Message-ID: <4khzl4tak2whgjjedefc2tmcpooe4w4ajxkvpiijohxoljirol@2or5k4jpbb3x>
Date: Mon, 16 Jun 2025 23:34:28 -0500
From: Bjorn Andersson <andersson@...nel.org>
To: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>, 
	Jens Wiklander <jens.wiklander@...aro.org>, Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-stm32@...md-mailman.stormreply.com, linux-arm-kernel@...ts.infradead.org, 
	linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org, op-tee@...ts.trustedfirmware.org, 
	devicetree@...r.kernel.org
Subject: Re: [PATCH v18 2/6] remoteproc: Add TEE support

On Mon, Jun 16, 2025 at 09:55:26AM +0200, Arnaud Pouliquen wrote:
> Add a remoteproc TEE (Trusted Execution Environment) driver that will be
> probed by the TEE bus. If the associated Trusted application is supported
> on the secure part, this driver offers a client interface to load firmware
> by the secure part.
> This firmware could be authenticated by the secure trusted application.
> 
> A specificity of the implementation is that the firmware has to be
> authenticated and optionally decrypted to access the resource table.
> 
> Consequently, the boot sequence is:
> 
> 1) rproc_parse_fw --> rproc_tee_parse_fw
>    remoteproc TEE:
>    - Requests the TEE application to authenticate and load the firmware
>      in the remote processor memories.
>    - Requests the TEE application for the address of the resource table.
>    - Creates a copy of the resource table stored in rproc->cached_table.
> 
> 2) rproc_load_segments --> rproc_tee_load_fw
>    remoteproc TEE:
>    - Requests the TEE application to load the firmware. Nothing is done
>      at the TEE application as the firmware is already loaded.
>    - In case of recovery, the TEE application has to reload the firmware.
> 
> 3) rproc_tee_get_loaded_rsc_table
>    remoteproc TEE requests the TEE application for the address of the
>    resource table.
> 
> 4) rproc_start --> rproc_tee_start
>    - Requests the TEE application to start the remote processor.
> 
> The shutdown sequence is:
> 
> 5) rproc_stop --> rproc_tee_stop
>    - Requests the TEE application to stop the remote processor.
> 
> 6) rproc_tee_release_fw
>    This function is used to request the TEE application to perform actions
>    to return to the initial state on stop or on error during the boot
>    sequence.
> 

I thought these patches were ready to go in now, but as I went through
them in detail once more the locking in this patch caught my attention.
And the kernel-doc is not good.

> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> ---
> Updates vs previous version:
> Fix warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing

Please keep the full change history in each version of your series, it
makes it easier to review.

> ---
>  drivers/remoteproc/Kconfig          |  10 +
>  drivers/remoteproc/Makefile         |   1 +
>  drivers/remoteproc/remoteproc_tee.c | 620 ++++++++++++++++++++++++++++
>  include/linux/remoteproc_tee.h      |  90 ++++
>  4 files changed, 721 insertions(+)
>  create mode 100644 drivers/remoteproc/remoteproc_tee.c
>  create mode 100644 include/linux/remoteproc_tee.h
> 
> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> index 83962a114dc9..e39265d249d9 100644
> --- a/drivers/remoteproc/Kconfig
> +++ b/drivers/remoteproc/Kconfig
> @@ -23,6 +23,16 @@ config REMOTEPROC_CDEV
>  
>  	  It's safe to say N if you don't want to use this interface.
>  
> +config REMOTEPROC_TEE
> +	bool "Remoteproc support by a TEE application"
> +	depends on OPTEE
> +	help
> +	  Support a remote processor that is managed by an application running in a Trusted
> +	  Execution Environment (TEE). This application is responsible for loading the remote
> +	  processor firmware image and managing its lifecycle.
> +
> +	  It's safe to say N if the remote processor is not managed by a TEE.
> +
>  config IMX_REMOTEPROC
>  	tristate "i.MX remoteproc support"
>  	depends on ARCH_MXC
> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> index 1c7598b8475d..a1a5201982d4 100644
> --- a/drivers/remoteproc/Makefile
> +++ b/drivers/remoteproc/Makefile
> @@ -11,6 +11,7 @@ remoteproc-y				+= remoteproc_sysfs.o
>  remoteproc-y				+= remoteproc_virtio.o
>  remoteproc-y				+= remoteproc_elf_loader.o
>  obj-$(CONFIG_REMOTEPROC_CDEV)		+= remoteproc_cdev.o
> +obj-$(CONFIG_REMOTEPROC_TEE)		+= remoteproc_tee.o
>  obj-$(CONFIG_IMX_REMOTEPROC)		+= imx_rproc.o
>  obj-$(CONFIG_IMX_DSP_REMOTEPROC)	+= imx_dsp_rproc.o
>  obj-$(CONFIG_INGENIC_VPU_RPROC)		+= ingenic_rproc.o
> diff --git a/drivers/remoteproc/remoteproc_tee.c b/drivers/remoteproc/remoteproc_tee.c
> new file mode 100644
> index 000000000000..6b610dfa1ee1
> --- /dev/null
> +++ b/drivers/remoteproc/remoteproc_tee.c
> @@ -0,0 +1,620 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) STMicroelectronics 2024

