Merge "libvirt: Add a default VirtIO-RNG device to guests"

nova/objects/fields.py

@@ -480,6 +480,20 @@ class OSType(BaseNovaEnum):
 
 class RNGModel(BaseNovaEnum):
 
+    # NOTE(kchamart): Along with "virtio", we may need to extend this (if a
+    # good reason shows up) to allow two more values for VirtIO
+    # transitional and non-transitional devices (available since libvirt
+    # 5.2.0):
+    #
+    #   - virtio-transitional
+    #   - virtio-nontransitional
+    #
+    # This allows one to choose whether you want to have compatibility
+    # with older guest operating systems.  The value you select will in
+    # turn decide the kind of PCI topology the guest will get.
+    #
+    # Details:
+    # https://libvirt.org/formatdomain.html#elementsVirtioTransitional
     VIRTIO = "virtio"
 
     ALL = (VIRTIO,)

nova/objects/image_meta.py

@@ -359,6 +359,12 @@ class ImageMetaProps(base.NovaObject):
         'hw_rescue_device': fields.BlockDeviceTypeField(),
 
         # name of the RNG device type eg virtio
+        # NOTE(kchamart): Although this is currently not used anymore,
+        # we should not remove / deprecate it yet, as we are likely to
+        # extend this field to allow two more values to support "VirtIO
+        # transitional/non-transitional devices" (refer to the note in
+        # RNGModel() class in nova/objects/fields.py), and thus expose
+        # to the user again.
         'hw_rng_model': fields.RNGModelField(),
 
         # boolean 'true' or 'false' to enable HPET

nova/tests/unit/virt/libvirt/test_driver.py

@@ -2447,7 +2447,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertEqual(cfg.os_type, fields.VMMode.HVM)
         self.assertEqual(cfg.os_boot_dev, ["hd"])
         self.assertIsNone(cfg.os_root)
-        self.assertEqual(len(cfg.devices), 9)
+        self.assertEqual(len(cfg.devices), 10)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -2465,6 +2465,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[8],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[9],
                               vconfig.LibvirtConfigMemoryBalloon)
         self.assertEqual(len(cfg.metadata), 1)
         self.assertIsInstance(cfg.metadata[0],
@@ -4472,7 +4474,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertEqual(cfg.os_type, fields.VMMode.HVM)
         self.assertEqual(cfg.os_boot_dev, ["hd"])
         self.assertIsNone(cfg.os_root)
-        self.assertEqual(len(cfg.devices), 9)
+        self.assertEqual(len(cfg.devices), 10)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -4490,6 +4492,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[8],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[9],
                               vconfig.LibvirtConfigMemoryBalloon)
 
     def test_get_guest_config_with_root_device_name(self):
@@ -4940,7 +4944,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         cfg = self._get_guest_config_with_graphics()
 
-        self.assertEqual(len(cfg.devices), 6)
+        self.assertEqual(len(cfg.devices), 7)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -4952,6 +4956,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[4],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[5],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[6],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual(cfg.devices[3].type, 'vnc')
@@ -4967,7 +4973,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         cfg = self._get_guest_config_with_graphics()
 
-        self.assertEqual(len(cfg.devices), 7)
+        self.assertEqual(len(cfg.devices), 8)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -4981,6 +4987,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[5],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[6],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual(cfg.devices[3].type, "tablet")
@@ -4999,7 +5007,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         cfg = self._get_guest_config_with_graphics()
 
