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References: <20220114150824.3578829-1-jens.wiklander@linaro.org> <20220114150824.3578829-12-jens.wiklander@linaro.org>
In-Reply-To: <20220114150824.3578829-12-jens.wiklander@linaro.org>
From:   Sumit Garg <sumit.garg@linaro.org>
Date:   Thu, 20 Jan 2022 17:21:12 +0530
Message-ID: <CAFA6WYMQX_e4JKugQFV=87Wvvo2HAfpWLHHK2_MShGBqHBvh-A@mail.gmail.com>
Subject: Re: [PATCH v2 11/12] tee: replace tee_shm_register()
To:     Jens Wiklander <jens.wiklander@linaro.org>
Cc:     linux-kernel@vger.kernel.org, op-tee@lists.trustedfirmware.org,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>,
        Rijo Thomas <Rijo-john.Thomas@amd.com>,
        David Howells <dhowells@redhat.com>,
        Tyler Hicks <tyhicks@linux.microsoft.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, 14 Jan 2022 at 20:38, Jens Wiklander <jens.wiklander@linaro.org> wrote:
>
> tee_shm_register() is replaced by the previously introduced functions
> tee_shm_register_user_buf() and tee_shm_register_kernel_buf().
>
> Since there are not external callers left we can remove tee_shm_register()
> and refactor the remains.
>
> Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
> ---
>  drivers/tee/tee_shm.c   | 157 +++++++++++++++++++++++-----------------
>  include/linux/tee_drv.h |  11 ---
>  2 files changed, 91 insertions(+), 77 deletions(-)
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 6a1dbce75616..fe3e5977dd7c 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -12,17 +12,43 @@
>  #include <linux/uio.h>
>  #include "tee_private.h"
>
> +static void shm_put_kernel_pages(struct page **pages, unsigned long npages)
> +{
> +       unsigned long n;

nit: Can we have a consistent prototype for the number of pages?
size_t as used by struct tee_shm or unsigned long? Same holds true for
variables below as well: npages, page_count, num_pages, n.

> +
> +       for (n = 0; n < npages; n++)
> +               put_page(pages[n]);
> +}
> +
> +static int shm_get_kernel_pages(unsigned long start, int page_count,
> +                               struct page **pages)
> +{
> +       struct kvec *kiov;
> +       unsigned int n;
> +       int rc;
> +
> +       kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> +       if (!kiov)
> +               return -ENOMEM;
> +
> +       for (n = 0; n < page_count; n++) {
> +               kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> +               kiov[n].iov_len = PAGE_SIZE;
> +       }
> +
> +       rc = get_kernel_pages(kiov, page_count, 0, pages);
> +       kfree(kiov);
> +
> +       return rc;
> +}
> +
>  static void release_registered_pages(struct tee_shm *shm)
>  {
>         if (shm->pages) {
> -               if (shm->flags & TEE_SHM_USER_MAPPED) {
> +               if (shm->flags & TEE_SHM_USER_MAPPED)
>                         unpin_user_pages(shm->pages, shm->num_pages);
> -               } else {
> -                       size_t n;
> -
> -                       for (n = 0; n < shm->num_pages; n++)
> -                               put_page(shm->pages[n]);
> -               }
> +               else
> +                       shm_put_kernel_pages(shm->pages, shm->num_pages);
>
>                 kfree(shm->pages);
>         }
> @@ -191,28 +217,24 @@ struct tee_shm *tee_shm_alloc_priv_kernel_buf(struct tee_context *ctx,
>  }
>  EXPORT_SYMBOL_GPL(tee_shm_alloc_priv_kernel_buf);
>
> -struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> -                                size_t length, u32 flags)
> +static struct tee_shm *
> +register_shm_helper(struct tee_context *ctx, unsigned long addr,
> +                   size_t length, u32 flags, int id)
>  {
>         struct tee_device *teedev = ctx->teedev;
> -       const u32 req_user_flags = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED;
> -       const u32 req_kernel_flags = TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED;
>         struct tee_shm *shm;
> +       unsigned long start;
> +       int num_pages;
>         void *ret;
>         int rc;
> -       int num_pages;
> -       unsigned long start;
> -
> -       if (flags != req_user_flags && flags != req_kernel_flags)
> -               return ERR_PTR(-ENOTSUPP);
>
>         if (!tee_device_get(teedev))
>                 return ERR_PTR(-EINVAL);
>
>         if (!teedev->desc->ops->shm_register ||
>             !teedev->desc->ops->shm_unregister) {
> -               tee_device_put(teedev);
> -               return ERR_PTR(-ENOTSUPP);
> +               ret = ERR_PTR(-ENOTSUPP);

Checkpatch warns about this error code:

WARNING: ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP
#104: FILE: drivers/tee/tee_shm.c:236:
+ ret = ERR_PTR(-ENOTSUPP);