Bump the year, please.

> + * Author: Arnaud Pouliquen <arnaud.pouliquen@...s.st.com>
> + */
> +
> +#include <linux/export.h>
> +#include <linux/firmware.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/remoteproc.h>
> +#include <linux/remoteproc_tee.h>
> +#include <linux/slab.h>
> +#include <linux/tee_drv.h>
> +
> +#define MAX_TEE_PARAM_ARRAY_MEMBER	4
> +
> +/*
> + * Authentication and load of the firmware image in the remote processor memories by the TEE.
> + * After this step the firmware is loaded in destination memories, which can then be locked to
> + * prevent access by Linux.

Wrap lines at 80 characters, if it improves readability you can use up
to 100.

> + *
> + * [in]  params[0].value.a:	remote processor identifier

Here "[in]" is followed by 2 spaces.

> + * [in]	 params[1].memref:	buffer containing a temporary copy of the signed image to load.

Here "[in]" is followed by one tab and one space.

> + */
> +#define TA_RPROC_FW_CMD_LOAD_FW		1
> +
> +/*
> + * Start the remote processor by the TEE
> + *
> + * [in]  params[0].value.a:	remote processor identifier
> + */
> +#define TA_RPROC_FW_CMD_START		2
> +
> +/*
> + * Stop the remote processor by the TEE
> + *
> + * [in]  params[0].value.a:	remote processor identifier
> + */
> +#define TA_RPROC_FW_CMD_STOP		3
> +
> +/*
> + * Return the address of the resource table, or 0 if not found.
> + *
> + * [in]  params[0].value.a:	remote processor identifier
> + * [out]  params[1].value.a:	32bit LSB resource table memory address
> + * [out]  params[1].value.b:	32bit MSB resource table memory address
> + * [out]  params[2].value.a:	32bit LSB resource table memory size
> + * [out]  params[2].value.b:	32bit MSB resource table memory size
> + */
> +#define TA_RPROC_FW_CMD_GET_RSC_TABLE	4
> +
> +/*
> + * Release remote processor firmware images and associated resources.
> + * This command should be used in case an error occurs between the loading of
> + * the firmware images (TA_RPROC_CMD_LOAD_FW) and the starting of the remote
> + * processor (TA_RPROC_CMD_START_FW) or after stopping the remote processor
> + * to release associated resources (TA_RPROC_CMD_STOP_FW).
> + *
> + * [in]  params[0].value.a: Unique 32-bit remote processor identifier

The other 4 commands are defined with "remote processor identifier" as
the first parameter, but this command needs a "unique 32-bit" such
value?

> + */
> +#define TA_RPROC_CMD_RELEASE_FW		6
> +
> +struct rproc_tee_context {
> +	struct list_head	sessions;
> +	struct tee_context	*tee_ctx;
> +	struct device		*dev;
> +};
> +
> +/**
> + * struct rproc_tee - TEE remoteproc structure
> + * @node:		Reference in list
> + * @rproc:		Remoteproc reference
> + * @rproc_id:		Identifier of the target firmware

Everywhere else you say this identifies the remote processor...