-        self.assertEqual(len(cfg.devices), 7)
+        self.assertEqual(len(cfg.devices), 8)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5013,6 +5021,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[5],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[6],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual(cfg.devices[3].type, 'tablet')
@@ -5034,7 +5044,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         expect = {"ppc": "vga", "ppc64": "vga",
                   "ppc64le": "vga", "aarch64": "virtio"}
         video_type = expect.get(blockinfo.libvirt_utils.get_arch({}), "qxl")
-        self.assertEqual(len(cfg.devices), 7)
+        self.assertEqual(len(cfg.devices), 8)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5048,6 +5058,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[5],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[6],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual(cfg.devices[3].target_name, "com.redhat.spice.0")
@@ -5167,7 +5179,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         cfg = drvr._get_guest_config(instance_ref, [],
                                      image_meta, disk_info)
-        self.assertEqual(7, len(cfg.devices))
+        self.assertEqual(8, len(cfg.devices))
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5181,6 +5193,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[5],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[6],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual("tcp", cfg.devices[2].type)
@@ -5201,7 +5215,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         cfg = drvr._get_guest_config(instance_ref, [],
                                      image_meta, disk_info)
-        self.assertEqual(9, len(cfg.devices))
+        self.assertEqual(10, len(cfg.devices))
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5219,6 +5233,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[8],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[9],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual("tcp", cfg.devices[2].type)
@@ -5259,7 +5275,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                                             image_meta)
         cfg = drvr._get_guest_config(instance_ref, [], image_meta,
                                      disk_info)
-        self.assertEqual(9, len(cfg.devices), cfg.devices)
+        self.assertEqual(10, len(cfg.devices), cfg.devices)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5277,6 +5293,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[8],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[9],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual("tcp", cfg.devices[2].type)
@@ -5632,7 +5650,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                                             image_meta)
         cfg = drvr._get_guest_config(instance_ref, [],
                                      image_meta, disk_info)
-        self.assertEqual(len(cfg.devices), 9)
+        self.assertEqual(len(cfg.devices), 10)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5650,6 +5668,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[8],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[9],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual(cfg.devices[3].type, "tablet")
@@ -5672,7 +5692,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                                             image_meta)
 
         cfg = drvr._get_guest_config(instance_ref, [], image_meta, disk_info)
-        self.assertEqual(len(cfg.devices), 8)
+        self.assertEqual(len(cfg.devices), 9)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5686,11 +5706,13 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[5],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[6],
-                              vconfig.LibvirtConfigGuestWatchdog)
+                              vconfig.LibvirtConfigGuestRng)
         self.assertIsInstance(cfg.devices[7],
+                              vconfig.LibvirtConfigGuestWatchdog)
+        self.assertIsInstance(cfg.devices[8],
                               vconfig.LibvirtConfigMemoryBalloon)
 
-        self.assertEqual("none", cfg.devices[6].action)
+        self.assertEqual("none", cfg.devices[7].action)
 
     def _test_get_guest_usb_tablet(self, vnc_enabled, spice_enabled, os_type,
                                    agent_enabled=False, image_meta=None):
@@ -5824,7 +5846,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         cfg = drvr._get_guest_config(instance_ref, [],
                                      image_meta, disk_info)
 
-        self.assertEqual(8, len(cfg.devices))
+        self.assertEqual(9, len(cfg.devices))
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5838,11 +5860,13 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[5],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[6],
-                              vconfig.LibvirtConfigGuestWatchdog)
+                              vconfig.LibvirtConfigGuestRng)
         self.assertIsInstance(cfg.devices[7],
+                              vconfig.LibvirtConfigGuestWatchdog)
+        self.assertIsInstance(cfg.devices[8],
                               vconfig.LibvirtConfigMemoryBalloon)
 
-        self.assertEqual("none", cfg.devices[6].action)
+        self.assertEqual("none", cfg.devices[7].action)
 
     def test_get_guest_config_with_watchdog_overrides_flavor(self):
         self.flags(virt_type='kvm', group='libvirt')
@@ -5862,7 +5886,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         cfg = drvr._get_guest_config(instance_ref, [],
                                      image_meta, disk_info)
 
