Pcie Device Remapping -

PCIe switches often allow peer-to-peer traffic between downstream ports without going through the IOMMU. This breaks isolation. For true remapping and passthrough, the PCIe topology must support to force all traffic up to the root complex where the IOMMU resides. Without ACS, devices behind a switch can see each other’s memory—a major security flaw.

If a device doesn't work after remapping, look for these common errors.

dmesg | grep -e DMAR -e IOMMU

ls -l /sys/bus/pci/devices/0000:02:00.0/iommu_group/devices/