Store correct VirtCPUTopology

When booting a NUMA-enabled instance, the scheduler generates and
stores a meaningless VirtCPUTopology as part of the InstanceNumaCell
objects. A correct value is later generated and used in libvirt XML
generation but this is not stored. Fix this by skipping the initial
generation and storing of the VirtCPUTopology in favour of storing
the correctly generated version.

Change-Id: Ief4fcdec0e107a233225ebd68207ac6172b3751e
Closes-bug: #1466780

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

@@ -4050,6 +4050,32 @@ class LibvirtConnTestCase(test.NoDBTestCase):
         self.assertEqual(conf.cpu.cores, 1)
         self.assertEqual(conf.cpu.threads, 1)
 
+    @mock.patch.object(host.Host, "has_min_version", return_value=True)
+    def test_get_guest_cpu_config_numa_topology(self, mock_has_min_version):
+        drvr = libvirt_driver.LibvirtDriver(fake.FakeVirtAPI(), True)
+        instance_ref = objects.Instance(**self.test_instance)
+        instance_ref.flavor.vcpus = 2
+        instance_ref.numa_topology = objects.InstanceNUMATopology(cells=[
+            objects.InstanceNUMACell(
+                id=0,
+                cpuset=set([0, 1]),
+                memory=1024,
+                cpu_pinning={})])
+        image_meta = {}
+        disk_info = blockinfo.get_disk_info(CONF.libvirt.virt_type,
+                                            instance_ref,
+                                            image_meta)
+
+        self.assertIsNone(instance_ref.numa_topology.cells[0].cpu_topology)
+
+        drvr._get_guest_config(
+            instance_ref, _fake_network_info(self.stubs, 1), {}, disk_info)
+
+        topo = instance_ref.numa_topology.cells[0].cpu_topology
+        self.assertIsNotNone(topo)
+        self.assertEqual(topo.cores * topo.sockets * topo.threads,
+                         instance_ref.flavor.vcpus)
+
     def test_get_guest_cpu_topology(self):
         instance_ref = objects.Instance(**self.test_instance)
         instance_ref.flavor.vcpus = 8

nova/virt/hardware.py

@@ -698,6 +698,7 @@ def _pack_instance_onto_cores(available_siblings, instance_cell, host_cell_id):
                 pinning = zip(sorted(instance_cell.cpuset),
                               itertools.chain(*sliced_sibs))
 
+            # NOTE(sfinucan) - this may be overriden later on by the drivers
             topology = (instance_cell.cpu_topology or
                         objects.VirtCPUTopology(sockets=1,
                                                 cores=len(sliced_sibs),

nova/virt/libvirt/driver.py

@@ -3083,6 +3083,10 @@ class LibvirtDriver(driver.ComputeDriver):
         topology = hardware.get_best_cpu_topology(
                 flavor, image_meta, numa_topology=instance_numa_topology)
 
+        if instance_numa_topology:
+            for cell in instance_numa_topology.cells:
+                cell.cpu_topology = topology
+
         cpu.sockets = topology.sockets
         cpu.cores = topology.cores
         cpu.threads = topology.threads