video: tegra: nvmap: support inserting pages on unreserve

video: tegra: nvmap: support inserting pages on unreserve

Some times it is beneficial to insert pages into vma on unreserve.
This avoids page fault overhead for any accesses later. If user space
knows apriori which regions of a group of handles will be accessed for
sure, user space can pass relevant information with this new
NVMAP_INSERT_PAGE_ON_UNRESERVE option to reserve ioctl call.

Mark pages as writable, else write accesses after read fault nullifying the
purpose of the option.

Bug 200092803

Change-Id: Id44502b9a5d890d24f221e38c6ae781584ce7ace
Signed-off-by: Sri Krishna chowdary <schowdary@nvidia.com>
Reviewed-on: http://git-master/r/781602
GVS: Gerrit_Virtual_Submit
Reviewed-by: Krishna Reddy <vdumpa@nvidia.com>