> + * @session_id:		TEE session identifier
> + */
> +struct rproc_tee {
> +	struct list_head node;
> +	struct rproc *rproc;
> +	u32 rproc_id;
> +	u32 session_id;
> +};
> +
> +static struct rproc_tee_context rproc_tee_ctx;
> +static DEFINE_SPINLOCK(ctx_lock);
> +
> +static struct rproc_tee *rproc_to_trproc(struct rproc *rproc)
> +{
> +	struct rproc_tee *trproc;
> +
> +	list_for_each_entry(trproc, &rproc_tee_ctx.sessions, node)

You make sure to only modify this list under lock, but here you're
traversing the list without consideration for concurrency.

> +		if (trproc->rproc == rproc)
> +			return trproc;
> +
> +	return NULL;
> +}
> +
> +static void rproc_tee_prepare_args(struct rproc_tee *trproc, int cmd,
> +				   struct tee_ioctl_invoke_arg *arg,
> +				   struct tee_param *param,
> +				   unsigned int num_params)
> +{
> +	memset(arg, 0, sizeof(*arg));
> +	memset(param, 0, MAX_TEE_PARAM_ARRAY_MEMBER * sizeof(*param));
> +
> +	arg->func = cmd;
> +	arg->session = trproc->session_id;
> +	arg->num_params = num_params + 1;
> +
> +	param[0] = (struct tee_param) {
> +		.attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> +		.u.value.a = trproc->rproc_id,
> +	};
> +}
> +
> +/**
> + * rproc_tee_release_fw - Release the firmware for a TEE-based remote processor
> + *
> + * This function invokes the TA_RPROC_CMD_RELEASE_FW TEE client function to release the firmware.
> + * It should only be called when the remoteproc state is RPROC_OFFLINE or RPROC_DETACHED.
> + * The function requests the TEE remoteproc application to release the firmware loaded by
> + * rproc_tee_load_fw(). The request is ignored if the rproc state is RPROC_DETACHED as the
> + * remote processor is still running.
> + *
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + */
> +void rproc_tee_release_fw(struct rproc *rproc)
> +{
> +	struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> +	struct rproc_tee *trproc = rproc_to_trproc(rproc);
> +	struct tee_ioctl_invoke_arg arg;
> +	int ret;
> +
> +	if (!rproc_tee_ctx.dev)

In the (unlikely) event that the tee device is removed this is racy. On
the other hand, the only thing you seem to rely on this "dev" for is
error prints?

> +		return;
> +
> +	if (!trproc)
> +		return;
> +
> +	/*
> +	 * If the remote processor state is RPROC_DETACHED, just ignore the
> +	 * request, as the remote processor is still running.
> +	 */
> +	if (rproc->state == RPROC_DETACHED)
> +		return;
> +
> +	if (rproc->state != RPROC_OFFLINE) {
> +		dev_err(rproc_tee_ctx.dev, "unexpected rproc state: %d\n", rproc->state);
> +		return;
> +	}
> +
> +	rproc_tee_prepare_args(trproc, TA_RPROC_CMD_RELEASE_FW, &arg, param, 0);
> +
> +	ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> +	if (ret < 0 || arg.ret != 0) {
> +		dev_err(rproc_tee_ctx.dev,
> +			"TA_RPROC_CMD_RELEASE_FW invoke failed TEE err: %#x, ret:%d\n",
> +			arg.ret, ret);
> +		ret = -EIO;

ret isn't returned, so there's no reason to assign it here.

> +	}
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_release_fw);
> +
> +/**
> + * rproc_tee_load_fw - Load firmware from TEE application
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @fw: Pointer to the firmware structure containing the firmware data and size
> + *
> + * This function invokes the TA_RPROC_FW_CMD_LOAD_FW TEE client function to load the firmware.
> + * It registers the fw->data as a shared memory region with the TEE, and request the TEE to load
> + * the firmware. This function can be called twice during the remote processor boot, considering
> + * that the TEE application ignores the command if the firmware is already loaded.

"can be called twice"? How does this relate to the TEE application
ignoring the command? How does the client know if the application
ignored it?

> + *
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @fw: Pointer to the firmware structure containing the firmware data and size

https://docs.kernel.org/doc-guide/kernel-doc.html#function-documentation
says function name should have () suffix. Then arguments (here you have
them twice). Then the longer description (for rproc_tee_release_fw() you
have this before arguments).

