
+        self.assertEqual(compare, response)

nova/virt/hyperv/vmutils.py

@@ -31,6 +31,7 @@ from nova import exception
 from nova.i18n import _, _LW
 from nova.openstack.common import log as logging
 from nova.virt.hyperv import constants
+from nova.virt.hyperv import hostutils
 
 CONF = cfg.CONF
 LOG = logging.getLogger(__name__)
@@ -99,6 +100,13 @@ class VMUtils(object):
             self._init_hyperv_wmi_conn(host)
             self._conn_cimv2 = wmi.WMI(moniker='//%s/root/cimv2' % host)
 
+        # On version of Hyper-V prior to 2012 trying to directly set properties
+        # in default setting data WMI objects results in an exception
+        self._clone_wmi_objs = False
+        if sys.platform == 'win32':
+            hostutls = hostutils.HostUtils()
+            self._clone_wmi_objs = not hostutls.check_min_windows_version(6, 2)
+
     def _init_hyperv_wmi_conn(self, host):
         self._conn = wmi.WMI(moniker='//%s/root/virtualization' % host)
 
@@ -320,19 +328,36 @@ class VMUtils(object):
         return volumes
 
     def _get_new_setting_data(self, class_name):
-        return self._conn.query("SELECT * FROM %s WHERE InstanceID "
+        obj = self._conn.query("SELECT * FROM %s WHERE InstanceID "
                                 "LIKE '%%\\Default'" % class_name)[0]
+        return self._check_clone_wmi_obj(class_name, obj)
 
     def _get_new_resource_setting_data(self, resource_sub_type,
                                        class_name=None):
         if class_name is None:
             class_name = self._RESOURCE_ALLOC_SETTING_DATA_CLASS
-        return self._conn.query("SELECT * FROM %(class_name)s "
+        obj = self._conn.query("SELECT * FROM %(class_name)s "
                                 "WHERE ResourceSubType = "
                                 "'%(res_sub_type)s' AND "
                                 "InstanceID LIKE '%%\\Default'" %
                                 {"class_name": class_name,
                                  "res_sub_type": resource_sub_type})[0]
+        return self._check_clone_wmi_obj(class_name, obj)
+
+    def _check_clone_wmi_obj(self, class_name, obj):
+        if self._clone_wmi_objs:
+            return self._clone_wmi_obj(class_name, obj)
+        else:
+            return obj
+
+    def _clone_wmi_obj(self, class_name, obj):
+        wmi_class = getattr(self._conn, class_name)
+        new_obj = wmi_class.new()
+        # Copy the properties from the original.
+        for prop in obj._properties:
+                value = obj.Properties_.Item(prop).Value
+                new_obj.Properties_.Item(prop).Value = value
+        return new_obj
 
     def attach_ide_drive(self, vm_name, path, ctrller_addr, drive_addr,
                          drive_type=constants.IDE_DISK):