- name: Fetch list of all VMs
  community.libvirt.virt:
    command: list_vms
  register: vms_list

- name: Fail if VM does not exist
  ansible.builtin.fail:
    msg: "VM {{ libvirt_vm_name }} does not exist."
  when: libvirt_vm_name | string not in vms_list.list_vms