Ensure MAC addresses characters are in the same case

Currently neutron can report ports to have MAC addresses
in upper case when they're created like that. In the meanwhile
libvirt configuration file always stores MAC in lower case
which leads to KeyError while trying to retrieve migrate_vif.

Closes-Bug: #1945646
Change-Id: Ie3129ee395427337e9abcef2f938012608f643e1
(cherry picked from commit 6a15169)

Author: Dmitriy Rabotyagov

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

@@ -949,7 +949,48 @@ def test_update_vif_xml_no_matching_vif(self):
         doc = etree.fromstring(original_xml)
         ex = self.assertRaises(KeyError, migration._update_vif_xml,
                                doc, data, get_vif_config)
-        self.assertIn("CA:FE:DE:AD:BE:EF", str(ex))
+        self.assertIn("ca:fe:de:ad:be:ef", str(ex))
+
+    def test_update_vif_xml_lower_case_mac(self):
+        """Tests that the vif in the migrate data is not found in the existing
+        guest interfaces.
+        """
+        conf = vconfig.LibvirtConfigGuestInterface()
+        conf.net_type = "bridge"
+        conf.source_dev = "qbra188171c-ea"
+        conf.target_dev = "tapa188171c-ea"
+        conf.mac_addr = "DE:AD:BE:EF:CA:FE"
+        conf.model = "virtio"
+        original_xml = """<domain>
+        <uuid>3de6550a-8596-4937-8046-9d862036bca5</uuid>
+        <devices>
+            <interface type="bridge">
+                <mac address="de:ad:be:ef:ca:fe"/>
+                <model type="virtio"/>
+                <source bridge="qbra188171c-ea"/>
+                <target dev="tapa188171c-ea"/>
+                <virtualport type="openvswitch">
+                    <parameters interfaceid="%s"/>
+                </virtualport>
+                <address type='pci' domain='0x0000' bus='0x00' slot='0x04'
+                        function='0x0'/>
+            </interface>
+        </devices>
+        </domain>""" % uuids.ovs
+        expected_xml = """<domain>
+         <uuid>3de6550a-8596-4937-8046-9d862036bca5</uuid>
+         <devices>
+            <interface type="bridge">
+                <mac address="DE:AD:BE:EF:CA:FE"/>
+                <model type="virtio"/>
+                <source bridge="qbra188171c-ea"/>
+                <target dev="tapa188171c-ea"/>
+                <address type='pci' domain='0x0000' bus='0x00' slot='0x04'
+                 function='0x0'/>
+            </interface>
+         </devices>
+        </domain>"""
+        self._test_update_vif_xml(conf, original_xml, expected_xml)
 
 
 class MigrationMonitorTestCase(test.NoDBTestCase):

nova/virt/libvirt/migration.py

@@ -339,14 +339,21 @@ def _update_vif_xml(xml_doc, migrate_data, get_vif_config):
     instance_uuid = xml_doc.findtext('uuid')
     parser = etree.XMLParser(remove_blank_text=True)
     interface_nodes = xml_doc.findall('./devices/interface')
-    migrate_vif_by_mac = {vif.source_vif['address']: vif
+    # MAC address stored for port in neutron DB and in domain XML
+    # might be in different cases, so to harmonize that
+    # we convert MAC to lower case for dict key.
+    migrate_vif_by_mac = {vif.source_vif['address'].lower(): vif
                           for vif in migrate_data.vifs}
     for interface_dev in interface_nodes:
         mac = interface_dev.find('mac')
         mac = mac if mac is not None else {}
         mac_addr = mac.get('address')
         if mac_addr:
-            migrate_vif = migrate_vif_by_mac[mac_addr]
+            # MAC address stored in libvirt should always be normalized
+            # and stored in lower case. But just to be extra safe here
+            # we still normalize MAC retrieved from XML to be absolutely
+            # sure it will be the same with the Neutron provided one.
+            migrate_vif = migrate_vif_by_mac[mac_addr.lower()]
             vif = migrate_vif.get_dest_vif()
             # get_vif_config is a partial function of
             # nova.virt.libvirt.vif.LibvirtGenericVIFDriver.get_config