[DVR] Block ARP to dvr router's port instead of subnet's gateway

It may happen that subnet is connected to dvr router using IP address
different than subnet's gateway_ip.
So in br-tun arp to dvr router's port should be dropped instead of
dropping arp to subnet's gateway_ip (or mac in case of IPv6).

Change-Id: Ida6b7ae53f3fc76f54e389c5f7131b5a66f533ce
Closes-bug: #1831575

neutron/plugins/ml2/drivers/openvswitch/agent/ovs_dvr_neutron_agent.py

@@ -416,12 +416,11 @@ class OVSDVRNeutronAgent(object):
         # TODO(vivek) remove the IPv6 related flows once SNAT is not
         # used for IPv6 DVR.
         if ip_version == 4:
-            if subnet_info['gateway_ip']:
-                br.install_dvr_process_ipv4(
-                    vlan_tag=lvm.vlan, gateway_ip=subnet_info['gateway_ip'])
+            br.install_dvr_process_ipv4(
+                vlan_tag=lvm.vlan, gateway_ip=fixed_ip['ip_address'])
         else:
             br.install_dvr_process_ipv6(
-                vlan_tag=lvm.vlan, gateway_mac=subnet_info['gateway_mac'])
+                vlan_tag=lvm.vlan, gateway_mac=port.vif_mac)
         br.install_dvr_process(
             vlan_tag=lvm.vlan, vif_mac=port.vif_mac,
             dvr_mac_address=self.dvr_mac_address)

neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py

@@ -2856,7 +2856,7 @@ class TestOvsDvrNeutronAgent(object):
         return resp
 
     def _expected_install_dvr_process(self, lvid, port, ip_version,
-                                      gateway_ip, gateway_mac):
+                                      gateway_ip):
         if ip_version == n_const.IP_VERSION_4:
             ipvx_calls = [
                 mock.call.install_dvr_process_ipv4(
@@ -2867,7 +2867,7 @@ class TestOvsDvrNeutronAgent(object):
             ipvx_calls = [
                 mock.call.install_dvr_process_ipv6(
                     vlan_tag=lvid,
-                    gateway_mac=gateway_mac),
+                    gateway_mac=port.vif_mac),
             ]
         return ipvx_calls + [
             mock.call.install_dvr_process(
@@ -2881,12 +2881,13 @@ class TestOvsDvrNeutronAgent(object):
             self, device_owner, ip_version=n_const.IP_VERSION_4):
         self._setup_for_dvr_test()
         if ip_version == n_const.IP_VERSION_4:
-            gateway_ip = '1.1.1.1'
+            gateway_ip = '1.1.1.10'
             cidr = '1.1.1.0/24'
         else:
             gateway_ip = '2001:100::1'
             cidr = '2001:100::0/64'
-        self._port.vif_mac = gateway_mac = 'aa:bb:cc:11:22:33'
+        self._port.vif_mac = 'aa:bb:cc:11:22:33'
+        gateway_mac = 'aa:bb:cc:66:66:66'
         self._compute_port.vif_mac = '77:88:99:00:11:22'
         physical_network = self._physical_network
         segmentation_id = self._segmentation_id
@@ -2934,8 +2935,7 @@ class TestOvsDvrNeutronAgent(object):
                 port=self._port,
                 lvid=lvid,
                 ip_version=ip_version,
-                gateway_ip=gateway_ip,
-                gateway_mac=gateway_mac)
+                gateway_ip=self._fixed_ips[0]['ip_address'])
             expected_on_int_br = [
                 mock.call.provision_local_vlan(
                     port=int_ofp,
@@ -3023,8 +3023,7 @@ class TestOvsDvrNeutronAgent(object):
                 port=self._port,
                 lvid=lvid,
                 ip_version=ip_version,
-                gateway_ip=gateway_ip,
-                gateway_mac=gateway_mac)
+                gateway_ip=gateway_ip)
             self.assertEqual(expected_on_int_br, int_br.mock_calls)
             self.assertEqual(expected_on_tun_br, tun_br.mock_calls)
             self.assertEqual([], phys_br.mock_calls)
@@ -3285,8 +3284,7 @@ class TestOvsDvrNeutronAgent(object):
                     port=self._port,
                     lvid=lvid,
                     ip_version=ip_version,
-                    gateway_ip=gateway_ip,
-                    gateway_mac=gateway_mac)
+                    gateway_ip=gateway_ip)
                 self.assertEqual(expected_on_tun_br, tun_br.mock_calls)
 
         int_br.reset_mock()
@@ -3390,8 +3388,7 @@ class TestOvsDvrNeutronAgent(object):
                 port=self._port,
                 lvid=lvid,
                 ip_version=ip_version,
-                gateway_ip=gateway_ip,
-                gateway_mac=gateway_mac)
+                gateway_ip=gateway_ip)
             self.assertEqual(expected_on_tun_br, tun_br.mock_calls)
             int_br.reset_mock()
             tun_br.reset_mock()