brctl delif br0 tap0 brctl delif br0 tap1 kvm -no-reboot -m 1300 -hda /dev/mapper/loop0p1 -boot order=c -net nic,macaddr="DE:AD:BE:EF:EC:B6" -net bridge,br=br0 kvm -no-reboot -m 1300 -hda /dev/mapper/loop1p1 -boot order=c -net nic,macaddr="DE:AD:BE:EF:EC:B7" -net bridge,br=br0 

In the scenario you used macvtap is being used.
If all VM's should be able to reach other VM's as well as host letting br0 act as a switch is best option.

brctl delif br0 tap0 brctl delif br0 tap1 kvm -no-reboot -m 1300 -hda /dev/mapper/loop0p1 -boot order=c -net nic,macaddr="DE:AD:BE:EF:EC:B6" -net bridge,br=br0 kvm -no-reboot -m 1300 -hda /dev/mapper/loop1p1 -boot order=c -net nic,macaddr="DE:AD:BE:EF:EC:B7" -net bridge,br=br0 

In your current scenario tap is being used.
If all VM's should be able to reach other VM's as well as virtualisation host letting br0 act as a switch is a option.

Another way would be to use macvtap in bridge mode or even using openvswitch.