Fiddeling around with kvm again I wanted to use the monitor but on an instance that run with "-display non" cause I run it from the command line. Maybe one can access the monitor from VNC or SPICE I don't know but I found the option to redirect the monitor to a socket or any other network device. I went for a socket like this
-qmp unix:/var/run/kvm/qmp-default.sock,server,nowait --monitor stdio
Possible options for -qmp are the same as for -serial and can be found in the...