The umem DMA list calculation was locked at 4k pages due to confusion
around how this API works and is used when larger pages are present.
The conclusion is:
- umem's cannot extend past what is mapped into the process, so creating
a lage page size and referring to a sub-range is not allowed
- umem's must always have a page offset of zero, except for sub PAGE_SIZE
umems
- The feature of umem_offset to create multiple objects inside a umem
is buggy and isn't used anyplace. Thus we can assume all users of the
current API have umem_offset == 0 as well
Provide a new page size calculator that limits the DMA list to the VA
range and enforces umem_offset == 0.
Allow user space to specify the page sizes which it can accept, this
bitmap must be derived from the intended use of the umem, based on
per-usage HW limitations.
Link: https://lore.kernel.org/r/20210304130501.1102577-4-leon@kernel.org
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
7610ab57de