Patches 1 and 2 clearly are intended for 4.15; patch 3 is possibly
controversial (along the lines of similar relaxation proposed for
other (sub-)hypercalls), and hence unlikely to be a candidate as
well.

1: never permit mapping transitive grants
2: bypass IOMMU (un)mapping when a domain is (un)mapping its own grant
3: GTF_sub_page is a v2-only flag

Jan