> +               goto err_dev_put;
>         }
>
>         teedev_ctx_get(ctx);
> @@ -220,13 +242,13 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
>         shm = kzalloc(sizeof(*shm), GFP_KERNEL);
>         if (!shm) {
>                 ret = ERR_PTR(-ENOMEM);
> -               goto err;
> +               goto err_ctx_put;
>         }
>
>         refcount_set(&shm->refcount, 1);
> -       shm->flags = flags | TEE_SHM_REGISTER;
> +       shm->flags = flags;
>         shm->ctx = ctx;
> -       shm->id = -1;
> +       shm->id = id;
>         addr = untagged_addr(addr);
>         start = rounddown(addr, PAGE_SIZE);
>         shm->offset = addr - start;
> @@ -235,71 +257,45 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
>         shm->pages = kcalloc(num_pages, sizeof(*shm->pages), GFP_KERNEL);
>         if (!shm->pages) {
>                 ret = ERR_PTR(-ENOMEM);
> -               goto err;
> +               goto err_free_shm;
>         }
>
> -       if (flags & TEE_SHM_USER_MAPPED) {
> +       if (flags & TEE_SHM_USER_MAPPED)
>                 rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
>                                          shm->pages);
> -       } else {
> -               struct kvec *kiov;
> -               int i;
> -
> -               kiov = kcalloc(num_pages, sizeof(*kiov), GFP_KERNEL);
> -               if (!kiov) {
> -                       ret = ERR_PTR(-ENOMEM);
> -                       goto err;
> -               }
> -
> -               for (i = 0; i < num_pages; i++) {
> -                       kiov[i].iov_base = (void *)(start + i * PAGE_SIZE);
> -                       kiov[i].iov_len = PAGE_SIZE;
> -               }
> -
> -               rc = get_kernel_pages(kiov, num_pages, 0, shm->pages);
> -               kfree(kiov);
> -       }
> +       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);
> -               goto err;
> -       }
> -
> -       mutex_lock(&teedev->mutex);
> -       shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
> -       mutex_unlock(&teedev->mutex);
> -
> -       if (shm->id < 0) {
> -               ret = ERR_PTR(shm->id);
> -               goto err;
> +               goto err_put_shm_pages;
>         }
>
>         rc = teedev->desc->ops->shm_register(ctx, shm, shm->pages,
>                                              shm->num_pages, start);
>         if (rc) {
>                 ret = ERR_PTR(rc);
> -               goto err;
> +               goto err_put_shm_pages;
>         }
>
>         return shm;
> -err:
> -       if (shm) {
> -               if (shm->id >= 0) {
> -                       mutex_lock(&teedev->mutex);
> -                       idr_remove(&teedev->idr, shm->id);
> -                       mutex_unlock(&teedev->mutex);
> -               }
> -               release_registered_pages(shm);
> -       }
> +err_put_shm_pages:
> +       if (flags & TEE_SHM_USER_MAPPED)
> +               unpin_user_pages(shm->pages, shm->num_pages);
> +       else
> +               shm_put_kernel_pages(shm->pages, shm->num_pages);
> +       kfree(shm->pages);
> +err_free_shm:
>         kfree(shm);
> +err_ctx_put:
>         teedev_ctx_put(ctx);
> +err_dev_put:
>         tee_device_put(teedev);
>         return ret;
>  }
> -EXPORT_SYMBOL_GPL(tee_shm_register);
>
>  /**
>   * tee_shm_register_user_buf() - Register a userspace shared memory buffer
> @@ -312,8 +308,36 @@ EXPORT_SYMBOL_GPL(tee_shm_register);
>  struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,
>                                           unsigned long addr, size_t length)
>  {
> -       return tee_shm_register(ctx, addr, length,
> -                               TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED);
> +       u32 f = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED | TEE_SHM_REGISTER;

nit: I would prefer to write variable name as "flags" for clarity.

> +       struct tee_device *teedev = ctx->teedev;
> +       struct tee_shm *shm;
> +       void *ret;
> +       int id;
> +
> +       mutex_lock(&teedev->mutex);
> +       id = idr_alloc(&teedev->idr, NULL, 1, 0, GFP_KERNEL);
> +       mutex_unlock(&teedev->mutex);
> +

nit: redundant extra line.

> +       if (id < 0)
> +               return ERR_PTR(id);
> +
> +       shm = register_shm_helper(ctx, addr, length, f, id);
> +       if (IS_ERR(shm)) {
> +               mutex_lock(&teedev->mutex);
> +               idr_remove(&teedev->idr, id);
> +               mutex_unlock(&teedev->mutex);
> +               return shm;
> +       }
> +
> +       mutex_lock(&teedev->mutex);
> +       ret = idr_replace(&teedev->idr, shm, id);
> +       mutex_unlock(&teedev->mutex);
> +       if (IS_ERR(ret)) {
> +               tee_shm_free(shm);
> +               return ret;
> +       }
> +
> +       return shm;
>  }
>  EXPORT_SYMBOL_GPL(tee_shm_register_user_buf);
>
> @@ -330,8 +354,9 @@ EXPORT_SYMBOL_GPL(tee_shm_register_user_buf);
>  struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx,
>                                             void *addr, size_t length)
>  {
> -       return tee_shm_register(ctx, (unsigned long)addr, length,
> -                               TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED);
> +       u32 f = TEE_SHM_REGISTER | TEE_SHM_KERNEL_MAPPED;

Ditto.

-Sumit

> +
> +       return register_shm_helper(ctx, (unsigned long)addr, length, f, -1);
>  }
>  EXPORT_SYMBOL_GPL(tee_shm_register_kernel_buf);
>
> diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> index 029c9a0590cc..e4f32885e273 100644
> --- a/include/linux/tee_drv.h
> +++ b/include/linux/tee_drv.h
> @@ -278,17 +278,6 @@ struct tee_shm *tee_shm_alloc_priv_kernel_buf(struct tee_context *ctx,
>                                               size_t size);
>  struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size);
>
> -/**
> - * tee_shm_register() - Register shared memory buffer
> - * @ctx:       Context that registers the shared memory
> - * @addr:      Address is userspace of the shared buffer
> - * @length:    Length of the shared buffer
> - * @flags:     Flags setting properties for the requested shared memory.
> - *
> - * @returns a pointer to 'struct tee_shm'
> - */
> -struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> -                                size_t length, u32 flags);
>  struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,
>                                           unsigned long addr, size_t length);
>  struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx,
> --
> 2.31.1
>