linux-kernel - Re: [PATCH v3 2/2] optee: allocate shared memory with alloc_pages

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Date:   Thu, 16 Nov 2023 18:06:47 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     Jens Wiklander <jens.wiklander@...aro.org>
Cc:     linux-kernel@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
        Jerome Forissier <jerome.forissier@...aro.org>,
        Shyam Saini <shyamsaini@...ux.microsoft.com>
Subject: Re: [PATCH v3 2/2] optee: allocate shared memory with alloc_pages_exact()

On Tue, 14 Nov 2023 at 15:22, Jens Wiklander <jens.wiklander@...aro.org> wrote:
>
> Allocate memory to share with the secure using alloc_pages_exact()

s/with the secure using/with the secure world using/

> instead of alloc_pages() for more efficient memory usage.
>
> Signed-off-by: Jens Wiklander <jens.wiklander@...aro.org>
> ---
>  drivers/tee/optee/core.c | 20 +++++++++-----------
>  1 file changed, 9 insertions(+), 11 deletions(-)
>

Apart from nit above, feel free to add:

Reviewed-by: Sumit Garg <sumit.garg@...aro.org>

-Sumit

> diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
> index 38ea2fecfc2e..4a4b03b4fc7d 100644
> --- a/drivers/tee/optee/core.c
> +++ b/drivers/tee/optee/core.c
> @@ -26,10 +26,8 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
>                                                    size_t num_pages,
>                                                    unsigned long start))
>  {
> -       unsigned int order = get_order(size);
> -       unsigned int nr_pages = 1 << order;
> +       size_t nr_pages = roundup(size, PAGE_SIZE) / PAGE_SIZE;
>         struct page **pages;
> -       struct page *page;
>         unsigned int i;
>         int rc = 0;
>
> @@ -37,13 +35,13 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
>          * Ignore alignment since this is already going to be page aligned
>          * and there's no need for any larger alignment.
>          */
> -       page = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
> -       if (!page)
> +       shm->kaddr = alloc_pages_exact(nr_pages * PAGE_SIZE,
> +                                      GFP_KERNEL | __GFP_ZERO);
> +       if (!shm->kaddr)
>                 return -ENOMEM;
>
> -       shm->kaddr = page_address(page);
> -       shm->paddr = page_to_phys(page);
> -       shm->size = PAGE_SIZE << order;
> +       shm->paddr = virt_to_phys(shm->kaddr);
> +       shm->size = nr_pages * PAGE_SIZE;
>
>         pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
>         if (!pages) {
> @@ -52,7 +50,7 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
>         }
>
>         for (i = 0; i < nr_pages; i++)
> -               pages[i] = page + i;
> +               pages[i] = virt_to_page((u8 *)shm->kaddr + i * PAGE_SIZE);
>
>         shm->pages = pages;
>         shm->num_pages = nr_pages;
> @@ -66,7 +64,7 @@ int optee_pool_op_alloc_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
>
>         return 0;
>  err:
> -       free_pages((unsigned long)shm->kaddr, order);
> +       free_pages_exact(shm->kaddr, shm->size);
>         shm->kaddr = NULL;
>         return rc;
>  }
> @@ -77,7 +75,7 @@ void optee_pool_op_free_helper(struct tee_shm_pool *pool, struct tee_shm *shm,
>  {
>         if (shm_unregister)
>                 shm_unregister(shm->ctx, shm);
> -       free_pages((unsigned long)shm->kaddr, get_order(shm->size));
> +       free_pages_exact(shm->kaddr, shm->size);
>         shm->kaddr = NULL;
>         kfree(shm->pages);
>         shm->pages = NULL;
> --
> 2.34.1
>