-        self.assertEqual(8, len(cfg.devices))
+        self.assertEqual(9, len(cfg.devices))
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5876,11 +5900,12 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[5],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[6],
-                              vconfig.LibvirtConfigGuestWatchdog)
+                              vconfig.LibvirtConfigGuestRng)
         self.assertIsInstance(cfg.devices[7],
+                              vconfig.LibvirtConfigGuestWatchdog)
+        self.assertIsInstance(cfg.devices[8],
                               vconfig.LibvirtConfigMemoryBalloon)
-
-        self.assertEqual("pause", cfg.devices[6].action)
+        self.assertEqual("pause", cfg.devices[7].action)
 
     def test_get_guest_config_with_video_driver_image_meta(self):
         self.flags(virt_type='kvm', group='libvirt')
@@ -5891,43 +5916,45 @@ class LibvirtConnTestCase(test.NoDBTestCase,
             "disk_format": "raw",
             "properties": {"hw_video_model": "vmvga"}})
 
-        disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
-                                            instance_ref,
-                                            image_meta)
-        cfg = drvr._get_guest_config(instance_ref, [], image_meta, disk_info)
-        self.assertEqual(len(cfg.devices), 7)
-        self.assertIsInstance(cfg.devices[0],
-                              vconfig.LibvirtConfigGuestDisk)
-        self.assertIsInstance(cfg.devices[1],
-                              vconfig.LibvirtConfigGuestDisk)
-        self.assertIsInstance(cfg.devices[2],
-                              vconfig.LibvirtConfigGuestSerial)
-        self.assertIsInstance(cfg.devices[3],
-                              vconfig.LibvirtConfigGuestInput)
-        self.assertIsInstance(cfg.devices[4],
-                              vconfig.LibvirtConfigGuestGraphics)
-        self.assertIsInstance(cfg.devices[5],
-                              vconfig.LibvirtConfigGuestVideo)
-        self.assertIsInstance(cfg.devices[6],
-                              vconfig.LibvirtConfigMemoryBalloon)
-
-        self.assertEqual(cfg.devices[4].type, "vnc")
-        self.assertEqual(cfg.devices[5].type, "vmvga")
-
-    def test_get_guest_config_with_qga_through_image_meta(self):
-        self.flags(virt_type='kvm', group='libvirt')
-
-        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
-        instance_ref = objects.Instance(**self.test_instance)
-        image_meta = objects.ImageMeta.from_dict({
-            "disk_format": "raw",
-            "properties": {"hw_qemu_guest_agent": "yes"}})
-
         disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
                                             instance_ref,
                                             image_meta)
         cfg = drvr._get_guest_config(instance_ref, [], image_meta, disk_info)
         self.assertEqual(len(cfg.devices), 8)
+        self.assertIsInstance(cfg.devices[0],
+                              vconfig.LibvirtConfigGuestDisk)
+        self.assertIsInstance(cfg.devices[1],
+                              vconfig.LibvirtConfigGuestDisk)
+        self.assertIsInstance(cfg.devices[2],
+                              vconfig.LibvirtConfigGuestSerial)
+        self.assertIsInstance(cfg.devices[3],
+                              vconfig.LibvirtConfigGuestInput)
+        self.assertIsInstance(cfg.devices[4],
+                              vconfig.LibvirtConfigGuestGraphics)
+        self.assertIsInstance(cfg.devices[5],
+                              vconfig.LibvirtConfigGuestVideo)
+        self.assertIsInstance(cfg.devices[6],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[7],
+                              vconfig.LibvirtConfigMemoryBalloon)
+
+        self.assertEqual(cfg.devices[4].type, "vnc")
+        self.assertEqual(cfg.devices[5].type, "vmvga")
+
+    def test_get_guest_config_with_qga_through_image_meta(self):
+        self.flags(virt_type='kvm', group='libvirt')
+
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
+        instance_ref = objects.Instance(**self.test_instance)
+        image_meta = objects.ImageMeta.from_dict({
+            "disk_format": "raw",
+            "properties": {"hw_qemu_guest_agent": "yes"}})
+
+        disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
+                                            instance_ref,
+                                            image_meta)
+        cfg = drvr._get_guest_config(instance_ref, [], image_meta, disk_info)
+        self.assertEqual(len(cfg.devices), 9)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -5943,6 +5970,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[6],
                               vconfig.LibvirtConfigGuestChannel)
         self.assertIsInstance(cfg.devices[7],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[8],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual(cfg.devices[3].type, "tablet")
@@ -5989,7 +6018,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         cfg = drvr._get_guest_config(instance_ref, [],
                                      image_meta, disk_info)
-        self.assertEqual(len(cfg.devices), 7)
+        self.assertEqual(len(cfg.devices), 8)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -6003,6 +6032,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[5],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[6],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual(cfg.devices[4].type, "spice")
@@ -6172,7 +6203,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                                             instance_ref,
                                             image_meta)
         cfg = drvr._get_guest_config(instance_ref, [], image_meta, disk_info)
-        self.assertEqual(len(cfg.devices), 7)
+        self.assertEqual(len(cfg.devices), 8)
         self.assertIsInstance(cfg.devices[0],
                               vconfig.LibvirtConfigGuestDisk)
         self.assertIsInstance(cfg.devices[1],
@@ -6186,6 +6217,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         self.assertIsInstance(cfg.devices[5],
                               vconfig.LibvirtConfigGuestVideo)
         self.assertIsInstance(cfg.devices[6],
+                              vconfig.LibvirtConfigGuestRng)
+        self.assertIsInstance(cfg.devices[7],
                               vconfig.LibvirtConfigMemoryBalloon)
 
