Merge "Handle mdev devices in libvirt 7.7+" into stable/yoga

6 files changed, 97 insertions, 27 deletions

diff --git a/nova/tests/functional/regressions/test_bug_1951656.py b/nova/tests/functional/regressions/test_bug_1951656.py
index 9aad191072..d705ff6fe3 100644
--- a/nova/tests/functional/regressions/test_bug_1951656.py
+++ b/nova/tests/functional/regressions/test_bug_1951656.py
@@ -63,21 +63,11 @@ class VGPUTestsLibvirt7_7(test_vgpu.VGPUTestBase):
             flavor_id=self.flavor, host=self.compute1.host,
             networks='auto', expected_state='ACTIVE')
 
-        # TODO(sbauza): Modify this once bug #1851656 is fixed.
-        # mdev_name2uuid() raises a badly formed hexadecimal UUID string error
-        self.assertRaises(ValueError,
-                          self.assert_mdev_usage,
-                          self.compute1, expected_amount=1)
-
-        # Now, the problem is that we can't create new instances with VGPUs
-        # from this host.
-        server = self._create_server(
+        self.assert_mdev_usage(self.compute1, expected_amount=1)
+
+        self._create_server(
             image_uuid='155d900f-4e14-4e4c-a73d-069cbf4541e6',
             flavor_id=self.flavor, host=self.compute1.host,
-            networks='auto', expected_state='ERROR')
-        # The error is due to a bad mdev name parsing
-        self.assertIn('fault', server)
-        # since we only have one host, we have a RescheduledException as this
-        # service was creating an exception and we can't use another one.
-        self.assertIn('Exceeded maximum number of retries',
-                      server['fault']['message'])
+            networks='auto', expected_state='ACTIVE')
+
+        self.assert_mdev_usage(self.compute1, expected_amount=2)
diff --git a/nova/tests/unit/virt/libvirt/test_config.py b/nova/tests/unit/virt/libvirt/test_config.py
index 396edfd024..c7577745ab 100644
--- a/nova/tests/unit/virt/libvirt/test_config.py
+++ b/nova/tests/unit/virt/libvirt/test_config.py
@@ -3135,6 +3135,32 @@ class LibvirtConfigNodeDeviceTest(LibvirtConfigBaseTest):
                               config.LibvirtConfigNodeDeviceMdevInformation)
         self.assertEqual("nvidia-11", obj.mdev_information.type)
         self.assertEqual(12, obj.mdev_information.iommu_group)
+        self.assertIsNone(obj.mdev_information.uuid)
+
+    def test_config_mdev_device_uuid(self):
+        xmlin = """
+        <device>
+          <name>mdev_b2107403_110c_45b0_af87_32cc91597b8a_0000_41_00_0</name>
+          <path>/sys/devices/pci0000:40/0000:40:03.1/0000:41:00.0/b2107403-110c-45b0-af87-32cc91597b8a</path>
+          <parent>pci_0000_41_00_0</parent>
+          <driver>
+            <name>vfio_mdev</name>
+          </driver>
+          <capability type='mdev'>
+            <type id='nvidia-442'/>
+            <uuid>b2107403-110c-45b0-af87-32cc91597b8a</uuid>
+            <iommuGroup number='57'/>
+          </capability>
+        </device>"""
+
+        obj = config.LibvirtConfigNodeDevice()
+        obj.parse_str(xmlin)
+        self.assertIsInstance(obj.mdev_information,
+                              config.LibvirtConfigNodeDeviceMdevInformation)
+        self.assertEqual("nvidia-442", obj.mdev_information.type)
+        self.assertEqual(57, obj.mdev_information.iommu_group)
+        self.assertEqual("b2107403-110c-45b0-af87-32cc91597b8a",
+                         obj.mdev_information.uuid)
 
     def test_config_vdpa_device(self):
         xmlin = """
diff --git a/nova/virt/libvirt/config.py b/nova/virt/libvirt/config.py
index 1a81be3ade..47e92e3ca9 100644
--- a/nova/virt/libvirt/config.py
+++ b/nova/virt/libvirt/config.py
@@ -3299,6 +3299,7 @@ class LibvirtConfigNodeDeviceMdevInformation(LibvirtConfigObject):
                                         root_name="capability", **kwargs)
         self.type = None
         self.iommu_group = None
+        self.uuid = None
 
     def parse_dom(self, xmldoc):
         super(LibvirtConfigNodeDeviceMdevInformation,
@@ -3308,6 +3309,8 @@ class LibvirtConfigNodeDeviceMdevInformation(LibvirtConfigObject):
                 self.type = c.get('id')
             if c.tag == "iommuGroup":
                 self.iommu_group = int(c.get('number'))
+            if c.tag == "uuid":
+                self.uuid = c.text
 
 
 class LibvirtConfigNodeDeviceVpdCap(LibvirtConfigObject):
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index cc5e4b5da5..e792655a7d 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -8019,15 +8019,52 @@ class LibvirtDriver(driver.ComputeDriver):
 
