Hi, I was testing devices assignment behind a non-ACS switch and to my surprise, Devices connected to different ports were assigned different iommu-groups. The reason for this behavior is that pci_acs_enabled(...) considers the switch Upstream port to have ACS enabled. http://elixir.free-electrons.com/linux/v4.13.1/source/drivers/pci/pci.c#L2914 (the upstream port is not a multifunction device). I'm not sure what the correct solution is but I believe, the upstream port Shouldn't be considered in pci_acs_path_enable(...). Thanks, Ilya
