Backport libvirt listDevices() fixes to yoga

nova/tests/fixtures/libvirt.py

@@ -2052,6 +2052,17 @@ def device_lookup_by_name(self, dev_name):
         return self.pci_info.get_device_by_name(dev_name)
 
     def nodeDeviceLookupByName(self, name):
+        # See bug https://bugs.launchpad.net/nova/+bug/2098892
+        # We don't test this by importing the libvirt module because the
+        # libvirt module is forbidden to be imported into our test
+        # environment. It is excluded from test-requirements.txt and we
+        # also use the ImportModulePoisonFixture in nova/test.py to prevent
+        # use of modules such as libvirt.
+        if not isinstance(name, str) and name is not None:
+            raise TypeError(
+                'virNodeDeviceLookupByName() argument 2 must be str or '
+                f'None, not {type(name)}')
+
         if name.startswith('mdev'):
             return self.mdev_info.get_device_by_name(name)
 

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

@@ -2128,6 +2128,48 @@ def test_tpool_list_all_connections(self):
             self.assertIsInstance(domain, tpool.Proxy)
             self.assertIn(domain.UUIDString(), (uuids.vm1, uuids.vm2))
 
+    def _add_fake_host_devices(self):
+        self.conn._obj.pci_info = fakelibvirt.HostPCIDevicesInfo(
+            num_pci=1, num_pfs=2, num_vfs=2, num_mdevcap=3)
+        mdevs = {
+            'mdev_4b20d080_1b54_4048_85b3_a6a62d165c01':
+                fakelibvirt.FakeMdevDevice(
+                    dev_name='mdev_4b20d080_1b54_4048_85b3_a6a62d165c01',
+                    type_id=fakelibvirt.NVIDIA_11_VGPU_TYPE,
+                    parent=fakelibvirt.MDEVCAP_DEV1_PCI_ADDR),
+        }
+        self.conn._obj.mdev_info = fakelibvirt.HostMdevDevicesInfo(
+            devices=mdevs)
+
+    def test_tpool_list_all_devices(self):
+        self._add_fake_host_devices()
+        devs = self.host.list_all_devices(
+            fakelibvirt.VIR_CONNECT_LIST_NODE_DEVICES_CAP_PCI_DEV)
+        self.assertEqual(8, len(devs))
+        for dev in devs:
+            self.assertIsInstance(dev, tpool.Proxy)
+
+    def test_tpool_list_pci_devices(self):
+        self._add_fake_host_devices()
+        dev_names = self.host.list_pci_devices()
+        self.assertEqual(8, len(dev_names))
+        for name in dev_names:
+            self.assertIsInstance(name, str)
+
+    def test_tpool_list_mdev_capable_devices(self):
+        self._add_fake_host_devices()
+        dev_names = self.host.list_mdev_capable_devices()
+        self.assertEqual(3, len(dev_names))
+        for name in dev_names:
+            self.assertIsInstance(name, str)
+
+    def test_tpool_list_mediated_devices(self):
+        self._add_fake_host_devices()
+        dev_names = self.host.list_mediated_devices()
+        self.assertEqual(1, len(dev_names))
+        for name in dev_names:
+            self.assertIsInstance(name, str)
+
 
 class LoadersTestCase(test.NoDBTestCase):
 

nova/virt/libvirt/driver.py

@@ -7959,13 +7959,27 @@ def _get_pci_passthrough_devices(self):
             dev.name(): dev for dev in
             self._host.list_all_devices(flags=dev_flags)
         }
-        net_devs = [dev for dev in devices.values() if "net" in dev.listCaps()]
+
+        # NOTE(mnaser): The listCaps() function can raise an exception if the
+        #               device disappeared while we're looping, this method
+        #               returns an empty list rather than raising an exception
+        #               which will remove the device for Nova's resource
+        #               tracker, but that is OK since the device disappeared.
+        def _safe_list_caps(dev):
+            try:
+                return dev.listCaps()
+            except libvirt.libvirtError:
+                return []
+
+        net_devs = [
+            dev for dev in devices.values() if "net" in _safe_list_caps(dev)
+        ]
         vdpa_devs = [
-            dev for dev in devices.values() if "vdpa" in dev.listCaps()
+            dev for dev in devices.values() if "vdpa" in _safe_list_caps(dev)
         ]
         pci_devs = {
             name: dev for name, dev in devices.items()
-                    if "pci" in dev.listCaps()}
+                    if "pci" in _safe_list_caps(dev)}
         pci_info = [
             self._host._get_pcidev_info(
                 name, dev, net_devs,

nova/virt/libvirt/host.py

@@ -1486,31 +1486,31 @@ def get_vdpa_device_path(
         nodedev = self.get_vdpa_nodedev_by_address(pci_address)
         return nodedev.vdpa_capability.dev_path
 
-    def list_pci_devices(self, flags=0):
+    def list_pci_devices(self, flags: int = 0) -> ty.List[str]:
         """Lookup pci devices.
 
-        :returns: a list of virNodeDevice instance
+        :returns: a list of strings, names of the virNodeDevice instances
         """
         return self._list_devices("pci", flags=flags)
 
-    def list_mdev_capable_devices(self, flags=0):
+    def list_mdev_capable_devices(self, flags: int = 0) -> ty.List[str]:
         """Lookup devices supporting mdev capabilities.
 
-        :returns: a list of virNodeDevice instance
+        :returns: a list of strings, names of the virNodeDevice instances
         """
         return self._list_devices("mdev_types", flags=flags)
 
-    def list_mediated_devices(self, flags=0):
+    def list_mediated_devices(self, flags: int = 0) -> ty.List[str]:
         """Lookup mediated devices.
 
-        :returns: a list of strings with the name of the instance
+        :returns: a list of strings, names of the virNodeDevice instances
         """
         return self._list_devices("mdev", flags=flags)
 
-    def _list_devices(self, cap, flags=0):
+    def _list_devices(self, cap, flags: int = 0) -> ty.List[str]:
         """Lookup devices.
 
-        :returns: a list of virNodeDevice instance
+        :returns: a list of strings, names of the virNodeDevice instances
         """
         try:
             return self.get_connection().listDevices(cap, flags)
@@ -1533,7 +1533,10 @@ def list_all_devices(
         :returns: a list of virNodeDevice xml strings.
         """
         try:
-            return self.get_connection().listAllDevices(flags) or []
+            alldevs = [
+                self._wrap_libvirt_proxy(dev)
+                for dev in self.get_connection().listAllDevices(flags)] or []
+            return alldevs
         except libvirt.libvirtError as ex:
             LOG.warning(ex)
             return []

releasenotes/notes/unproxied-libvirt-list-devices-7cd218c1a33535c9.yaml

@@ -0,0 +1,11 @@
+fixes:
+  - |
+    `Bug #2091033`_: Fixed calls to libvirt ``listDevices()`` and
+    ``listAllDevices()`` from potentially blocking all other greenthreads
+    in ``nova-compute``. Under certain circumstances, it was possible for
+    the ``nova-compute`` service to freeze with all other greenthreads
+    blocked and unable to perform any other activities including logging.
+    This issue has been fixed by wrapping the libvirt ``listDevices()``
+    and ``listAllDevices()`` calls with ``eventlet.tpool.Proxy``.
+
+    .. _Bug #2091033: https://bugs.launchpad.net/nova/+bug/2091033