RE: [EXT] Re: [PATCH v2 4/5] firmware: imx: add driver for NXP EdgeLock Enclave

[Pankaj Gupta <pankaj.gupta@nxp.com>]

> -----Original Message-----
> From: Sascha Hauer <s.hauer@pengutronix.de>
> Sent: Friday, May 24, 2024 4:04 PM
> To: Pankaj Gupta <pankaj.gupta@nxp.com>
> Cc: Jonathan Corbet <corbet@lwn.net>; Rob Herring <robh+dt@kernel.org>;
> Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>; Conor Dooley
> <conor+dt@kernel.org>; Shawn Guo <shawnguo@kernel.org>; Pengutronix
> Kernel Team <kernel@pengutronix.de>; Fabio Estevam
> <festevam@gmail.com>; Rob Herring <robh@kernel.org>; Krzysztof Kozlowski
> <krzk+dt@kernel.org>; linux-doc@vger.kernel.org; linux-
> kernel@vger.kernel.org; devicetree@vger.kernel.org; imx@lists.linux.dev;
> linux-arm-kernel@lists.infradead.org
> Subject: [EXT] Re: [PATCH v2 4/5] firmware: imx: add driver for NXP EdgeLock
> Enclave
>
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> On Thu, May 23, 2024 at 04:19:35PM +0530, Pankaj Gupta wrote:
> > NXP hardware IP(s) for secure-enclaves like Edgelock Enclave(ELE), are
> > embedded in the SoC to support the features like HSM, SHE & V2X, using
> > message based communication interface.
> >
> > The secure enclave FW communicates on a dedicated messaging unit(MU)
> > based interface(s) with application core, where kernel is running.
> > It exists on specific i.MX processors. e.g. i.MX8ULP, i.MX93.
> >
> > This patch adds the driver for communication interface to
> > secure-enclave, for exchanging messages with NXP secure enclave HW
> > IP(s) like EdgeLock Enclave (ELE) from Kernel-space, used by kernel
> > management layers like
> > - DM-Crypt.
> >
> > Signed-off-by: Pankaj Gupta <pankaj.gupta@nxp.com>
> > ---
> >  drivers/firmware/imx/Kconfig        |  12 +
> >  drivers/firmware/imx/Makefile       |   2 +
> >  drivers/firmware/imx/ele_base_msg.c | 286 +++++++++++++++++++
> > drivers/firmware/imx/ele_base_msg.h |  92 +++++++
> >  drivers/firmware/imx/ele_common.c   | 239 ++++++++++++++++
> >  drivers/firmware/imx/ele_common.h   |  43 +++
> >  drivers/firmware/imx/se_ctrl.c      | 531
> ++++++++++++++++++++++++++++++++++++
> >  drivers/firmware/imx/se_ctrl.h      |  99 +++++++
> >  include/linux/firmware/imx/se_api.h |  14 +
> >  9 files changed, 1318 insertions(+)
> >
>
> > +static int se_probe_if_cleanup(struct platform_device *pdev) {
> > +     struct device *dev = &pdev->dev;
> > +     struct se_if_priv *priv;
> > +     int ret = 0;
> > +
> > +     priv = dev_get_drvdata(dev);
> > +     if (!priv) {
> > +             ret = 0;
> > +             dev_dbg(dev, "SE-MU Priv data is NULL;");
> > +             return ret;
> > +     }
> > +
> > +     if (priv->tx_chan)
> > +             mbox_free_channel(priv->tx_chan);
> > +     if (priv->rx_chan)
> > +             mbox_free_channel(priv->rx_chan);
> > +
> > +     /* free the buffer in se remove, previously allocated
> > +      * in se probe to store encrypted IMEM
> > +      */
> > +     if (priv->imem.buf) {
> > +             dmam_free_coherent(dev,
> > +                                ELE_IMEM_SIZE,
> > +                                priv->imem.buf,
> > +                                priv->imem.phyaddr);
> > +             priv->imem.buf = NULL;
> > +     }
> > +
> > +     if (priv->flags & RESERVED_DMA_POOL) {
> > +             of_reserved_mem_device_release(dev);
>
> You can call this unconditionally, no need to keep track if you called
> of_reserved_mem_device_init() successfully.

But it will not be called for each SoC.
The memory is not reserved for i.MX95 platforms.
This is required.

>
> > +
> > +static int se_if_probe(struct platform_device *pdev) {
> > +     struct imx_se_node_info_list *info_list;
> > +     struct device *dev = &pdev->dev;
> > +     struct imx_se_node_info *info;
> > +     struct se_if_priv *priv;
> > +     u32 idx;
> > +     int ret;
> > +
> > +     if (of_property_read_u32(dev->of_node, "reg", &idx)) {
> > +             ret = -EINVAL;
> > +             goto exit;
> > +     }
> > +
> > +     info_list = (struct imx_se_node_info_list *)
> > +                     device_get_match_data(dev);
> > +     info = get_imx_se_node_info(info_list, idx);
> > +
> > +     priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > +     if (!priv) {
> > +             ret = -ENOMEM;
> > +             goto exit;
> > +     }
> > +
> > +     dev_set_drvdata(dev, priv);
> > +
> > +     /* Mailbox client configuration */
> > +     priv->se_mb_cl.dev              = dev;
> > +     priv->se_mb_cl.tx_block         = false;
> > +     priv->se_mb_cl.knows_txdone     = true;
> > +     priv->se_mb_cl.rx_callback      = se_if_rx_callback;
> > +
> > +     ret = se_if_request_channel(dev, &priv->tx_chan,
> > +                     &priv->se_mb_cl, info->mbox_tx_name);
> > +     if (ret)
> > +             goto exit;
> > +
> > +     ret = se_if_request_channel(dev, &priv->rx_chan,
> > +                     &priv->se_mb_cl, info->mbox_rx_name);
> > +     if (ret)
> > +             goto exit;
> > +
> > +     priv->dev = dev;
> > +     priv->info = info;
> > +
> > +     /* Initialize the mutex. */
> > +     mutex_init(&priv->se_if_lock);
> > +     mutex_init(&priv->se_if_cmd_lock);
> > +
> > +     priv->cmd_receiver_dev = NULL;
> > +     priv->waiting_rsp_dev = NULL;
> > +     priv->max_dev_ctx = info->max_dev_ctx;
> > +     priv->cmd_tag = info->cmd_tag;
> > +     priv->rsp_tag = info->rsp_tag;
> > +     priv->mem_pool_name = info->pool_name;
> > +     priv->success_tag = info->success_tag;
> > +     priv->base_api_ver = info->base_api_ver;
> > +     priv->fw_api_ver = info->fw_api_ver;
> > +
> > +     init_completion(&priv->done);
> > +     spin_lock_init(&priv->lock);
> > +
> > +     if (info->reserved_dma_ranges) {
> > +             ret = of_reserved_mem_device_init(dev);
> > +             if (ret) {
> > +                     dev_err(dev,
> > +                             "failed to init reserved memory region %d\n",
> > +                             ret);
> > +                     priv->flags &= (~RESERVED_DMA_POOL);
> > +                     goto exit;
> > +             }
> > +             priv->flags |= RESERVED_DMA_POOL;
> > +     }
>
> Can't this be optional? Why do you need to reserve memory in the device tree
> for it?
>
No, on i.MX8ULP, there is specific reserved memory region that is accessible by secure-enclave.

> Sascha
>
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