         self.assertEqual(cfg.devices[3].type, "tablet")
@@ -6197,10 +6230,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
         instance_ref = objects.Instance(**self.test_instance)
-        instance_ref.flavor.extra_specs = {'hw_rng:allowed': 'True'}
         image_meta = objects.ImageMeta.from_dict({
-            "disk_format": "raw",
-            "properties": {"hw_rng_model": "virtio"}})
+            "disk_format": "raw"})
 
         disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
                                             instance_ref,
@@ -6235,9 +6266,9 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
         instance_ref = objects.Instance(**self.test_instance)
+        instance_ref.flavor.extra_specs = {'hw_rng:allowed': 'False'}
         image_meta = objects.ImageMeta.from_dict({
-            "disk_format": "raw",
-            "properties": {"hw_rng_model": "virtio"}})
+            "disk_format": "raw"})
 
         disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
                                             instance_ref,
@@ -6265,12 +6296,10 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
         instance_ref = objects.Instance(**self.test_instance)
-        instance_ref.flavor.extra_specs = {'hw_rng:allowed': 'True',
-                                           'hw_rng:rate_bytes': '1024',
+        instance_ref.flavor.extra_specs = {'hw_rng:rate_bytes': '1024',
                                            'hw_rng:rate_period': '2'}
         image_meta = objects.ImageMeta.from_dict({
-            "disk_format": "raw",
-            "properties": {"hw_rng_model": "virtio"}})
+            "disk_format": "raw"})
 
         disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
                                             instance_ref,
@@ -6310,10 +6339,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
         instance_ref = objects.Instance(**self.test_instance)
-        instance_ref.flavor.extra_specs = {'hw_rng:allowed': 'True'}
         image_meta = objects.ImageMeta.from_dict({
-            "disk_format": "raw",
-            "properties": {"hw_rng_model": "virtio"}})
+            "disk_format": "raw"})
 
         disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
                                             instance_ref,
@@ -6352,10 +6379,8 @@ class LibvirtConnTestCase(test.NoDBTestCase,
 