Also, please keep it within 80 characters.

> + *
> + * Return: 0 on success, or an error code on failure
> + */
> +int rproc_tee_load_fw(struct rproc *rproc, const struct firmware *fw)
> +{
> +	struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> +	struct rproc_tee *trproc = rproc_to_trproc(rproc);
> +	struct tee_ioctl_invoke_arg arg;
> +	struct tee_shm *fw_shm;
> +	int ret;
> +
> +	if (!rproc_tee_ctx.dev)
> +		return -ENODEV;
> +
> +	if (!trproc)
> +		return -EINVAL;
> +
> +	fw_shm = tee_shm_register_kernel_buf(rproc_tee_ctx.tee_ctx, (void *)fw->data, fw->size);
> +	if (IS_ERR(fw_shm))
> +		return PTR_ERR(fw_shm);
> +
> +	rproc_tee_prepare_args(trproc, TA_RPROC_FW_CMD_LOAD_FW, &arg, param, 1);
> +
> +	/* Provide the address of the firmware image */
> +	param[1] = (struct tee_param) {
> +		.attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT,
> +		.u.memref = {
> +			.shm = fw_shm,
> +			.size = fw->size,
> +			.shm_offs = 0,
> +		},
> +	};
> +
> +	ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> +	if (ret < 0 || arg.ret != 0) {
> +		dev_err(rproc_tee_ctx.dev,
> +			"TA_RPROC_FW_CMD_LOAD_FW invoke failed TEE err: %#x, ret:%d\n",
> +			arg.ret, ret);
> +		if (!ret)
> +			ret = -EIO;

If ret == 0 and arg.ret == <some error>, then this function will print
an error to the log and return success (0). Same with many of the other
functions where you have copy pasted this.

> +	}
> +
> +	tee_shm_free(fw_shm);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_load_fw);
> +
> +static int rproc_tee_get_loaded_rsc_table(struct rproc *rproc, phys_addr_t *rsc_pa,
> +					  size_t *table_sz)
> +{
> +	struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> +	struct rproc_tee *trproc = rproc_to_trproc(rproc);
> +	struct tee_ioctl_invoke_arg arg;
> +	int ret;
> +
> +	if (!rproc_tee_ctx.dev)
> +		return -ENODEV;
> +
> +	if (!trproc)
> +		return -EINVAL;
> +
> +	rproc_tee_prepare_args(trproc, TA_RPROC_FW_CMD_GET_RSC_TABLE, &arg, param, 2);
> +
> +	param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
> +	param[2].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
> +
> +	ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> +	if (ret < 0 || arg.ret != 0) {
> +		dev_err(rproc_tee_ctx.dev,
> +			"TA_RPROC_FW_CMD_GET_RSC_TABLE invoke failed TEE err: %#x, ret:%d\n",
> +			arg.ret, ret);
> +		return -EIO;
> +	}
> +
> +	*table_sz = param[2].u.value.a;

What happened to .b?

> +
> +	if (*table_sz)
> +		*rsc_pa = param[1].u.value.a;

Ditto

> +	else
> +		*rsc_pa  = 0;
> +
> +	return 0;
> +}
> +
> +/**
> + * rproc_tee_parse_fw - Get the resource table from TEE application
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @fw: Pointer to the firmware structure containing the firmware data and size
> + *
> + * This function retrieves the loaded resource table and creates a cached_table copy. Since the
> + * firmware image is signed and potentially encrypted, the firmware must be loaded first to
> + * access the loaded resource table.
> + *
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @fw: Pointer to the firmware structure containing the firmware data and size

Duplicated arguments list...

> + *
> + * Return: 0 on success, or an error code on failure
> + */
> +int rproc_tee_parse_fw(struct rproc *rproc, const struct firmware *fw)
> +{
> +	phys_addr_t rsc_table;
> +	void __iomem *rsc_va;
> +	size_t table_sz;
> +	int ret;
> +
> +	if (!rproc)
> +		return -EINVAL;
> +
> +	/* We need first to Load the firmware, to be able to get the resource table. */
> +	ret = rproc_tee_load_fw(rproc, fw);
> +	if (ret)
> +		return ret;
> +
> +	ret = rproc_tee_get_loaded_rsc_table(rproc, &rsc_table, &table_sz);
> +	if (ret)
> +		goto release_fw;
> +
> +	/*
> +	 * We assume here that the memory mapping is the same between the TEE and Linux kernel
> +	 * contexts. Else a new TEE remoteproc service could be needed to get a copy of the
> +	 * resource table
> +	 */
> +	rsc_va = ioremap_wc(rsc_table, table_sz);

You're using tee_shm for transferring the image, you don't allow Linux
access to any part of the firmware (which is the reason why you need to
load the segments in rproc_parse_fw())...

