This is v3 of [1]. This patch is a workaround for performing partial unmaps of a VM region backed
by huge pages. Since these are now disallowed, the patch makes sure unmaps are done on a backing
page-granularity, and then regions untouched by the VM_BIND unmap operation are restored.

A patch series with IGT tests to validate this functionality is found at [2].

Changelog:
v3:
 - Reworked address logic so that prev and next gpuava_op's va's are used in the calculations
   instead of those of the original unmap vma.
 - Got rid of the return struct from get_map_unmap_intervals() and now reckon panthor_vm_map_pages()
   arguments by fiddlign with the gpuva's respective gem object offsets.
 - Use folio_size() instead of folio_order() because the latter implies page sizes from the
   CPU's MMU perspective, rather than that of the GPU.

v2:
 - Fixed bug caused by confusion between semantics of gpu_va prev and next ops boundaries
   and those of the original vma object.
 - Coalesce all unmap operations into a single one.
 - Refactored and simplified code.

[1] https://lore.kernel.org/dri-devel/20251127035021.624045-1-adrian.larumbe@collabora.com/
[2] https://lore.kernel.org/igt-dev/20251213190205.2435793-1-adrian.larumbe@collabora.com/T/#t


Adrián Larumbe (1):
  drm/panthor: Support partial unmaps of huge pages

 drivers/gpu/drm/panthor/panthor_mmu.c | 66 +++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

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2.51.2