One opportunity to create a vhost on a KVM host is to use vmbuilder like e.g. so:
vmbuilder kvm ubuntu --suite trusty --flavour virtual --arch i386 \ -o --libvirt qemu:///system
In order to use vmbuilder the package python-vm-builder has to be installed. For more options see the man page of vmbuilder.
When creating a vhost with vmbuilder the process can terminate with a PCI device error.
The error is caused by an Ubuntu specific change to kvm: Ubuntu sets a specific vhost type which is not properly checked by vmbuilder.
The error is fixed by a patch for libvirt-bin version 1.2.8. Thus updating libvirt-bin to at least version v1.2.8 solves the problem.