RDMA/umem: Fix ib_umem_find_best_pgsz() for mappings that cross a page boundary

It is possible for a single SGL to span an aligned boundary, eg if the SGL
is

  61440 -> 90112

Then the length is 28672, which currently limits the block size to
32k. With a 32k page size the two covering blocks will be:

  32768->65536 and 65536->98304

However, the correct answer is a 128K block size which will span the whole
28672 bytes in a single block.

Instead of limiting based on length figure out which high IOVA bits don't
change between the start and end addresses. That is the highest useful
page size.

Fixes: 4a35339958f1 ("RDMA/umem: Add API to find best driver supported page size in an MR")
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Leon Romanovsky <[email protected]>
Reviewed-by: Shiraz Saleem <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

0 files changed, 0 insertions, 0 deletions