BTW all of this is doable without libvirt via:
$ qemu-system-x86_64 -m 128 -M pc-i440fx-wily,accel=kvm --nodefaults --nographic --monitor stdio -device virtio-balloon-pci,id=balloon0
(qemu) info qtree
You can find the same "any_layout = false" at the device
dev: virtio-balloon-pci, id "balloon0" any_layout = false
BTW all of this is doable without libvirt via: wily,accel= kvm --nodefaults --nographic --monitor stdio -device virtio- balloon- pci,id= balloon0
$ qemu-system-x86_64 -m 128 -M pc-i440fx-
(qemu) info qtree
You can find the same "any_layout = false" at the device
any_ layout = false
dev: virtio-balloon-pci, id "balloon0"