General Information
You might not have access to a GUI, always learn the CLI methods too.
From GUI Desktop on the system running KVM
On the Virtual Machine
vim /etc/default/grub
GRUB_CMDLINE_LINUX="rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet console=ttyS0"
On the KVM system
virsh console myserver1.example.com