Setting up bridged networking with KVM

You should not need to use static settings instead.
Also, I see that you have already found this answer

For a dynamic IP address solution, you should set up a real bridge and use it. Your interfaces file should become:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

auto br0
iface br0 inet dhcp
   bridge_ports p17p1
   bridge_fd 9
   bridge_hello 2
   bridge_maxage 12
   bridge_stp off

Note: I got some of the settings from the Ubuntu server guide