Marc-André and I just got different thoughts about a design direction. I prefer to have all the frontend virtio devices (net, scsi, console etc.) from the same VM to be supported by one backend vhost-pci device (N-1), while Marc-André prefers to have each frontend virtio device be supported by a backend vhost-pci device (N-N).
I suggested 1-1 (not n-n, but you can have several 1-1 pairs), unless you have a good reason to do differently, starting from the use case (is there a case that requires several backends/consumers in the same VM? if yes, 1-1 design could still fit). If it's to save guest memory space, it may not be a good enough reason, but I don't see clearly the implications.