The pgsize bitmap is used to advertise the page sizes our hardware supports
to the IOMMU core, which will then use this information to split physically
contiguous memory regions it is mapping into page sizes that we support.

Traditionally the IOMMU core just handed us the mappings directly, after
making sure the size is an order of a 4KiB page and that the mapping has
natural alignment. To retain this behavior, we currently advertise that we
support all page sizes that are an order of 4KiB.

We are about to utilize the new IOMMU map/unmap_pages APIs. We could change
this to advertise the real page sizes we support.
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20210720020615.4144323-2-baolu.lu@linux.intel.comSigned-off-by: Joerg Roedel <jroedel@suse.de>