shutdown kvm-guests without libvirt/virsh
Solution 1:
If you have started your VM with the monitor option (-monitor unix:/tmp/file.mon,server,nowait ), you can stop it by using echo 'system_powerdown' | socat - UNIX-CONNECT:/tmp/file.mon.
It send a ACPI signal to the VM, which can use it as you push your power button, and then do a shutdown.