Fix the vGPU dynamic options race

As we lookup the existing dynamic options *before* creating them as
_get_supported_vgpu_types() is called *before* compute init_host(),
we need to make sure we call again the dynamic options registration
within it.

Change-Id: Ib9387c381d39fac389374c731b210815c6d4af03
Closes-Bug: #1900006
(cherry picked from commit 2bd8900)

Author: sbauza

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

@@ -24988,6 +24988,20 @@ def test_get_supported_vgpu_types_with_invalid_pci_address(self):
                           libvirt_driver.LibvirtDriver,
                           fake.FakeVirtAPI(), False)
 
+    @mock.patch.object(nova.conf.devices, 'register_dynamic_opts')
+    def test_get_supported_vgpu_types_registering_dynamic_opts(self, rdo):
+        self.flags(enabled_vgpu_types=['nvidia-11', 'nvidia-12'],
+                   group='devices')
+
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        drvr._get_supported_vgpu_types()
+
+        # Okay below is confusing, but remember, ._get_supported_vgpu_types()
+        # is first called by the LibvirtDriver object creation, so when
+        # calling the above drvr._get_supported_vgpu_types() method, it will
+        # be the second time that register_dynamic_opts() will be called.
+        rdo.assert_has_calls([mock.call(CONF), mock.call(CONF)])
+
     def test_get_vgpu_type_per_pgpu(self):
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
         device = 'pci_0000_84_00_0'

nova/virt/libvirt/driver.py

@@ -6894,6 +6894,11 @@ def _get_supported_vgpu_types(self):
         if not CONF.devices.enabled_vgpu_types:
             return []
 
+        # Make sure we register all the types as the compute service could
+        # be calling this method before init_host()
+        if len(CONF.devices.enabled_vgpu_types) > 1:
+            nova.conf.devices.register_dynamic_opts(CONF)
+
         for vgpu_type in CONF.devices.enabled_vgpu_types:
             group = getattr(CONF, 'vgpu_%s' % vgpu_type, None)
             if group is None or not group.device_addresses: