Fix virsh domifstat to get vhostuser vif statistics

When a DPDK VM attaches an interface, libvirt can not automatically
generate "<target dev='vhuXXX'/>" in XML file, which causes virsh
domifstat query to fail.

Change-Id: Id4e5b52af521b5f3a206e87bf024fd1e47fc4824
Closes-Bug: #1899431
(cherry picked from commit 4a4f126)

Author: zhanghao

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

@@ -207,6 +207,19 @@ def test_set_vif_host_backend_vhostuser_config_rx_queue_size(self):
         self.assertEqual(512, conf.vhost_rx_queue_size)
         self.assertIsNone(conf.vhost_tx_queue_size)
 
+    def test_set_vif_host_backend_vhostuser_config_tapname(self):
+        conf = config.LibvirtConfigGuestInterface()
+        designer.set_vif_host_backend_vhostuser_config(conf, 'fake-mode',
+                                                       'fake-path', None, None,
+                                                       'fake-tap')
+        self.assertEqual('vhostuser', conf.net_type)
+        self.assertEqual('unix', conf.vhostuser_type)
+        self.assertEqual('fake-mode', conf.vhostuser_mode)
+        self.assertEqual('fake-path', conf.vhostuser_path)
+        self.assertIsNone(conf.vhost_rx_queue_size)
+        self.assertIsNone(conf.vhost_tx_queue_size)
+        self.assertEqual('fake-tap', conf.target_dev)
+
     def test_set_vif_mtu_config(self):
         conf = config.LibvirtConfigGuestInterface()
         designer.set_vif_mtu_config(conf, 9000)

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

@@ -556,6 +556,12 @@ def _assertPciEqual(self, node, vif, type=None):
         pci_slot_want = vif['profile']['pci_slot']
         self.assertEqual(pci_slot, pci_slot_want)
 
+    def _assertQueueSizeEquals(self, node, rx_want, tx_want):
+        rx_queue_size = node.find("driver").get("rx_queue_size")
+        tx_queue_size = node.find("driver").get("tx_queue_size")
+        self.assertEqual(rx_queue_size, rx_want)
+        self.assertEqual(tx_queue_size, tx_want)
+
     def _assertXmlEqual(self, expectedXmlstr, actualXmlstr):
         if not isinstance(actualXmlstr, six.string_types):
             actualXmlstr = etree.tostring(actualXmlstr, encoding='unicode',
@@ -1296,24 +1302,8 @@ def test_vhostuser_driver_queue_sizes(self):
         self.flags(tx_queue_size=1024, group='libvirt')
         d = vif.LibvirtGenericVIFDriver()
         xml = self._get_instance_xml(d, self.vif_vhostuser)
-        self._assertXmlEqual("""
-         <domain type="qemu">
-          <uuid>fake-uuid</uuid>
-          <name>fake-name</name>
-          <memory>102400</memory>
-          <vcpu>4</vcpu>
-          <os>
-           <type>None</type>
-          </os>
-          <devices>
-           <interface type="vhostuser">
-            <mac address="ca:fe:de:ad:be:ef"/>
-            <model type="virtio"/>
-            <driver rx_queue_size="512" tx_queue_size="1024"/>
-            <source mode="client" path="/tmp/vif-xxx-yyy-zzz" type="unix"/>
-           </interface>
-          </devices>
-        </domain>""", xml)
+        node = self._get_node(xml)
+        self._assertQueueSizeEquals(node, "512", "1024")
 
     def test_vhostuser_driver_no_path(self):
         d = vif.LibvirtGenericVIFDriver()
@@ -1554,6 +1544,7 @@ def test_config_os_vif_vhostuser(self):
              <model type="virtio"/>
              <source mode="client"
               path="/var/run/openvswitch/vhudc065497-3c" type="unix"/>
+             <target dev="vhudc065497-3c"/>
             </interface>"""
 
         self._test_config_os_vif(os_vif_type, vif_type, expected_xml)
@@ -1591,6 +1582,7 @@ def test_config_os_vif_agilio_ovs_forwarder(self):
              <model type="virtio"/>
              <source mode="client"
               path="/var/run/openvswitch/vhudc065497-3c" type="unix"/>
+             <target dev="nicdc065497-3c"/>
             </interface>"""
 
         self._test_config_os_vif(os_vif_type, vif_type, expected_xml)

nova/virt/libvirt/designer.py

@@ -133,7 +133,7 @@ def set_vif_host_backend_direct_config(conf, devname, mode="passthrough"):
 
 
 def set_vif_host_backend_vhostuser_config(conf, mode, path, rx_queue_size,
-                                          tx_queue_size):
+                                          tx_queue_size, tapname=None):
     """Populate a LibvirtConfigGuestInterface instance
     with host backend details for vhostuser socket.
 
@@ -147,6 +147,8 @@ def set_vif_host_backend_vhostuser_config(conf, mode, path, rx_queue_size,
         conf.vhost_rx_queue_size = rx_queue_size
     if tx_queue_size:
         conf.vhost_tx_queue_size = tx_queue_size
+    if tapname:
+        conf.target_dev = tapname
 
 
 def set_vif_mtu_config(conf, mtu):

nova/virt/libvirt/vif.py

@@ -462,7 +462,7 @@ def _set_config_VIFVHostUser(self, instance, vif, conf):
 
         designer.set_vif_host_backend_vhostuser_config(
             conf, vif.mode, vif.path, CONF.libvirt.rx_queue_size,
-            CONF.libvirt.tx_queue_size)
+            CONF.libvirt.tx_queue_size, vif.vif_name)
 
     def _set_config_VIFHostDevice(self, instance, vif, conf):
         if vif.dev_type == osv_fields.VIFHostDeviceDevType.ETHERNET: