Specify path for vhost user sockets

This will be used for VIF plugging on chassis that have DPDK
enabled.

Change-Id: I3799b6ffea26423719827b3961ebf79c44c11b2c

src/reactive/neutron_api_plugin_ovn_handlers.py

@@ -99,6 +99,13 @@ def configure_neutron():
                 ('ovn_dhcp6_global_options',
                     ','.join(
                         _split_if_str(options.ovn_dhcp6_global_options))),
+                # NOTE(fnordahl): will be used on chassis with DPDK enabled
+                #
+                # Neutron will make per chassis decisions based on chassis
+                # configuration whether vif_type will be 'ovs' or 'vhostuser'.
+                # This allows having a mix of DPDK and non-DPDK nodes in the
+                # same deployment.
+                ('vhost_sock_dir', '/run/libvirt-vhost-user'),
             ],
             'ml2_type_geneve': [
                 ('vni_ranges', ','.join(

unit_tests/test_reactive_neutron_api_plugin_ovn_handlers.py

@@ -143,6 +143,7 @@ class TestOvnHandlers(test_utils.PatchHelper):
                                 ('dhcp_default_lease_time', 42),
                                 ('ovn_dhcp4_global_options', 'a:A4,b:B4'),
                                 ('ovn_dhcp6_global_options', 'a:A6,b:B6'),
+                                ('vhost_sock_dir', '/run/libvirt-vhost-user')
                             ],
                             'ml2_type_geneve': [
                                 ('vni_ranges', 'vnia:vniA,vnib:vniB'),