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
         instance_ref = objects.Instance(**self.test_instance)
-        instance_ref.flavor.extra_specs = {'hw_rng:allowed': 'True'}
         image_meta = objects.ImageMeta.from_dict({
-            "disk_format": "raw",
-            "properties": {"hw_rng_model": "virtio"}})
+            "disk_format": "raw"})
 
         disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
                                             instance_ref,
@@ -7013,8 +7038,9 @@ class LibvirtConnTestCase(test.NoDBTestCase,
                                      _fake_network_info(self),
                                      image_meta, disk_info)
         self.assertTrue(mock_path_exists.called)
-        mock_path_exists.assert_any_call(
-            libvirt_driver.DEFAULT_UEFI_LOADER_PATH['aarch64'][0])
+        expected = mock.call(libvirt_driver.
+                             DEFAULT_UEFI_LOADER_PATH['aarch64'][0])
+        self.assertIn(expected, mock_path_exists.mock_calls)
         self.assertEqual(cfg.os_mach_type, "virt")
 
         num_ports = 0
@@ -7059,8 +7085,9 @@ class LibvirtConnTestCase(test.NoDBTestCase,
         cfg = self._get_guest_config_with_graphics()
 
         self.assertTrue(mock_path_exists.called)
-        mock_path_exists.assert_any_call(
-            libvirt_driver.DEFAULT_UEFI_LOADER_PATH['aarch64'][0])
+        expected = mock.call(libvirt_driver.
+                             DEFAULT_UEFI_LOADER_PATH['aarch64'][0])
+        self.assertIn(expected, mock_path_exists.mock_calls)
         self.assertEqual(cfg.os_mach_type, "virt")
 
         usbhost_exists = False

nova/virt/libvirt/driver.py

@@ -5076,21 +5076,23 @@ class LibvirtDriver(driver.ComputeDriver):
         guest.add_device(qga)
 
     def _add_rng_device(self, guest, flavor, image_meta):
-        rng_is_virtio = image_meta.properties.get('hw_rng_model') == 'virtio'
-        rng_allowed_str = flavor.extra_specs.get('hw_rng:allowed', '')
+        rng_allowed_str = flavor.extra_specs.get('hw_rng:allowed', 'True')
         rng_allowed = strutils.bool_from_string(rng_allowed_str)
-        if rng_is_virtio and rng_allowed:
-            rng_device = vconfig.LibvirtConfigGuestRng()
-            rate_bytes = flavor.extra_specs.get('hw_rng:rate_bytes', 0)
-            period = flavor.extra_specs.get('hw_rng:rate_period', 0)
-            if rate_bytes:
-                rng_device.rate_bytes = int(rate_bytes)
-                rng_device.rate_period = int(period)
-            rng_path = CONF.libvirt.rng_dev_path
-            if (rng_path and not os.path.exists(rng_path)):
-                raise exception.RngDeviceNotExist(path=rng_path)
-            rng_device.backend = rng_path
-            guest.add_device(rng_device)
+
+        if not rng_allowed:
+            return
+
+        rng_device = vconfig.LibvirtConfigGuestRng()
+        rate_bytes = flavor.extra_specs.get('hw_rng:rate_bytes', 0)
+        period = flavor.extra_specs.get('hw_rng:rate_period', 0)
+        if rate_bytes:
+            rng_device.rate_bytes = int(rate_bytes)
+            rng_device.rate_period = int(period)
+        rng_path = CONF.libvirt.rng_dev_path
+        if (rng_path and not os.path.exists(rng_path)):
+            raise exception.RngDeviceNotExist(path=rng_path)
+        rng_device.backend = rng_path
+        guest.add_device(rng_device)
 
     def _add_virtio_serial_controller(self, guest, instance):
         virtio_controller = vconfig.LibvirtConfigGuestController()

releasenotes/notes/virtio-rng-by-default-9cc1366ed1634129.yaml

@@ -0,0 +1,9 @@
+---
+features:
+  - |
+    When using the libvirt driver, Nova instances will now get a
+    VirtIO-RNG (Random Number Generator) device by default.  This is to
+    ensure guests are not starved of entropy during boot time.  In case
+    you want to *disallow* setting an RNG device for some reason, it can
+    be done by setting the flavor Extra Spec property ``hw_rng:allowed``
+    to ``False``.