If you're trying to start a cloud-init based Ubuntu VM with KVM you will suffer long boot times and confusing output on the terminal. If you want to get rid of it you need to remove cloud-init.

1. wait until the VM boots
2. login
3. echo 'datasource_list: [ None ]' | sudo -s tee /etc/cloud/cloud.cfg.d/90_dpkg.cfg
4. sudo apt-get purge cloud-init
5. sudo rm -rf /etc/cloud/; sudo rm -rf /var/lib/cloud/
6. reboot