Merge "Support multiple allocations for vGPUs"

doc/source/admin/virtual-gpu.rst

@@ -172,6 +172,39 @@ provided by compute nodes.
    $ openstack server create --flavor vgpu_1 --image cirros-0.3.5-x86_64-uec --wait test-vgpu
 
 
+Ask for more than one vGPU per instance by the flavor
+-----------------------------------------------------
+
+.. versionchanged:: 33.0.0
+
+We have an open bug report `bug 1758086`_ explaining that the nvidia driver
+doesn't support more than one vGPU per instance (and per GPU resource - which
+can be a physical GPU or a virtual function, see nvidia docs for more details).
+In order to alleviate this problem, this is mandatory to require in the flavor
+to have all the vGPUs to be spread between multiple GPU resource providers.
+
+For example, you can request two groups of vGPUs this way :
+
+.. code-block:: console
+
+   $ openstack flavor set vgpu_2 --property "resources1:VGPU=1" \
+                                 --property "resources2:VGPU=1" \
+
+
+With SR-IOV GPUs (you may need to refer to nvidia documentation to know the
+distinction), this will work without requiring further attributes as every
+single VGPU Resource Provider only provides a single VGPU resource.
+
+For non-SRIOV GPUs, you may require other properties in order to request
+Placement to allocate you some host with two distinct GPUs.
+You may need to create distinct custom traits per GPU or custom resource
+classes for explicitly telling in your flavor that you would want resources
+from distinct entities, or you could use ``group_policy=isolate`` as a property
+but you would need to make sure that you don't ask for other resources but
+virtual GPUs in your flavor or Placement would shard all the allocations for
+*all* resource groups.
+
+
 How to discover a GPU type
 --------------------------
 
@@ -490,6 +523,7 @@ For nested vGPUs:
 .. _bug 1762688: https://bugs.launchpad.net/nova/+bug/1762688
 .. _bug 1948705: https://bugs.launchpad.net/nova/+bug/1948705
 .. _supports vGPU live-migrations: https://specs.openstack.org/openstack/nova-specs/specs/2024.1/approved/libvirt-mdev-live-migrate.html
+.. _bug 1758086: https://bugs.launchpad.net/nova/+bug/1758086
 
 .. Links
 .. _Intel GVT-g: https://01.org/igvt-g

nova/tests/functional/libvirt/test_vgpu.py

@@ -321,10 +321,16 @@ class VGPUTests(VGPUTestBase):
             image_uuid='155d900f-4e14-4e4c-a73d-069cbf4541e6',
             flavor_id=flavor, networks='auto', host=self.compute1.host)
 
-        # FIXME(sbauza): Unfortunately, we only accept one allocation per
+        # Eventually, we have two allocations and two mdevs
-        # instance by the libvirt driver as you can see in _allocate_mdevs().
+        self.assert_mdev_usage(self.compute1, expected_amount=2)
-        # So, eventually, we only have one vGPU for this instance.
+        # Let's verify those are spread between both GPU RPs
-        self.assert_mdev_usage(self.compute1, expected_amount=1)
+        rp_uuid = self.compute_rp_uuids['host1']
+        rp_uuids = self._get_all_rp_uuids_in_a_tree(rp_uuid)
+        for rp in rp_uuids:
+            inventory = self._get_provider_inventory(rp)
+            if orc.VGPU in inventory:
+                usage = self._get_provider_usages(rp)
+                self.assertEqual(1, usage[orc.VGPU])
 
 
 class VGPUMultipleTypesTests(VGPUTestBase):

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

@@ -29397,13 +29397,14 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
             }
         }
         drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
-        self.assertIsNone(drvr._allocate_mdevs(allocations=allocations))
+        self.assertEqual([], drvr._allocate_mdevs(allocations=allocations))
 
     def _get_fake_provider_tree_with_vgpu(self):
-        """Returns a fake ProviderTree with VGPU inventory on two children RPs
+        """Returns a fake ProviderTree with VGPU inventory on 3 children RPs
-        with one with a correct name and the other one wrong.
+        with the first two with a correct name and the third wrong.
 
