Re: [PATCH v8 2/5] remoteproc: Add TEE support

Arnaud POULIQUEN
2024-07-04T08:07:00Z

On 7/3/24 17:14, Mathieu Poirier wrote:
> On Wed, Jul 03, 2024 at 09:19:44AM +0200, Arnaud POULIQUEN wrote:
>> Hello Mathieu
>>
>> On 7/2/24 18:44, Mathieu Poirier wrote:
>>> Good morning,
>>>
>>> On Fri, Jun 21, 2024 at 04:37:56PM +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 secure part this driver offers a client
>>>> interface to load a firmware by the secure part.
>>>> This firmware could be authenticated by the secure trusted application.
>>>>
>>>> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
>>>> ---
>>>> Updates vs previous version:
>>>> - rename tee_remoteproc.* file to rmeoteproc_tee.*,
>>>> - rename TEE_REMOTEPROC config to REMOTEPROC_TEE,
>>>> - remove "stm32" in some variable declarations,
>>>> - remove useless "remoteproc_internal.h" include,
>>>> - fix tee_rproc_ctx devm_kzalloc.
>>>> - rework module description
>>>> ---
>>>> drivers/remoteproc/Kconfig | 10 +
>>>> drivers/remoteproc/Makefile | 1 +
>>>> drivers/remoteproc/remoteproc_tee.c | 446 ++++++++++++++++++++++++++++
>>>> include/linux/remoteproc.h | 4 +
>>>> include/linux/remoteproc_tee.h | 100 +++++++
>>>> 5 files changed, 561 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 48845dc8fa85..278f197acb90 100644
>>>> --- a/drivers/remoteproc/Kconfig
>>>> +++ b/drivers/remoteproc/Kconfig
>>>> @@ -365,6 +365,16 @@ config XLNX_R5_REMOTEPROC
>>>>
>>>> It's safe to say N if not interested in using RPU r5f cores.
>>>>
>>>> +
>>>> +config REMOTEPROC_TEE
>>>> + tristate "Remoteproc support by a TEE application"
>>>> + depends on OPTEE
>>>> + help
>>>> + Support a remote processor with a TEE application. The Trusted
>>>> + Execution Context is responsible for loading the trusted firmware
>>>> + image and managing the remote processor's lifecycle.
>>>> + This can be either built-in or a loadable module.
>>>> +
>>>> endif # REMOTEPROC
>>>>
>>>> endmenu
>>>> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
>>>> index 91314a9b43ce..b4eb37177005 100644
>>>> --- a/drivers/remoteproc/Makefile
>>>> +++ b/drivers/remoteproc/Makefile
>>>> @@ -36,6 +36,7 @@ obj-$(CONFIG_RCAR_REMOTEPROC) += rcar_rproc.o
>>>> obj-$(CONFIG_ST_REMOTEPROC) += st_remoteproc.o
>>>> obj-$(CONFIG_ST_SLIM_REMOTEPROC) += st_slim_rproc.o
>>>> obj-$(CONFIG_STM32_RPROC) += stm32_rproc.o
>>>> +obj-$(CONFIG_REMOTEPROC_TEE) += remoteproc_tee.o
>>>> obj-$(CONFIG_TI_K3_DSP_REMOTEPROC) += ti_k3_dsp_remoteproc.o
>>>> obj-$(CONFIG_TI_K3_R5_REMOTEPROC) += ti_k3_r5_remoteproc.o
>>>> obj-$(CONFIG_XLNX_R5_REMOTEPROC) += xlnx_r5_remoteproc.o
>>>> diff --git a/drivers/remoteproc/remoteproc_tee.c b/drivers/remoteproc/remoteproc_tee.c
>>>> new file mode 100644
>>>> index 000000000000..70cb67451767
>>>> --- /dev/null
>>>> +++ b/drivers/remoteproc/remoteproc_tee.c
>>>> @@ -0,0 +1,446 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-or-later
>>>> +/*
>>>> + * Copyright (C) STMicroelectronics 2024
>>>> + * Author: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
>>>> + */
>>>> +
>>>> +#include <linux/firmware.h>
>>>> +#include <linux/io.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/remoteproc.h>
>>>> +#include <linux/remoteproc_tee.h>
>>>> +#include <linux/slab.h>
>>>> +#include <linux/tee_drv.h>
>>>> +
>>>> +#define MAX_TEE_PARAM_ARRY_MEMBER 4
>>>> +
>>>> +/*
>>>> + * Authentication of the firmware and load in the remote processor memory
>>>> + *
>>>> + * [in] params[0].value.a: unique 32bit identifier of the remote processor
>>>> + * [in] params[1].memref: buffer containing the image of the buffer
>>>> + */
>>>> +#define TA_RPROC_FW_CMD_LOAD_FW 1
>>>> +
>>>> +/*
>>>> + * Start the remote processor
>>>> + *
>>>> + * [in] params[0].value.a: unique 32bit identifier of the remote processor
>>>> + */
>>>> +#define TA_RPROC_FW_CMD_START_FW 2
>>>> +
>>>> +/*
>>>> + * Stop the remote processor
>>>> + *
