Fix receiving multicast traffic

By default libvirt does not allow traffic destined for other MAC
addresses to reach VMs when using a macvtap interface. This prevents
multicast from working.

This change fixes the issue by setting trustGuestRxFilters to yes for
macvtap interfaces.

Author: markgoddard

templates/vm.xml.j2

@@ -47,7 +47,7 @@
 {% endfor %}
 {% for interface in interfaces %}
 {% if interface.type is defined and interface.type == 'direct' %}
-    <interface type='direct'>
+    <interface type='direct' trustGuestRxFilters='yes'>
       <source dev='{{ interface.source.dev }}' mode='{{ interface.source.mode | default('vepa') }}'/>
 {% elif interface.type is defined and interface.type == 'bridge' %}
     <interface type='bridge'>