@MJGZ51 Hi!
Since 8.3 PCI passthrough is part of the XAPI and come with dedicated xe commands:
xe pci-list to have the list of PCI devices and then:
xe pci-disable-dom0-access uuid=<pci uuid> to hide th device from dom0
xe pci-enable-dom0-access uuid=<pci uuid> to unhide the from dom0
These are the same API calls made by XO or any XAPI clients
No need to edit manually the cmdline anymore!
Regards