>>>> + * [in] params[0].value.a: unique 32bit identifier of the remote processor
>>>> + */
>>>> +#define TA_RPROC_FW_CMD_STOP_FW 3
>>>> +
>>>> +/*
>>>> + * Return the address of the resource table, or 0 if not found
>>>> + * No check is done to verify that the address returned is accessible by
>>>> + * the non secure context. If the resource table is loaded in a protected
>>>> + * memory the access by the non secure context will lead to a data abort.
>>>> + *
>>>> + * [in] params[0].value.a: unique 32bit identifier of the remote processor
>>>> + * [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
>>>> +
>>>> +/*
>>>> + * Return the address of the core dump
>>>> + *
>>>> + * [in] params[0].value.a: unique 32bit identifier of the remote processor
>>>> + * [out] params[1].memref: address of the core dump image if exist,
>>>> + * else return Null
>>>> + */
>>>> +#define TA_RPROC_FW_CMD_GET_COREDUMP 5
>>>> +
>>>> +struct tee_rproc_context {
>>>> + struct list_head sessions;
>>>> + struct tee_context *tee_ctx;
>>>> + struct device *dev;
>>>> +};
>>>> +
>>>> +static struct tee_rproc_context *tee_rproc_ctx;
>>>> +
>>>> +static void tee_rproc_prepare_args(struct tee_rproc *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_ARRY_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,
>>>> + };
>>>> +}
>>>> +
>>>> +int tee_rproc_load_fw(struct rproc *rproc, const struct firmware *fw)
>>>> +{
>>>> + struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
>>>> + struct tee_rproc *trproc = rproc->tee_interface;
>>>> + struct tee_ioctl_invoke_arg arg;
>>>> + struct tee_shm *fw_shm;
>>>> + int ret;
>>>> +
>>>> + if (!trproc)
>>>> + return -EINVAL;
>>>> +
>>>> + fw_shm = tee_shm_register_kernel_buf(tee_rproc_ctx->tee_ctx, (void *)fw->data, fw->size);
>>>> + if (IS_ERR(fw_shm))
>>>> + return PTR_ERR(fw_shm);
>>>> +
>>>> + tee_rproc_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(tee_rproc_ctx->tee_ctx, &arg, param);
>>>> + if (ret < 0 || arg.ret != 0) {
>>>> + dev_err(tee_rproc_ctx->dev,
>>>> + "TA_RPROC_FW_CMD_LOAD_FW invoke failed TEE err: %x, ret:%x\n",
>>>> + arg.ret, ret);
>>>> + if (!ret)
>>>> + ret = -EIO;
>>>> + }
>>>> +
>>>> + tee_shm_free(fw_shm);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(tee_rproc_load_fw);
>>>> +
>>>> +static int tee_rproc_get_loaded_rsc_table(struct rproc *rproc, phys_addr_t *rsc_pa,
>>>> + size_t *table_sz)
>>>> +{
>>>> + struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
>>>> + struct tee_rproc *trproc = rproc->tee_interface;
>>>> + struct tee_ioctl_invoke_arg arg;
>>>> + int ret;
>>>> +
>>>> + tee_rproc_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(tee_rproc_ctx->tee_ctx, &arg, param);
>>>> + if (ret < 0 || arg.ret != 0) {
>>>> + dev_err(tee_rproc_ctx->dev,
>>>> + "TA_RPROC_FW_CMD_GET_RSC_TABLE invoke failed TEE err: %x, ret:%x\n",
>>>> + arg.ret, ret);
>>>> + return -EIO;
>>>> + }
>>>> +
>>>> + *table_sz = param[2].u.value.a;
>>>> +
>>>> + if (*table_sz)
>>>> + *rsc_pa = param[1].u.value.a;
>>>> + else
>>>> + *rsc_pa = 0;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +int tee_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
>>>> +{
>>>> + phys_addr_t rsc_table;
>>>> + void __iomem *rsc_va;
>>>> + size_t table_sz;
>>>> + int ret;
>>>> +
>>>> + ret = tee_rproc_load_fw(rproc, fw);
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + ret = tee_rproc_get_loaded_rsc_table(rproc, &rsc_table, &table_sz);
>>>> + if (ret)
>>>> + return ret;
>>>
>>> Do we need an API to unload the firware from memory too? If anything fails we
>>> still have firmware loaded into memory.
>>
>> For the time being, the clean-up of the memory is not implemented in OP-TEE.
>
> In my opinion cleaning up the firmware image loaded to memory when something
> fails is important and should be part of this patchset. Looking at the error
> path in this function, it is clear something is missing.

