From 63d6ecd99b7dec06cf0cf8358b43b0d8fa607504 Mon Sep 17 00:00:00 2001
From: Artom Lifshitz <alifshit@redhat.com>
Date: Fri, 28 Oct 2022 19:42:21 -0400
Subject: Reproduce bug 1995153

If we first boot an instance with NUMA topology on a host, any
subsequent attempts to boot instances with the `socket` PCI NUMA
policy will fail with `Cannot load 'socket' in the base class`.
Demonstrate this in a functional test.

Change-Id: I63f4e3dfa38f65b73d0051b8e52b1abd0f027e9b
Related-bug: 1995153
---
 .../functional/regressions/test_bug_1995153.py     | 109 +++++++++++++++++++++
 1 file changed, 109 insertions(+)
 create mode 100644 nova/tests/functional/regressions/test_bug_1995153.py

diff --git a/nova/tests/functional/regressions/test_bug_1995153.py b/nova/tests/functional/regressions/test_bug_1995153.py
new file mode 100644
index 0000000000..c897156d99
--- /dev/null
+++ b/nova/tests/functional/regressions/test_bug_1995153.py
@@ -0,0 +1,109 @@
+# Copyright (C) 2023 Red Hat, Inc
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+
+import fixtures
+from unittest import mock
+
+from oslo_serialization import jsonutils
+from oslo_utils import units
+
+from nova.objects import fields
+from nova.tests.fixtures import libvirt as fakelibvirt
+from nova.tests.functional import integrated_helpers
+from nova.tests.functional.libvirt import base
+
+
+class Bug1995153RegressionTest(
+    base.ServersTestBase,
+    integrated_helpers.InstanceHelperMixin
+):
+
+    ADDITIONAL_FILTERS = ['NUMATopologyFilter', 'PciPassthroughFilter']
+
+    ALIAS_NAME = 'a1'
+    PCI_DEVICE_SPEC = [jsonutils.dumps(
+        {
+            'vendor_id': fakelibvirt.PCI_VEND_ID,
+            'product_id': fakelibvirt.PCI_PROD_ID,
+        }
+    )]
+    # we set the numa_affinity policy to required to ensure strict affinity
+    # between pci devices and the guest cpu and memory will be enforced.
+    PCI_ALIAS = [jsonutils.dumps(
+        {
+            'vendor_id': fakelibvirt.PCI_VEND_ID,
+            'product_id': fakelibvirt.PCI_PROD_ID,
+            'name': ALIAS_NAME,
+            'device_type': fields.PciDeviceType.STANDARD,
+            'numa_policy': fields.PCINUMAAffinityPolicy.REQUIRED,
+        }
+    )]
+
+    def setUp(self):
+        super(Bug1995153RegressionTest, self).setUp()
+        self.flags(
+            device_spec=self.PCI_DEVICE_SPEC,
+            alias=self.PCI_ALIAS,
+            group='pci'
+        )
+        host_manager = self.scheduler.manager.host_manager
+        pci_filter_class = host_manager.filter_cls_map['PciPassthroughFilter']
+        host_pass_mock = mock.Mock(wraps=pci_filter_class().host_passes)
+        self.mock_filter = self.useFixture(fixtures.MockPatch(
+            'nova.scheduler.filters.pci_passthrough_filter'
+            '.PciPassthroughFilter.host_passes',
+            side_effect=host_pass_mock)).mock
+
+    def test_socket_policy_bug_1995153(self):
+        """The numa_usage_from_instance_numa() method in hardware.py saves the
+        host NUMAToplogy object with NUMACells that have no `socket` set. This
+        was an omission in the original implementation of the `socket` PCI NUMA
+        affinity policy. The consequence is that any code path that calls into
+        numa_usage_from_instance_numa() will clobber the host NUMA topology in
+        the database with a socket-less version. Booting an instance with NUMA
+        toplogy will do that, for example. If then a second instance is booted
+        with the `socket` PCI NUMA affinity policy, it will read the
+        socket-less host NUMATopology from the database, and error out with a
+        NotImplementedError. This is bug 1995153.
+        """
+        host_info = fakelibvirt.HostInfo(
+            cpu_nodes=2, cpu_sockets=1, cpu_cores=2, cpu_threads=2,
+            kB_mem=(16 * units.Gi) // units.Ki)
+        self.flags(cpu_dedicated_set='0-3', group='compute')
+        pci_info = fakelibvirt.HostPCIDevicesInfo(num_pci=1, numa_node=1)
+
+        self.start_compute(host_info=host_info, pci_info=pci_info)
+
+        extra_spec = {
+            'hw:cpu_policy': 'dedicated',
+            'pci_passthrough:alias': '%s:1' % self.ALIAS_NAME,
+            'hw:pci_numa_affinity_policy': 'socket'
+        }
+        # Boot a first instance with a guest NUMA topology to run the buggy
+        # code in numa_usage_from_instance_numa() and save the socket-less host
+        # NUMATopology to the database.
+        self._create_server(
+            flavor_id=self._create_flavor(
+                extra_spec={'hw:cpu_policy': 'dedicated'}))
+
+        # FIXME(artom) Attempt to boot an instance with the `socket` PCI NUMA
+        # affinity policy and observe the fireworks.
+        flavor_id = self._create_flavor(extra_spec=extra_spec)
+        server = self._create_server(flavor_id=flavor_id,
+                                     expected_state='ERROR')
+        self.assertIn('fault', server)
+        self.assertIn('NotImplementedError', server['fault']['message'])
+        self.assertTrue(self.mock_filter.called)
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