On Mon, Aug 24, 2020 at 02:11:25PM -0700, John Hubbard wrote:
This code was using get_user_pages*(), in a "Case 2" scenario (DMA/RDMA), using the categorization from [1]. That means that it's time to convert the get_user_pages*() + put_page() calls to pin_user_pages*() + unpin_user_pages() calls.
Factor out a new, small release_registered_pages() function, in order to consolidate the logic for discerning between TEE_SHM_USER_MAPPED and TEE_SHM_KERNEL_MAPPED pages. This also absorbs the kfree() call that is also required there.
There is some helpful background in [2]: basically, this is a small part of fixing a long-standing disconnect between pinning pages, and file systems' use of those pages.
[1] Documentation/core-api/pin_user_pages.rst
[2] "Explicit pinning of user-space pages": https://lwn.net/Articles/807108/
Cc: Jens Wiklander jens.wiklander@linaro.org Cc: Sumit Semwal sumit.semwal@linaro.org Cc: tee-dev@lists.linaro.org Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Signed-off-by: John Hubbard jhubbard@nvidia.com
OK, one more try, this time actually handling the _USER_MAPPED vs. _KERNEL_MAPPED pages!
thanks, John Hubbard NVIDIA
Looks good and it works too! :-) I've tested it on my Hikey board with the OP-TEE test suite. I'm picking this up.
Thanks, Jens