linux-kernel - Re: [PATCH 5/9] firmware: arm_ffa: Use FFA_FEATURES to detect if native versions are supported

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Message-ID: <CAHUa44ETTyP+4ydNZ+A7y_vRuUsfDQtxox1Ox06aM5rcgLgYZA@mail.gmail.com>
Date:   Thu, 1 Sep 2022 10:18:01 +0200
From:   Jens Wiklander <jens.wiklander@...aro.org>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     linux-kernel@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
        Marc Bonnici <marc.bonnici@....com>,
        Achin Gupta <achin.gupta@....com>,
        Valentin Laurent <valentin.laurent@...stonic.com>,
        Lukas Hanel <lukas.hanel@...stonic.com>,
        Coboy Chen <coboy.chen@...iatek.com>
Subject: Re: [PATCH 5/9] firmware: arm_ffa: Use FFA_FEATURES to detect if
 native versions are supported

On Tue, Aug 30, 2022 at 12:07 PM Sudeep Holla <sudeep.holla@....com> wrote:
>
> Currently, the ffa_dev->mode_32bit is use to detect if the native 64-bit
> or 32-bit versions of FF-A ABI needs to be used. However for the FF-A
> memory ABIs, it is not dependent on the ffa_device(i.e. the partition)
> itself, but the partition manager(SPM).
>
> So, the FFA_FEATURES can be use to detect if the native 64bit ABIs are
> supported or not and appropriate calls can be made based on that.
>
> Use FFA_FEATURES to detect if native versions of MEM_LEND or MEM_SHARE
> are implemented and make of the same to use native memory ABIs later on.
>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>  drivers/firmware/arm_ffa/driver.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)

Reviewed-by: Jens Wiklander <jens.wiklander@...aro.org>

>
> diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
> index de94073f4109..5f02b670e964 100644
> --- a/drivers/firmware/arm_ffa/driver.c
> +++ b/drivers/firmware/arm_ffa/driver.c
> @@ -163,6 +163,7 @@ struct ffa_drv_info {
>         struct mutex tx_lock; /* lock to protect Tx buffer */
>         void *rx_buffer;
>         void *tx_buffer;
> +       bool mem_ops_native;
>  };
>
>  static struct ffa_drv_info *drv_info;
> @@ -594,6 +595,13 @@ static int ffa_features(u32 func_feat_id, u32 input_props, u32 *if_props)
>         return 0;
>  }
>
> +static void ffa_set_up_mem_ops_native_flag(void)
> +{
> +       if (!ffa_features(FFA_FN_NATIVE(MEM_LEND), 0, NULL) ||
> +           !ffa_features(FFA_FN_NATIVE(MEM_SHARE), 0, NULL))
> +               drv_info->mem_ops_native = true;
> +}
> +
>  static u32 ffa_api_version_get(void)
>  {
>         return drv_info->version;
> @@ -635,10 +643,10 @@ static int ffa_sync_send_receive(struct ffa_device *dev,
>  static int
>  ffa_memory_share(struct ffa_device *dev, struct ffa_mem_ops_args *args)
>  {
> -       if (dev->mode_32bit)
> -               return ffa_memory_ops(FFA_MEM_SHARE, args);
> +       if (drv_info->mem_ops_native)
> +               return ffa_memory_ops(FFA_FN_NATIVE(MEM_SHARE), args);
>
> -       return ffa_memory_ops(FFA_FN_NATIVE(MEM_SHARE), args);
> +       return ffa_memory_ops(FFA_MEM_SHARE, args);
>  }
>
>  static int
> @@ -651,10 +659,10 @@ ffa_memory_lend(struct ffa_device *dev, struct ffa_mem_ops_args *args)
>          * however on systems without a hypervisor the responsibility
>          * falls to the calling kernel driver to prevent access.
>          */
> -       if (dev->mode_32bit)
> -               return ffa_memory_ops(FFA_MEM_LEND, args);
> +       if (drv_info->mem_ops_native)
> +               return ffa_memory_ops(FFA_FN_NATIVE(MEM_LEND), args);
>
> -       return ffa_memory_ops(FFA_FN_NATIVE(MEM_LEND), args);
> +       return ffa_memory_ops(FFA_MEM_LEND, args);
>  }
>
>  static const struct ffa_dev_ops ffa_ops = {
> @@ -765,6 +773,8 @@ static int __init ffa_init(void)
>
>         ffa_setup_partitions();
>
> +       ffa_set_up_mem_ops_native_flag();
> +
>         return 0;
>  free_pages:
>         if (drv_info->tx_buffer)
> --
> 2.37.2
>