[libvirt] How to config my VM to use KVM with libvirt?

Hi, I have a VM running under libvirt, and it is currently run with -no-kvm option (I saw that in "ps" output). Now I want to run this VM with KVM. How can I reconfigure it for that? I looked into its configuration file under /etc/libvirt/qemu, but didnt see any option to turn KVM on. Thanks, J