On Mon, Jun 20, 2022 at 12:00:46AM -0300, Jason Gunthorpe wrote: > On Fri, Jun 17, 2022 at 01:54:05AM -0700, Christoph Hellwig wrote: > > There is a bunch of code an comments in the iommu type1 code that > > suggest we can pin memory that is not page backed. > > AFAIK you can.. The whole follow_pte() mechanism allows raw PFNs to be > loaded into the type1 maps and the pin API will happily return > them. This happens in almost every qemu scenario because PCI MMIO BAR > memory ends up routed down this path. Indeed, my read wasn't deep enough. Which means that we can't change the ->pin_pages interface to return a struct pages array, as we don't have one for those.