Please, could you detail what risks you see in not implementing the memory
clean-up at this first step?

Currently, OP-TEE upstream does not clean the memory. Upon the next load, it
will either be overwritten or left unused by the newly authenticated firmware.

If your concern is about the ability to read the code, the code is already
accessible in the binary firmware image on the Linux filesystem.

As a next step a platform-dependent strategy has to be implemented to enhance
firmware protection:
- Ensure the integrity of the code.
- Preserve secrets.

However, OP-TEE cannot trust the Non-secure context for this. Expecting Linux to
call a clean-up service does not seem reliable to me.

In the downstream stm32mp platform, we have implemented the clean-up but above
all, ensured that Linux never has access to the remote processor firmware code
and data by using firewall configurations.
For time being we print a warning message on OP-TEE upstream[1]

[1]https://elixir.bootlin.com/op-tee/latest/source/core/drivers/remoteproc/stm32_remoteproc.c#L361

Thanks,
Arnaud

>
>> I plan to upstream this part in a second step, associated with a memory protection
>> strategy. This should be directly implemented in the OP-TEE service to avoid
>> reliance on Linux error management.
>> Nonetheless, an API could be added to clean the memory if needed.
>>
>> Thanks,
>> Arnaud
>>
>>>
>>> More comments to come later.
>>>
>>> Mathieu
>>>
>>>> +
>>>> + /*
>>>> + * 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);
>>>> + if (IS_ERR_OR_NULL(rsc_va)) {
>>>> + dev_err(tee_rproc_ctx->dev, "Unable to map memory region: %pa+%zx\n",
>>>> + &rsc_table, table_sz);
>>>> + return -ENOMEM;
>>>> + }
>>>> +
>>>> + /*
>>>> + * Create a copy of the resource table to have the same behavior as the elf loader.
>>>> + * This cached table will be used after the remoteproc stops to free resources, and for
>>>> + * crash recovery to reapply the settings.
>>>> + */
>>>> + rproc->cached_table = kmemdup((__force void *)rsc_va, table_sz, GFP_KERNEL);
>>>> + if (!rproc->cached_table) {
>>>> + ret = -ENOMEM;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + rproc->table_ptr = rproc->cached_table;
>>>> + rproc->table_sz = table_sz;
>>>> +
>>>> +out:
>>>> + iounmap(rsc_va);
>>>> + return ret;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(tee_rproc_parse_fw);
>>>> +
>>>> +struct resource_table *tee_rproc_find_loaded_rsc_table(struct rproc *rproc,
>>>> + const struct firmware *fw)
>>>> +{
>>>> + struct tee_rproc *trproc = rproc->tee_interface;
>>>> + phys_addr_t rsc_table;
>>>> + size_t table_sz;
>>>> + int ret;
>>>> +
>>>> + if (!trproc)
>>>> + return ERR_PTR(-EINVAL);
>>>> +
>>>> + ret = tee_rproc_get_loaded_rsc_table(rproc, &rsc_table, &table_sz);
>>>> + if (ret)
>>>> + return ERR_PTR(ret);
>>>> +
>>>> + rproc->table_sz = table_sz;
>>>> + if (!table_sz)
>>>> + return NULL;
>>>> +
>>>> + /*
>>>> + * At this step the memory area that contains the resource table should have be declared
>>>> + * in 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);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(tee_rproc_find_loaded_rsc_table);
>>>> +
>>>> +int tee_rproc_start(struct rproc *rproc)
>>>> +{
>>>> + struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