So just out of curiosity, why is the resource table passed back to Linux
using a ioremap of some random/undefined chunk of memory?

> +	if (!rsc_va) {
> +		dev_err(rproc_tee_ctx.dev, "Unable to map memory region: %pa+%zx\n",
> +			&rsc_table, table_sz);
> +		ret = -ENOMEM;
> +		goto release_fw;
> +	}
> +
> +	/*
> +	 * Create a copy of the resource table to have the same behavior as the ELF loader.
> +	 * This cached table will be used by the remoteproc core after the remoteproc stops
> +	 * to free resources and for crash recovery to reapply the settings.
> +	 * The cached table will be freed by the remoteproc core.
> +	 */
> +	rproc->cached_table = kmemdup((__force void *)rsc_va, table_sz, GFP_KERNEL);

Is rsc_va DDR? And if so, wouldn't memremap() be a more accurate choice
above. If not, why isn't this kzalloc() + memcpy_fromio()?

> +	iounmap(rsc_va);
> +
> +	if (!rproc->cached_table) {
> +		ret = -ENOMEM;
> +		goto release_fw;
> +	}
> +
> +	rproc->table_ptr = rproc->cached_table;
> +	rproc->table_sz = table_sz;
> +
> +	return 0;
> +
> +release_fw:
> +	rproc_tee_release_fw(rproc);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_parse_fw);
> +
> +/**
> + * rproc_tee_find_loaded_rsc_table - Find the loaded resource table loaded by the TEE application
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @fw: Pointer to the firmware structure containing the firmware data and size
> + *
> + * This function retrieves the physical address and size of the resource table loaded by the TEE
> + * application.
> + *
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @fw: Pointer to the firmware structure containing the firmware data and size

More argument duplication.

> + *
> + * Return:  pointer to the resource table if found, or NULL if not found or size is 0
> + */
> +struct resource_table *rproc_tee_find_loaded_rsc_table(struct rproc *rproc,
> +						       const struct firmware *fw)
> +{
> +	phys_addr_t rsc_table;
> +	size_t table_sz;
> +	int ret;
> +
> +	ret = rproc_tee_get_loaded_rsc_table(rproc, &rsc_table, &table_sz);
> +	if (ret)
> +		return NULL;
> +
> +	rproc->table_sz = table_sz;
> +	if (!table_sz)
> +		return NULL;
> +
> +	/*
> +	 * At this step the memory area that contains the resource table should have been registered
> +	 * by the remote proc platform driver and allocated by rproc_alloc_registered_carveouts().
> +	 */
> +	return (struct resource_table *)rproc_pa_to_va(rproc, rsc_table, table_sz, NULL);

rproc_pa_to_va() return type is void *, do you really need this explicit
typecast?

> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_find_loaded_rsc_table);
> +
> +/**
> + * rproc_tee_start - Request the TEE application to start the remote processor
> + *
> + * This function invokes the TA_RPROC_FW_CMD_START command to start the remote processor.
> + *
> + * @rproc: Pointer to the struct rproc representing the remote processor

kernel-doc ordering...

> + *
> + * Return: Returns 0 on success, -EINVAL or -EIO on failure
> + */
> +int rproc_tee_start(struct rproc *rproc)
> +{
> +	struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> +	struct rproc_tee *trproc = rproc_to_trproc(rproc);
> +	struct tee_ioctl_invoke_arg arg;
> +	int ret = 0;

First access of ret is an assignment, no need to zero-initialize it
here.

> +
> +	if (!trproc)
> +		return -EINVAL;

There's an inconsistency in that rproc_tee_ctx.dev is used without first
checking that it's valid in this function...

