Guest and host cannot see each other using linux-kvm and macvtap

I asked this question on IRC and it appears that macvtap

injects guest traffic into the network stack too low for that

The solution is then to add a network interface for the guest and the host to communicate, or stay with the old bridged solution...

virt-manager says explictly that macvtap does not work for host to guest network communications when you set it up. I simply added a second nat based interface, set it up in the guest, and use that to communicate with my host.