Fix traits to cpu flags mapping

Following keys like HW_CPU_X86_SVM and HW_CPU_X86_VMX are placed in TRAITS_CPU_MAPPING as part of a tuple instead of being direct keys.
This patch will flaten these tuples.
Closes-Bug: #2043030

Change-Id: Ia600ceb22c5939117095593b97ed94735c8f953c
(cherry picked from commit 99fe8c9)
(cherry picked from commit 55ed576)

Author: alisafari1998

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

@@ -710,6 +710,10 @@ def test_get_machine_type_from_image(self):
         os_mach_type = libvirt_utils.get_machine_type(image_meta)
         self.assertEqual('q35', os_mach_type)
 
+    def test_make_reverse_cpu_traits_mapping(self):
+        for k in libvirt_utils.make_reverse_cpu_traits_mapping():
+            self.assertIsInstance(k, str)
+
     def test_get_flags_by_flavor_specs(self):
         flavor = objects.Flavor(
             id=1, flavorid='fakeid-1', name='fake1.small', memory_mb=128,
@@ -718,11 +722,15 @@ def test_get_flags_by_flavor_specs(self):
                 'trait:%s' % os_traits.HW_CPU_X86_3DNOW: 'required',
                 'trait:%s' % os_traits.HW_CPU_X86_SSE2: 'required',
                 'trait:%s' % os_traits.HW_CPU_HYPERTHREADING: 'required',
+                'trait:%s' % os_traits.HW_CPU_X86_INTEL_VMX: 'required',
+                'trait:%s' % os_traits.HW_CPU_X86_VMX: 'required',
+                'trait:%s' % os_traits.HW_CPU_X86_SVM: 'required',
+                'trait:%s' % os_traits.HW_CPU_X86_AMD_SVM: 'required',
             })
         traits = libvirt_utils.get_flags_by_flavor_specs(flavor)
         # we shouldn't see the hyperthreading trait since that's a valid trait
         # but not a CPU flag
-        self.assertEqual(set(['3dnow', 'sse2']), traits)
+        self.assertEqual(set(['3dnow', 'sse2', 'vmx', 'svm']), traits)
 
     @mock.patch('nova.virt.libvirt.utils.copy_image')
     @mock.patch('nova.privsep.path.chown')

nova/virt/libvirt/utils.py

@@ -103,8 +103,20 @@
     'xop': os_traits.HW_CPU_X86_XOP
 }
 
+
+def make_reverse_cpu_traits_mapping() -> ty.Dict[str, str]:
+    traits_cpu_mapping = dict()
+    for k, v in CPU_TRAITS_MAPPING.items():
+        if isinstance(v, tuple):
+            for trait in v:
+                traits_cpu_mapping[trait] = k
+        else:
+            traits_cpu_mapping[v] = k
+    return traits_cpu_mapping
+
+
 # Reverse CPU_TRAITS_MAPPING
-TRAITS_CPU_MAPPING = {v: k for k, v in CPU_TRAITS_MAPPING.items()}
+TRAITS_CPU_MAPPING = make_reverse_cpu_traits_mapping()
 
 # global directory for emulated TPM
 VTPM_DIR = '/var/lib/libvirt/swtpm/'