Comment 12 for bug 1950406

Hey. So the error "No valid host was found." is caused when nova does not find an available host with the resources required in the flavor (like memory, isolated cores, required devices, etc). The message is generic to not expose the cloud data for the end-user. You can try to find more information in the logs, like the nova-compute.

I don't know if still missing anything else from the documentation, but you can take a look at the OpenStack documentation (https://docs.openstack.org/nova/xena/admin/pci-passthrough.html).