drm/i915/gem: Fix Virtual Memory mapping boundaries calculation

Calculating the size of the mapped area as the lesser value
between the requested size and the actual size does not consider
the partial mapping offset. This can cause page fault access.

Fix the calculation of the starting and ending addresses, the
total size is now deduced from the difference between the end and
start addresses.

Additionally, the calculations have been rewritten in a clearer
and more understandable form.

Fixes: c58305af1835 ("drm/i915: Use remap_io_mapping() to prefault all PTE in a single pass")
Reported-by: Jann Horn <[email protected]>
Co-developed-by: Chris Wilson <[email protected]>
Signed-off-by: Chris Wilson <[email protected]>
Signed-off-by: Andi Shyti <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Matthew Auld <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: <[email protected]> # v4.9+
Reviewed-by: Jann Horn <[email protected]>
Reviewed-by: Jonathan Cavitt <[email protected]>
[Joonas: Add Requires: tag]
Requires: 60a2066c5005 ("drm/i915/gem: Adjust vma offset for framebuffer mmap offset")
Signed-off-by: Joonas Lahtinen <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit 97b6784753da06d9d40232328efc5c5367e53417)
Signed-off-by: Joonas Lahtinen <[email protected]>

0 files changed, 0 insertions, 0 deletions