Re: [Tee-dev] [PATCH v3] optee: allow to work without static shared memory

[Sumit Garg <sumit.garg@linaro.org>]

Hi Volodymyr, Jens,

On Mon, 11 Mar 2019 at 18:34, Volodymyr Babchuk
<Volodymyr_Babchuk@epam.com> wrote:
>
> From: Volodymyr Babchuk <vlad.babchuk@gmail.com>
>
> On virtualized systems it is possible that OP-TEE will provide
> only dynamic shared memory support. So it is fine to boot
> without static SHM enabled if dymanic one is supported.
>
> Signed-off-by: Volodymyr Babchuk <vlad.babchuk@gmail.com>
> ---

Is this patch well tested?

This patch seems to broke "tee_shm_alloc()" API for all kernel
internal / user-space clients in case dynamic shared memory is enabled
in OP-TEE (capability: OPTEE_SMC_SEC_CAP_DYNAMIC_SHM is set).

How are kernel buffers allocated from "dmabuf_mgr" as per this patch
registered with OP-TEE?

Note here that "priv_mgr" seems to work well as OP-TEE provides a hook
to map the buffers returned during RPC calls into registered shm
space.

I think the correct way to enable intended feature as per description
of the patch would be to add an additional call to
"optee_shm_register()" during allocation from "dmabuf_mgr". So I have
proposed a fix patch here [1]. Please have a look.

[1] https://lkml.org/lkml/2019/10/31/382

Regards,
Sumit

>
>  Changes from V2:
>   - rebased onto upstream
>
>  drivers/tee/optee/core.c | 80 ++++++++++++++++++++++++----------------
>  1 file changed, 49 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
> index 0842b6e6af82..48963eab32f5 100644
> --- a/drivers/tee/optee/core.c
> +++ b/drivers/tee/optee/core.c
> @@ -419,9 +419,35 @@ static bool optee_msg_exchange_capabilities(optee_invoke_fn *invoke_fn,
>         return true;
>  }
>
> +static struct tee_shm_pool *optee_config_dyn_shm(void)
> +{
> +       struct tee_shm_pool_mgr *priv_mgr;
> +       struct tee_shm_pool_mgr *dmabuf_mgr;
> +       void *rc;
> +
> +       rc = optee_shm_pool_alloc_pages();
> +       if (IS_ERR(rc))
> +               return rc;
> +       priv_mgr = rc;
> +
> +       rc = optee_shm_pool_alloc_pages();
> +       if (IS_ERR(rc)) {
> +               tee_shm_pool_mgr_destroy(priv_mgr);
> +               return rc;
> +       }
> +       dmabuf_mgr = rc;
> +
> +       rc = tee_shm_pool_alloc(priv_mgr, dmabuf_mgr);
> +       if (IS_ERR(rc)) {
> +               tee_shm_pool_mgr_destroy(priv_mgr);
> +               tee_shm_pool_mgr_destroy(dmabuf_mgr);
> +       }
> +
> +       return rc;
> +}
> +
>  static struct tee_shm_pool *
> -optee_config_shm_memremap(optee_invoke_fn *invoke_fn, void **memremaped_shm,
> -                         u32 sec_caps)
> +optee_config_shm_memremap(optee_invoke_fn *invoke_fn, void **memremaped_shm)
>  {
>         union {
>                 struct arm_smccc_res smccc;
> @@ -436,10 +462,11 @@ optee_config_shm_memremap(optee_invoke_fn *invoke_fn, void **memremaped_shm,
>         struct tee_shm_pool_mgr *priv_mgr;
>         struct tee_shm_pool_mgr *dmabuf_mgr;
>         void *rc;
> +       const int sz = OPTEE_SHM_NUM_PRIV_PAGES * PAGE_SIZE;
>
>         invoke_fn(OPTEE_SMC_GET_SHM_CONFIG, 0, 0, 0, 0, 0, 0, 0, &res.smccc);
>         if (res.result.status != OPTEE_SMC_RETURN_OK) {
> -               pr_info("shm service not available\n");
> +               pr_err("static shm service not available\n");
>                 return ERR_PTR(-ENOENT);
>         }
>
> @@ -465,28 +492,15 @@ optee_config_shm_memremap(optee_invoke_fn *invoke_fn, void **memremaped_shm,
>         }
>         vaddr = (unsigned long)va;
>
> -       /*
> -        * If OP-TEE can work with unregistered SHM, we will use own pool
> -        * for private shm
> -        */
> -       if (sec_caps & OPTEE_SMC_SEC_CAP_DYNAMIC_SHM) {
> -               rc = optee_shm_pool_alloc_pages();
> -               if (IS_ERR(rc))
> -                       goto err_memunmap;
> -               priv_mgr = rc;
> -       } else {
> -               const size_t sz = OPTEE_SHM_NUM_PRIV_PAGES * PAGE_SIZE;
> -
> -               rc = tee_shm_pool_mgr_alloc_res_mem(vaddr, paddr, sz,
> -                                                   3 /* 8 bytes aligned */);
> -               if (IS_ERR(rc))
> -                       goto err_memunmap;
> -               priv_mgr = rc;
> -
> -               vaddr += sz;
> -               paddr += sz;
> -               size -= sz;
> -       }
> +       rc = tee_shm_pool_mgr_alloc_res_mem(vaddr, paddr, sz,
> +                                           3 /* 8 bytes aligned */);
> +       if (IS_ERR(rc))
> +               goto err_memunmap;
> +       priv_mgr = rc;
> +
> +       vaddr += sz;
> +       paddr += sz;
> +       size -= sz;
>
>         rc = tee_shm_pool_mgr_alloc_res_mem(vaddr, paddr, size, PAGE_SHIFT);
>         if (IS_ERR(rc))
> @@ -552,7 +566,7 @@ static optee_invoke_fn *get_invoke_func(struct device_node *np)
>  static struct optee *optee_probe(struct device_node *np)
>  {
>         optee_invoke_fn *invoke_fn;
> -       struct tee_shm_pool *pool;
> +       struct tee_shm_pool *pool = ERR_PTR(-EINVAL);
>         struct optee *optee = NULL;
>         void *memremaped_shm = NULL;
>         struct tee_device *teedev;
> @@ -581,13 +595,17 @@ static struct optee *optee_probe(struct device_node *np)
>         }
>
>         /*
> -        * We have no other option for shared memory, if secure world
> -        * doesn't have any reserved memory we can use we can't continue.
> +        * Try to use dynamic shared memory if possible
>          */
> -       if (!(sec_caps & OPTEE_SMC_SEC_CAP_HAVE_RESERVED_SHM))
> -               return ERR_PTR(-EINVAL);
> +       if (sec_caps & OPTEE_SMC_SEC_CAP_DYNAMIC_SHM)
> +               pool = optee_config_dyn_shm();
> +
> +       /*
> +        * If dynamic shared memory is not available or failed - try static one
> +        */
> +       if (IS_ERR(pool) && (sec_caps & OPTEE_SMC_SEC_CAP_HAVE_RESERVED_SHM))
> +               pool = optee_config_shm_memremap(invoke_fn, &memremaped_shm);
>
> -       pool = optee_config_shm_memremap(invoke_fn, &memremaped_shm, sec_caps);
>         if (IS_ERR(pool))
>                 return (void *)pool;
>
> --
> 2.21.0
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