> +
> +	rproc_tee_prepare_args(trproc, TA_RPROC_FW_CMD_START, &arg, param, 0);
> +
> +	ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> +	if (ret < 0 || arg.ret != 0) {
> +		dev_err(rproc_tee_ctx.dev,
> +			"TA_RPROC_FW_CMD_START invoke failed TEE err: %#x, ret:%d\n", arg.ret, ret);
> +		if (!ret)
> +			return  -EIO;

Why not assigning ret and falling through, like in most other functions?

> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_start);
> +
> +/**
> + * rproc_tee_stop - Request the TEE application to start the remote processor
> + *
> + * This function invokes the TA_RPROC_FW_CMD_STOP command to stop the remote processor.
> + *
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + *
> + * Return: Returns 0 on success, -EINVAL or -EIO on failure
> + */
> +int rproc_tee_stop(struct rproc *rproc)
> +{
> +	struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> +	struct rproc_tee *trproc = rproc_to_trproc(rproc);
> +	struct tee_ioctl_invoke_arg arg;
> +	int ret;
> +
> +	if (!trproc)
> +		return -EINVAL;
> +
> +	rproc_tee_prepare_args(trproc, TA_RPROC_FW_CMD_STOP, &arg, param, 0);
> +
> +	ret = tee_client_invoke_func(rproc_tee_ctx.tee_ctx, &arg, param);
> +	if (ret < 0 || arg.ret != 0) {
> +		dev_err(rproc_tee_ctx.dev,
> +			"TA_RPROC_FW_CMD_STOP invoke failed TEE err: %#x, ret:%d\n", arg.ret, ret);
> +		if (!ret)
> +			ret = -EIO;
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_stop);
> +
> +static const struct tee_client_device_id rproc_tee_id_table[] = {
> +	{UUID_INIT(0x80a4c275, 0x0a47, 0x4905, 0x82, 0x85, 0x14, 0x86, 0xa9, 0x77, 0x1a, 0x08)},
> +	{}
> +};
> +
> +/**
> + * rproc_tee_register - Register a remote processor controlled by a TEE application.
> + *
> + * This function registers a remote processor that will be managed by a TEE application,by opening
> + * a session with the TEE client.
> + *
> + * @dev: Pointer to client rproc device
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + * @rproc_id: ID of the remote processor
> + *
> + * Return: Returns 0 on success, or an error code on failure
> + */
> +int rproc_tee_register(struct device *dev, struct rproc *rproc, unsigned int rproc_id)
> +{
> +	struct tee_param param[MAX_TEE_PARAM_ARRAY_MEMBER];
> +	struct tee_ioctl_open_session_arg sess_arg;
> +	struct tee_client_device *tee_device;
> +	struct rproc_tee *trproc;
> +	struct device_link *link;
> +	int ret;
> +
> +	spin_lock(&ctx_lock);

Why is this a spin_lock?

To my understanding the purpose of ctx_lock is to ensure mutual
exclusion of access to rproc_tee_ctx, but this doesn't look like it's
done from a context that isn't able to tolerate a mutex.

In particular during boot, if you have multiple remoteprocs being
registred, you're going to waste precious CPU cycles just spinning here.


And if it is a spinlock because you might enter here from some interrupt
context, how do you ensure this won't deadlock?

> +	/*
> +	 * Test if the device has been probed by the TEE bus. In case of failure, we ignore the
> +	 * reason. The bus could be not yet probed or the service not available in the secure
> +	 * firmware.The assumption in such a case is that the TEE remoteproc is not probed.
> +	 */
> +	if (!rproc_tee_ctx.dev) {
> +		ret = -EPROBE_DEFER;
> +		goto out;
> +	}
> +
> +	trproc = kzalloc(sizeof(*trproc), GFP_KERNEL);
> +	if (!trproc) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	tee_device = to_tee_client_device(rproc_tee_ctx.dev);
> +	memset(&sess_arg, 0, sizeof(sess_arg));
> +
> +	memcpy(sess_arg.uuid, tee_device->id.uuid.b, TEE_IOCTL_UUID_LEN);
> +
> +	sess_arg.clnt_login = TEE_IOCTL_LOGIN_REE_KERNEL;
> +	sess_arg.num_params = 1;
> +
> +	param[0] = (struct tee_param) {
> +		.attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INPUT,
> +		.u.value.a = rproc_id,
> +	};

I'm not familiar with the details of the tee calling convention, but do
you really need 4 entries in the param array and if so, would it make
sense to zero-initialize the other elements - like you do in all other
functions?

