Ignore hw_vif_type for direct, direct-physical vNIC types

As part of the fix for bug #1789074, we stopped setting the VIF model to
virtio for a vif_type of 'direct' or 'direct-physical'. However, if
users configured the 'hw_vif_type' image metadata property, the VIF
model would be unconditionally set to whatever the user provided. This
would result in bug #1789074 recurring. Given that the model attribute
is unnecessary for these vNIC types, we can resolve this issue by
simply ignoring the image metadata property when configuring such VIFs.

Change-Id: I3bf5587c3a49c807bb14533dbbea8f72dca2f02b
Signed-off-by: Stephen Finucane <[email protected]>
Closes-bug: #1797146
(cherry picked from commit a235451)
(cherry picked from commit d78310e)

Author: stephenfin

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

@@ -847,8 +847,10 @@ def test_model_with_osinfo(self, mock_set):
         mock_set.assert_called_once_with(mock.ANY, 'ca:fe:de:ad:be:ef',
                                          'virtio', None, None, None)
 
-    @mock.patch.object(vif.designer, 'set_vif_guest_frontend_config')
-    def test_model_sriov_direct_multi_queue_not_set(self, mock_set):
+    @mock.patch.object(vif.designer, 'set_vif_guest_frontend_config',
+                       wraps=vif.designer.set_vif_guest_frontend_config)
+    def test_model_sriov_direct(self, mock_set):
+        """Direct attach vNICs shouldn't retrieve info from image_meta."""
         self.flags(use_virtio_for_bridges=True,
                    virt_type='kvm',
                    group='libvirt')
@@ -857,15 +859,16 @@ def test_model_sriov_direct_multi_queue_not_set(self, mock_set):
             fakelibosinfo))
         d = vif.LibvirtGenericVIFDriver()
         hostimpl = host.Host("qemu:///system")
-        image_meta = {'properties': {'os_name': 'fedora22'}}
-        image_meta = objects.ImageMeta.from_dict(image_meta)
+        image_meta = objects.ImageMeta.from_dict(
+            {'properties': {'hw_vif_model': 'virtio'}})
         conf = d.get_base_config(None, 'ca:fe:de:ad:be:ef', image_meta,
                                  None, 'kvm', network_model.VNIC_TYPE_DIRECT,
                                  hostimpl)
         mock_set.assert_called_once_with(mock.ANY, 'ca:fe:de:ad:be:ef',
                                          None, None, None, None)
         self.assertIsNone(conf.vhost_queues)
         self.assertIsNone(conf.driver_name)
+        self.assertIsNone(conf.model)
 
     def _test_model_qemu(self, *vif_objs, **kw):
         libvirt_version = kw.get('libvirt_version')

nova/virt/libvirt/vif.py

@@ -128,21 +128,25 @@ def get_base_config(self, instance, mac, image_meta,
         model = None
         driver = None
         vhost_queues = None
+        rx_queue_size = None
+
+        # NOTE(stephenfin): Skip most things here as only apply to virtio
+        # devices
+        if vnic_type in network_model.VNIC_TYPES_DIRECT_PASSTHROUGH:
+            designer.set_vif_guest_frontend_config(
+                conf, mac, model, driver, vhost_queues, rx_queue_size)
+            return conf
 
         # If the user has specified a 'vif_model' against the
         # image then honour that model
         if image_meta:
             model = osinfo.HardwareProperties(image_meta).network_model
 
-        # Note(moshele): Skip passthough vnic_types as they don't support
-        # virtio model.
-        if vnic_type not in network_model.VNIC_TYPES_DIRECT_PASSTHROUGH:
-            # Else if the virt type is KVM/QEMU/VZ(Parallels), then use virtio
-            # according to the global config parameter
-            if (model is None and
-                virt_type in ('kvm', 'qemu', 'parallels') and
-                        CONF.libvirt.use_virtio_for_bridges):
-                model = network_model.VIF_MODEL_VIRTIO
+        # If the virt type is KVM/QEMU/VZ(Parallels), then use virtio according
+        # to the global config parameter
+        if (model is None and virt_type in ('kvm', 'qemu', 'parallels') and
+                CONF.libvirt.use_virtio_for_bridges):
+            model = network_model.VIF_MODEL_VIRTIO
 
         # Workaround libvirt bug, where it mistakenly
         # enables vhost mode, even for non-KVM guests
@@ -167,7 +171,6 @@ def get_base_config(self, instance, mac, image_meta,
             # use vhost and not None.
             driver = vhost_drv or driver
 
-        rx_queue_size = None
         # Note(moshele): rx_queue_size is support only for virtio model
         if model == network_model.VIF_MODEL_VIRTIO:
             if driver == 'vhost' or driver is None: