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.

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

Note: conflict is caused by not having six.text_type removal patch
I779bd1446dc1f070fa5100ccccda7881fa508d79 in stable/victoria.
Original assertion method was preserved to resolve this conflict.

Closes-Bug: #1945646
Change-Id: Ie3129ee395427337e9abcef2f938012608f643e1
(cherry picked from commit 6a15169)
(cherry picked from commit 63a6388)
(cherry picked from commit 6c3d5de)

Author: Dmitriy Rabotyagov

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

@@ -991,7 +991,48 @@ 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", six.text_type(ex))
+        self.assertIn("ca:fe:de:ad:be:ef", six.text_type(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

@@ -344,14 +344,21 @@ 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