> +
> +	ret = tee_client_open_session(rproc_tee_ctx.tee_ctx, &sess_arg, param);
> +	if (ret < 0 || sess_arg.ret != 0) {
> +		dev_err(dev, "tee_client_open_session failed, err: %#x\n", sess_arg.ret);
> +		ret = -EINVAL;
> +		goto free_tproc;
> +	}
> +
> +	trproc->rproc_id = rproc_id;
> +	trproc->session_id = sess_arg.session;
> +
> +	trproc->rproc = rproc;
> +
> +	/* Create device link between the rproc device and the TEE device */

This comment would be more useful if it documented why the link is
created - the fact that a link is added between the two devices can be
read on the next line...

> +	link = device_link_add(dev, rproc_tee_ctx.dev, DL_FLAG_AUTOREMOVE_CONSUMER);
> +	if (!link) {
> +		ret = -ENOMEM;
> +		goto close_tee;
> +	}
> +	list_add_tail(&trproc->node, &rproc_tee_ctx.sessions);
> +
> +	goto out;

Please don't use goto to skip over the error handling. ret is going to
be 0 here, so unlock and return 0 here to make it clear that this is the
point of successful return.

> +
> +close_tee:
> +	if (tee_client_close_session(rproc_tee_ctx.tee_ctx, trproc->session_id))
> +		dev_err(rproc_tee_ctx.dev, "tee_client_close_session failed\n");
> +free_tproc:
> +	kfree(trproc);
> +out:
> +	spin_unlock(&ctx_lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_register);
> +
> +/**
> + * rproc_tee_unregister - Register a remote processor controlled by a TEE application.
> + *
> + * This function unregisters a remote processor previously registered by the rproc_tee_register()
> + * function.
> + *
> + * @dev: Pointer to client rproc device
> + * @rproc: Pointer to the struct rproc representing the remote processor
> + *
> + * Return: Returns 0 on success, or an error code on failure
> + */
> +int rproc_tee_unregister(struct device *dev, struct rproc *rproc)
> +{
> +	struct rproc_tee *trproc = rproc_to_trproc(rproc);
> +	int ret;
> +
> +	if (!trproc)
> +		return -EINVAL;
> +
> +	spin_lock(&ctx_lock);

This lock is taken after you have traversed the rproc_tee_ctx.session
list in a racy fashion.

> +
> +	ret = tee_client_close_session(rproc_tee_ctx.tee_ctx, trproc->session_id);
> +	if (ret < 0)
> +		dev_err(rproc_tee_ctx.dev, "tee_client_close_session failed, err: %#x\n", ret);
> +
> +	spin_unlock(&ctx_lock);
> +
> +	list_del(&trproc->node);

Although, I might misunderstand your locking scheme, because here you're
modifying the sessions list immediately after leaving the mutual
exclusion region?