     def _get_mediated_device_information(self, devname):
         """Returns a dict of a mediated device."""
-        virtdev = self._host.device_lookup_by_name(devname)
+        # LP #1951656 - In Libvirt 7.7, the mdev name now includes the PCI
+        # address of the parent device (e.g. mdev_<uuid>_<pci_address>) due to
+        # the mdevctl allowing for multiple mediated devs having the same UUID
+        # defined (only one can be active at a time). Since the guest
+        # information doesn't have the parent ID, try to lookup which
+        # mediated device is available that matches the UUID. If multiple
+        # devices are found that match the UUID, then this is an error
+        # condition.
+        try:
+            virtdev = self._host.device_lookup_by_name(devname)
+        except libvirt.libvirtError as ex:
+            if ex.get_error_code() != libvirt.VIR_ERR_NO_NODE_DEVICE:
+                raise
+            mdevs = [dev for dev in self._host.list_mediated_devices()
+                     if dev.startswith(devname)]
+            # If no matching devices are found, simply raise the original
+            # exception indicating that no devices are found.
+            if not mdevs:
+                raise
+            elif len(mdevs) > 1:
+                msg = ("The mediated device name %(devname)s refers to a UUID "
+                       "that is present in multiple libvirt mediated devices. "
+                       "Matching libvirt mediated devices are %(devices)s. "
+                       "Mediated device UUIDs must be unique for Nova." %
+                       {'devname': devname,
+                        'devices': ', '.join(mdevs)})
+                raise exception.InvalidLibvirtMdevConfig(reason=msg)
+
+            LOG.debug('Found requested device %s as %s. Using that.',
+                      devname, mdevs[0])
+            virtdev = self._host.device_lookup_by_name(mdevs[0])
         xmlstr = virtdev.XMLDesc(0)
         cfgdev = vconfig.LibvirtConfigNodeDevice()
         cfgdev.parse_str(xmlstr)
+        # Starting with Libvirt 7.3, the uuid information is available in the
+        # node device information. If its there, use that. Otherwise,
+        # fall back to the previous behavior of parsing the uuid from the
+        # devname.
+        if cfgdev.mdev_information.uuid:
+            mdev_uuid = cfgdev.mdev_information.uuid
+        else:
+            mdev_uuid = libvirt_utils.mdev_name2uuid(cfgdev.name)
 
         device = {
             "dev_id": cfgdev.name,
-            # name is like mdev_00ead764_fdc0_46b6_8db9_2963f5c815b4
-            "uuid": libvirt_utils.mdev_name2uuid(cfgdev.name),
+            "uuid": mdev_uuid,
             # the physical GPU PCI device
             "parent": cfgdev.parent,
             "type": cfgdev.mdev_information.type,
diff --git a/nova/virt/libvirt/host.py b/nova/virt/libvirt/host.py
index 92f58e6899..ebcc112534 100644
--- a/nova/virt/libvirt/host.py
+++ b/nova/virt/libvirt/host.py
@@ -1503,7 +1503,7 @@ class Host(object):
     def list_mediated_devices(self, flags=0):
         """Lookup mediated devices.
 
-        :returns: a list of virNodeDevice instance
+        :returns: a list of strings with the name of the instance
         """
         return self._list_devices("mdev", flags=flags)
 
diff --git a/nova/virt/libvirt/utils.py b/nova/virt/libvirt/utils.py
index 834f242c79..a1b9459b7e 100644
--- a/nova/virt/libvirt/utils.py
+++ b/nova/virt/libvirt/utils.py
@@ -581,17 +581,31 @@ def get_default_machine_type(arch: str) -> ty.Optional[str]:
 
 
 def mdev_name2uuid(mdev_name: str) -> str:
-    """Convert an mdev name (of the form mdev_<uuid_with_underscores>) to a
-    uuid (of the form 8-4-4-4-12).
+    """Convert an mdev name (of the form mdev_<uuid_with_underscores> or
+    mdev_<uuid_with_underscores>_<pciaddress>) to a uuid
+    (of the form 8-4-4-4-12).
+
+    :param mdev_name: the name of the mdev to parse the UUID from
+    :returns: string containing the uuid
     """
-    return str(uuid.UUID(mdev_name[5:].replace('_', '-')))
+    mdev_uuid = mdev_name[5:].replace('_', '-')
+    # Unconditionnally remove the PCI address from the name
+    mdev_uuid = mdev_uuid[:36]
+    return str(uuid.UUID(mdev_uuid))
+
 
+def mdev_uuid2name(mdev_uuid: str, parent: str = None) -> str:
+    """Convert an mdev uuid (of the form 8-4-4-4-12) and optionally its parent
+    device to a name (of the form mdev_<uuid_with_underscores>[_<pciid>]).
 
-def mdev_uuid2name(mdev_uuid: str) -> str:
-    """Convert an mdev uuid (of the form 8-4-4-4-12) to a name (of the form
-    mdev_<uuid_with_underscores>).
+    :param mdev_uuid: the uuid of the mediated device
+    :param parent: the parent device id for the mediated device
+    :returns: name of the mdev to reference in libvirt
     """
-    return "mdev_" + mdev_uuid.replace('-', '_')
+    name = "mdev_" + mdev_uuid.replace('-', '_')
+    if parent and parent.startswith('pci_'):
+        name = name + parent[4:]
+    return name
 
 
 def get_flags_by_flavor_specs(flavor: 'objects.Flavor') -> ty.Set[str]: