Re: [PATCH] tee: Use iov_iter to better support shared buffer registration

Hi Jens,

On 11/27/23 13:12, Jens Wiklander wrote:

On Fri, Nov 24, 2023 at 6:34 PM Arnaud Pouliquen arnaud.pouliquen@foss.st.com wrote:

...

It is not possible to register buffers allocated with vmalloc. Use iov_iter and associated helper functions to manage the page registration for all type of memories.

Suggested-by: Christoph Hellwig hch@infradead.org Signed-off-by: Arnaud Pouliquen arnaud.pouliquen@foss.st.com

---

The support of buffer registration allocated with vmalloc is no more available since c83900393aa1 ("tee: Remove vmalloc page support").

This patch is an alternative to a revert and resulted from a discussion with Christopher Hellwig [1].

This patch has been tested using xtest tool in optee qemu environment [2] and using the series related to the remoteproc tee that should be proposed soon [3].

References: [1] https://lore.kernel.org/linux-arm-kernel/18a8528d-7d9d-6ed0-0045-5ee47dd39fb... [2] https://optee.readthedocs.io/en/latest/building/devices/qemu.html#build-inst... [3] https://lore.kernel.org/linux-arm-kernel/18a8528d-7d9d-6ed0-0045-5ee47dd39fb...

---

drivers/tee/tee_shm.c | 72 +++++++++++++++++++++++-------------------- 1 file changed, 38 insertions(+), 34 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index 673cf0359494..0bb47ffd049a 100644 --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -22,23 +22,13 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count) put_page(pages[n]); }

-static int shm_get_kernel_pages(unsigned long start, size_t page_count,

•                           struct page **pages)
  

+static void shm_get_kernel_pages(struct page **pages, size_t page_count) {

•   struct page *page;
    size_t n;
  
  

•   if (WARN_ON_ONCE(is_vmalloc_addr((void *)start) ||
  

•                    is_kmap_addr((void *)start)))
  

•           return -EINVAL;
  

•   page = virt_to_page((void *)start);
  

•   for (n = 0; n < page_count; n++) {
  

•           pages[n] = page + n;
  

•   /* iov_iter_extract_kvec_pages does not get reference on the pages, get a pin on them. */
  

•   for (n = 0; n < page_count; n++)
            get_page(pages[n]);
  

•   }
  

•   return page_count;
  

}

static void release_registered_pages(struct tee_shm *shm) @@ -214,13 +204,12 @@ struct tee_shm *tee_shm_alloc_priv_buf(struct tee_context *ctx, size_t size) EXPORT_SYMBOL_GPL(tee_shm_alloc_priv_buf);

static struct tee_shm * -register_shm_helper(struct tee_context *ctx, unsigned long addr,

•               size_t length, u32 flags, int id)
  

+register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags, int id) { struct tee_device *teedev = ctx->teedev; struct tee_shm *shm;

•   unsigned long start;
  

•   size_t num_pages;
  

•   unsigned long start, addr;
  

•   size_t num_pages, length, len, off;
    void *ret;
    int rc;
  
  

@@ -245,31 +234,31 @@ register_shm_helper(struct tee_context *ctx, unsigned long addr, shm->flags = flags; shm->ctx = ctx; shm->id = id;

•   addr = untagged_addr(addr);
  

•   addr = (unsigned long)iter_iov_addr(iter);
  

•   length = iter_iov_len(iter);
    start = rounddown(addr, PAGE_SIZE);
  

•   shm->offset = addr - start;
  

•   shm->size = length;
  

•   num_pages = (roundup(addr + length, PAGE_SIZE) - start) / PAGE_SIZE;
  

•   num_pages = iov_iter_npages(iter, INT_MAX);
  

•   if (!num_pages) {
  

•           ret = ERR_PTR(-ENOMEM);
  

•           goto err_ctx_put;
  

•   }
  

•   shm->pages = kcalloc(num_pages, sizeof(*shm->pages), GFP_KERNEL);
    if (!shm->pages) {
            ret = ERR_PTR(-ENOMEM);
            goto err_free_shm;
    }
  
  

•   if (flags & TEE_SHM_USER_MAPPED)
  

•           rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
  

•                                    shm->pages);
  

•   else
  

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

•   if (rc > 0)
  

•           shm->num_pages = rc;
  

•   if (rc != num_pages) {
  

•           if (rc >= 0)
  

•                   rc = -ENOMEM;
  

•           ret = ERR_PTR(rc);
  

•   len = iov_iter_extract_pages(iter, &shm->pages, LONG_MAX, num_pages, 0, &off);
  

•   if (len != length) {
  

•           ret = len ? ERR_PTR(len) : ERR_PTR(-ENOMEM);
            goto err_put_shm_pages;
    }
  
  

•   shm->offset = off;
  

•   shm->size = len;
  

•   shm->num_pages = num_pages;
  

•   rc = teedev->desc->ops->shm_register(ctx, shm, shm->pages,
                                         shm->num_pages, start);
    if (rc) {
  

@@ -307,6 +296,8 @@ struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx, u32 flags = TEE_SHM_USER_MAPPED | TEE_SHM_DYNAMIC; struct tee_device *teedev = ctx->teedev; struct tee_shm *shm;

•   struct iovec iov;
  

•   struct iov_iter iter;
    void *ret;
    int id;
  
  

@@ -319,7 +310,10 @@ struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx, if (id < 0) return ERR_PTR(id);

•   shm = register_shm_helper(ctx, addr, length, flags, id);
  

•   iov.iov_base = (void __user *)addr;
  

•   iov.iov_len = length;
  

•   iov_iter_init(&iter, ITER_DEST, &iov, 1, length);
  

•   shm = register_shm_helper(ctx, &iter, flags, id);
    if (IS_ERR(shm)) {
            mutex_lock(&teedev->mutex);
            idr_remove(&teedev->idr, id);
  

@@ -351,9 +345,19 @@ struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx, struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx, void *addr, size_t length) {

•   struct tee_shm *shm;
    u32 flags = TEE_SHM_DYNAMIC;
  

•   struct kvec kvec;
  

•   struct iov_iter iter;
  
  

•   return register_shm_helper(ctx, (unsigned long)addr, length, flags, -1);
  

•   kvec.iov_base = addr;
  

•   kvec.iov_len = length;
  

•   iov_iter_kvec(&iter, ITER_SOURCE, &kvec, 1, length);
  

Why are you using ITER_SOURCE? This memory can be both read from and written to.

The reason is just an update I made for a test, that I have forgotten to revert.

I will fix this in V2

Thanks! Arnaud

...

•   shm = register_shm_helper(ctx, &iter, flags, -1);
  

•   if (!IS_ERR_OR_NULL(shm))
  

IS_ERR should be enough.

Cheers, Jens

...

•           shm_get_kernel_pages(shm->pages, shm->num_pages);
  

•   return shm;
  

} EXPORT_SYMBOL_GPL(tee_shm_register_kernel_buf);

-- 2.25.1