> +	kfree(trproc);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(rproc_tee_unregister);
> +
> +static int rproc_tee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
> +{
> +	/* Today we support only the OP-TEE, could be extend to other tees */
> +	return (ver->impl_id == TEE_IMPL_ID_OPTEE);
> +}
> +
> +static int rproc_tee_probe(struct device *dev)
> +{
> +	struct tee_context *tee_ctx;
> +
> +	/* Open context with TEE driver */
> +	tee_ctx = tee_client_open_context(NULL, rproc_tee_ctx_match, NULL, NULL);
> +	if (IS_ERR(tee_ctx))
> +		return PTR_ERR(tee_ctx);
> +
> +	spin_lock(&ctx_lock);
> +	rproc_tee_ctx.dev = dev;
> +	rproc_tee_ctx.tee_ctx = tee_ctx;
> +	INIT_LIST_HEAD(&rproc_tee_ctx.sessions);
> +	spin_unlock(&ctx_lock);
> +
> +	return 0;
> +}
> +
> +static int rproc_tee_remove(struct device *dev)
> +{
> +	spin_lock(&ctx_lock);
> +	tee_client_close_context(rproc_tee_ctx.tee_ctx);
> +	rproc_tee_ctx.dev = NULL;
> +	rproc_tee_ctx.tee_ctx = NULL;
> +	spin_unlock(&ctx_lock);
> +
> +	return 0;
> +}
> +
> +MODULE_DEVICE_TABLE(tee, rproc_tee_id_table);
> +
> +static struct tee_client_driver rproc_tee_fw_driver = {
> +	.id_table	= rproc_tee_id_table,
> +	.driver		= {
> +		.name		= KBUILD_MODNAME,
> +		.bus		= &tee_bus_type,
> +		.probe		= rproc_tee_probe,
> +		.remove		= rproc_tee_remove,
> +	},
> +};
> +
> +static int __init rproc_tee_fw_mod_init(void)
> +{
> +	return driver_register(&rproc_tee_fw_driver.driver);
> +}
> +
> +static void __exit rproc_tee_fw_mod_exit(void)
> +{
> +	driver_unregister(&rproc_tee_fw_driver.driver);
> +}
> +
> +module_init(rproc_tee_fw_mod_init);
> +module_exit(rproc_tee_fw_mod_exit);
> +
> +MODULE_DESCRIPTION(" remote processor TEE module");

Why is there a space in the start of the description?

> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/remoteproc_tee.h b/include/linux/remoteproc_tee.h
> new file mode 100644
> index 000000000000..659bd77a4f12
> --- /dev/null
> +++ b/include/linux/remoteproc_tee.h
> @@ -0,0 +1,90 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright(c) 2024 STMicroelectronics

Year?

> + */
> +
> +#ifndef REMOTEPROC_TEE_H
> +#define REMOTEPROC_TEE_H
> +
> +#include <linux/tee_drv.h>
> +#include <linux/firmware.h>
> +#include <linux/remoteproc.h>
> +
> +struct rproc;
> +struct rproc_tee;

rproc_tee is not used in the API, so there shouldn't be a need for
forward declaring it.

struct rproc is defined in linux/remoteproc.h, so that should be fine to
omit as well.

> +
> +#if IS_ENABLED(CONFIG_REMOTEPROC_TEE)
> +
> +int rproc_tee_register(struct device *dev, struct rproc *rproc, unsigned int rproc_id);
> +int rproc_tee_unregister(struct device *dev, struct rproc *rproc);
> +int rproc_tee_parse_fw(struct rproc *rproc, const struct firmware *fw);
> +int rproc_tee_load_fw(struct rproc *rproc, const struct firmware *fw);
> +void rproc_tee_release_fw(struct rproc *rproc);
> +struct resource_table *rproc_tee_find_loaded_rsc_table(struct rproc *rproc,
> +						       const struct firmware *fw);
> +int rproc_tee_start(struct rproc *rproc);
> +int rproc_tee_stop(struct rproc *rproc);
> +
> +#else
> +
> +static inline int rproc_tee_register(struct device *dev, struct rproc *rproc, unsigned int rproc_id)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int rproc_tee_parse_fw(struct rproc *rproc, const struct firmware *fw)
> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +
> +	return 0;
> +}
> +
> +static inline int rproc_tee_unregister(struct device *dev, struct rproc *rproc)
> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +
> +	return 0;
> +}
> +
> +static inline int rproc_tee_load_fw(struct rproc *rproc,  const struct firmware *fw)

Double space after the ','

Regards,
Bjorn

> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +
> +	return 0;
> +}
> +
> +static inline int rproc_tee_start(struct rproc *rproc)
> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +
> +	return 0;
> +}
> +
> +static inline int rproc_tee_stop(struct rproc *rproc)
> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +
> +	return 0;
> +}
> +
> +static inline void rproc_tee_release_fw(struct rproc *rproc)
> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +}
> +
> +static inline struct resource_table *
> +rproc_tee_find_loaded_rsc_table(struct rproc *rproc, const struct firmware *fw)
> +{
> +	/* This shouldn't be possible */
> +	WARN_ON(1);
> +
> +	return NULL;
> +}
> +#endif /* CONFIG_REMOTEPROC_TEE */
> +#endif /* REMOTEPROC_TEE_H */
> -- 
> 2.25.1
> 

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