-        The child provider is named rp1 and its UUID is uuids.rp1.
+        The child providers are named rp[1-3] and their UUIDs are uuids.rp1,
+        uuids.rp2 and uuids.rp3
         """
         cn_rp = dict(
             uuid=uuids.cn,
@@ -29423,10 +29424,14 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
         pt.new_child(cn_rp['name'] + '_' + 'pci_0000_06_00_0', cn_rp['uuid'],
                      uuid=uuids.rp1, generation=0)
         pt.update_inventory(uuids.rp1, vgpu_rp_inv)
-        # Create a second child with a bad naming convention
+        # Create a second child also with a correct naming attribute
-        pt.new_child('oops_I_did_it_again', cn_rp['uuid'],
+        pt.new_child(cn_rp['name'] + '_' + 'pci_0000_07_00_0', cn_rp['uuid'],
                      uuid=uuids.rp2, generation=0)
         pt.update_inventory(uuids.rp2, vgpu_rp_inv)
+        # Create a third child with a bad naming convention
+        pt.new_child('oops_I_did_it_again', cn_rp['uuid'],
+                     uuid=uuids.rp3, generation=0)
+        pt.update_inventory(uuids.rp3, vgpu_rp_inv)
         return pt
 
     @mock.patch.object(libvirt_driver.LibvirtDriver,
@@ -29453,6 +29458,37 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
         get_unassigned_mdevs.assert_called_once_with('pci_0000_06_00_0',
                                                      ['nvidia-11'])
 
+    @mock.patch.object(libvirt_driver.LibvirtDriver,
+                       '_get_existing_mdevs_not_assigned')
+    @mock.patch.object(libvirt_driver.LibvirtDriver,
+                       '_get_supported_mdev_resource_classes')
+    def test_allocate_mdevs_with_multiple_allocs(self, get_supported_mdev_rcs,
+                                                 get_unassigned_mdevs):
+        self.flags(enabled_mdev_types=['nvidia-11'], group='devices')
+        allocations = {
+            uuids.rp1: {
+                'resources': {
+                    orc.VGPU: 1,
+                }
+            },
+            uuids.rp2: {
+                'resources': {
+                    orc.VGPU: 1,
+                }
+            }
+        }
+        get_supported_mdev_rcs.return_value = set([orc.VGPU])
+        get_unassigned_mdevs.side_effect = (set([uuids.mdev1]),
+                                            set([uuids.mdev2]))
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), False)
+        # Mock the fact update_provider_tree() should have run
+        drvr.provider_tree = self._get_fake_provider_tree_with_vgpu()
+        self.assertEqual([uuids.mdev1, uuids.mdev2],
+                         drvr._allocate_mdevs(allocations=allocations))
+        get_unassigned_mdevs.assert_has_calls(
+            [mock.call('pci_0000_06_00_0', ['nvidia-11']),
+             mock.call('pci_0000_07_00_0', ['nvidia-11'])])
+
     @mock.patch.object(libvirt_driver.LibvirtDriver,
                        '_get_mdev_capable_devices')
     @mock.patch.object(libvirt_driver.LibvirtDriver,
@@ -29513,7 +29549,7 @@ class LibvirtDriverTestCase(test.NoDBTestCase, TraitsComparisonMixin):
 
