Hello,
I know this is an old topic, but I also run into the same problem with my Micro server gen 8 with GPU passthrough.
Tried all steps but still the same message:
kvm: -device vfio-pci,host=07:00.0,id=hostpci0,bus=ich9-pcie-port-1,addr=0x0: vfio: failed to set iommu for container: Operation...