If you'd like to be able to easily see which one of your kvm guests is the cpu hog, make links from to qemu-kvm
cd /usr/local/bin
ln -s /usr/bin/qemu-kvm vm_magneto
virsh edit magneto
# change emulator to
<emulator>/usr/local/bin/vm_magneto</emulator>
virsh reload
virsh shutdown magneto
virsh start magneto