         # Test that we were unable to guess the RP name
         allocations = {
-            uuids.rp2: {
+            uuids.rp3: {
                 'resources': {
                     orc.VGPU: 1,
                 }

nova/virt/libvirt/driver.py

@@ -9237,43 +9237,39 @@ class LibvirtDriver(driver.ComputeDriver):
                             That code is supporting Placement API version 1.12
         """
         vgpu_allocations = self._vgpu_allocations(allocations)
-        if not vgpu_allocations:
+
-            return
+        chosen_mdevs = []
-        # TODO(sbauza): For the moment, we only support allocations for only
+        for rp_uuid, alloc in vgpu_allocations.items():
-        # one pGPU.
-        if len(vgpu_allocations) > 1:
-            LOG.warning('More than one allocation was passed over to libvirt '
-                        'while at the moment libvirt only supports one. Only '
-                        'the first allocation will be looked up.')
-        rp_uuid, alloc = next(iter(vgpu_allocations.items()))
             # We only have one allocation with a supported resource class
+            # FIXME(sbauza): If a new vfio-mdev usage supports more than one
+            # type per PCI device, we would need to modify this. For the
+            # moment, all of the vfio-mdev drivers that we know only support
+            # one type per mdev-supported device.
             vgpus_asked = list(alloc['resources'].values())[0]
 
-        # Find if we allocated against a specific pGPU (and then the allocation
-        # is made against a child RP) or any pGPU (in case the VGPU inventory
-        # is still on the root RP)
             try:
                 allocated_rp = self.provider_tree.data(rp_uuid)
             except ValueError:
                 # The provider doesn't exist, return a better understandable
                 # exception
                 raise exception.ComputeResourcesUnavailable(
-                reason='mdev-capable resource is not available')
+                    reason='Resource Provider %s is missing' % rp_uuid)
-        # FIXME(sbauza): The functional reshape test assumes that we could
-        # run _allocate_mdevs() against non-nested RPs but this is impossible
-        # as all inventories have been reshaped *before now* since it's done
-        # on init_host() (when the compute restarts or whatever else calls it).
-        # That said, since fixing the functional test isn't easy yet, let's
-        # assume we still support a non-nested RP for now.
-        if allocated_rp.parent_uuid is None:
-            # We are on a root RP
-            parent_device = None
-        else:
             rp_name = allocated_rp.name
             # There can be multiple roots, we need to find the root name
             # to guess the physical device name
             roots = list(self.provider_tree.roots)
             for root in roots:
+                # FIXME(sbauza): The functional reshape test assumes that we
+                # could run _allocate_mdevs() against non-nested RPs but this
+                # is impossible as all inventories have been reshaped *before
+                # now* since it's done on init_host() (when the compute
+                # restarts or whatever else calls it). That said, since fixing
+                # the functional test isn't easy yet, let's assume we still
+                # support a non-nested RP for now.
+                if allocated_rp.parent_uuid is None:
+                    # We are on a root RP
+                    parent_device = None
+                    break
                 if rp_name.startswith(root.name + '_'):
                     # The RP name convention is :
                     #    root_name + '_' + parent_device
@@ -9295,7 +9291,6 @@ class LibvirtDriver(driver.ComputeDriver):
             mdevs_available = self._get_existing_mdevs_not_assigned(
                 parent_device, supported_types)
 
-        chosen_mdevs = []
             for c in range(vgpus_asked):
                 chosen_mdev = None
                 if mdevs_available:
@@ -9303,10 +9298,12 @@ class LibvirtDriver(driver.ComputeDriver):
                     chosen_mdev = mdevs_available.pop()
                 else:
                     LOG.debug('No available mdevs where found. '
-                          'Creating an new one...')
+                              'Creating a new one...')
-                chosen_mdev = self._create_new_mediated_device(parent_device)
+                    chosen_mdev = self._create_new_mediated_device(
+                        parent_device)
                 if not chosen_mdev:
-                # If we can't find devices having available VGPUs, just raise
+                    # If we can't find devices having available VGPUs, just
+                    # raise
                     raise exception.ComputeResourcesUnavailable(
                         reason='mdev-capable resource is not available')
                 else:

releasenotes/notes/bug-1758086-e9d147380d149789.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    You can now request different resource groups in your flavor for VGPU or
+    generic mediated device custom resource classes. Previously, only the
+    first resource request group was honored. See `bug #1758086`_ for more
+    details.
+
+    .. _bug #1758086: https://bugs.launchpad.net/nova/+bug/1758086