Re: [Tee-dev] [PATCH v2] tee: convert get_user_pages() --> pin_user_pages()

Hi John,

On Tue, May 26, 2020 at 1:32 AM John Hubbard jhubbard@nvidia.com 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.

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

---

Hi,

This fixes the typo ("convert convert") in the subject line, but otherwise no changes.

thanks, John Hubbard NVIDIA

drivers/tee/tee_shm.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-)

Looks good. I've tested this on a HiKey 620 board, no regressions. I'm picking up this patch.

Thanks, Jens

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index bd679b72bd05..7dffc42d8d5a 100644 --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -31,16 +31,13 @@ static void tee_shm_release(struct tee_shm *shm)

            poolm->ops->free(poolm, shm);
    } else if (shm->flags & TEE_SHM_REGISTER) {

•           size_t n;
            int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);
  
            if (rc)
                    dev_err(teedev->dev.parent,
                            "unregister shm %p failed: %d", shm, rc);
  
  

•           for (n = 0; n < shm->num_pages; n++)
  

•                   put_page(shm->pages[n]);
  

•           unpin_user_pages(shm->pages, shm->num_pages);
            kfree(shm->pages);
    }
  
  

@@ -226,7 +223,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr, goto err; }

•   rc = get_user_pages_fast(start, num_pages, FOLL_WRITE, shm->pages);
  

•   rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE, shm->pages);
    if (rc > 0)
            shm->num_pages = rc;
    if (rc != num_pages) {
  

@@ -271,16 +268,13 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr, return shm; err: if (shm) {

•           size_t n;
  

•           if (shm->id >= 0) {
                    mutex_lock(&teedev->mutex);
                    idr_remove(&teedev->idr, shm->id);
                    mutex_unlock(&teedev->mutex);
            }
            if (shm->pages) {
  

•                   for (n = 0; n < shm->num_pages; n++)
  

•                           put_page(shm->pages[n]);
  

•                   unpin_user_pages(shm->pages, shm->num_pages);
                    kfree(shm->pages);
            }
    }
  

-- 2.26.2