If you have a fancy "USB" port which allows connexion of graphics cards (so basically a PCIe port, although it also accepts USB), chances are that you can do whatever you want with unrestricted DMA through this port. It seems that letting Windows use the IOMMU is only allowed on the Enterprise edition, which is basically unavailable for the general public. So facing determined and/or well financed actors, it is as if the Windows login do not exist anymore for tons of Windows users.