>>>> + struct tee_rproc *trproc = rproc->tee_interface;
>>>> + struct tee_ioctl_invoke_arg arg;
>>>> + int ret = 0;
>>>> +
>>>> + if (!trproc)
>>>> + return -EINVAL;
>>>> +
>>>> + tee_rproc_prepare_args(trproc, TA_RPROC_FW_CMD_START_FW, &arg, param, 0);
>>>> +
>>>> + ret = tee_client_invoke_func(tee_rproc_ctx->tee_ctx, &arg, param);
>>>> + if (ret < 0 || arg.ret != 0) {
>>>> + dev_err(tee_rproc_ctx->dev,
>>>> + "TA_RPROC_FW_CMD_START_FW invoke failed TEE err: %x, ret:%x\n",
>>>> + arg.ret, ret);
>>>> + if (!ret)
>>>> + return -EIO;
>>>> + }
>>>> +
>>>> + return 0;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(tee_rproc_start);
>>>> +
>>>> +int tee_rproc_stop(struct rproc *rproc)
>>>> +{
>>>> + struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
>>>> + struct tee_rproc *trproc = rproc->tee_interface;
>>>> + struct tee_ioctl_invoke_arg arg;
>>>> + int ret;
>>>> +
>>>> + if (!trproc)
>>>> + return -EINVAL;
>>>> +
>>>> + tee_rproc_prepare_args(trproc, TA_RPROC_FW_CMD_STOP_FW, &arg, param, 0);
>>>> +
>>>> + ret = tee_client_invoke_func(tee_rproc_ctx->tee_ctx, &arg, param);
>>>> + if (ret < 0 || arg.ret != 0) {
>>>> + dev_err(tee_rproc_ctx->dev,
>>>> + "TA_RPROC_FW_CMD_STOP_FW invoke failed TEE err: %x, ret:%x\n",
>>>> + arg.ret, ret);
>>>> + if (!ret)
>>>> + ret = -EIO;
>>>> + }
>>>> +
>>>> + return ret;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(tee_rproc_stop);
>>>> +
>>>> +static const struct tee_client_device_id tee_rproc_id_table[] = {
>>>> + {UUID_INIT(0x80a4c275, 0x0a47, 0x4905, 0x82, 0x85, 0x14, 0x86, 0xa9, 0x77, 0x1a, 0x08)},
>>>> + {}
>>>> +};
>>>> +
>>>> +struct tee_rproc *tee_rproc_register(struct device *dev, struct rproc *rproc, unsigned int rproc_id)
>>>> +{
>>>> + struct tee_param param[MAX_TEE_PARAM_ARRY_MEMBER];
>>>> + struct tee_ioctl_open_session_arg sess_arg;
>>>> + struct tee_client_device *tee_device;
>>>> + struct tee_rproc *trproc, *p_err;
>>>> + int ret;
>>>> +
>>>> + /*
>>>> + * 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 (!tee_rproc_ctx)
>>>> + return ERR_PTR(-EPROBE_DEFER);
>>>> +
>>>> + /* Prevent tee rproc module from being removed */
>>>> + if (!try_module_get(THIS_MODULE)) {
>>>> + dev_err(tee_rproc_ctx->dev, "can't get owner\n");
>>>> + return ERR_PTR(-ENODEV);
>>>> + }
>>>> +
>>>> + trproc = devm_kzalloc(dev, sizeof(*trproc), GFP_KERNEL);
>>>> + if (!trproc) {
>>>> + p_err = ERR_PTR(-ENOMEM);
>>>> + goto module_put;
>>>> + }
>>>> + tee_device = to_tee_client_device(tee_rproc_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,
>>>> + };
>>>> +
>>>> + ret = tee_client_open_session(tee_rproc_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);
>>>> + p_err = ERR_PTR(-EINVAL);
>>>> + goto module_put;
>>>> + }
>>>> +
>>>> + trproc->parent = dev;
>>>> + trproc->rproc_id = rproc_id;
>>>> + trproc->session_id = sess_arg.session;
>>>> +
>>>> + trproc->rproc = rproc;
>>>> + rproc->tee_interface = trproc;
>>>> +
>>>> + list_add_tail(&trproc->node, &tee_rproc_ctx->sessions);
>>>> +
>>>> + return trproc;
>>>> +
>>>> +module_put:
>>>> + module_put(THIS_MODULE);
>>>> + return p_err;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(tee_rproc_register);
>>>> +
>>>> +int tee_rproc_unregister(struct tee_rproc *trproc)
>>>> +{
>>>> + struct rproc *rproc = trproc->rproc;
>>>> + int ret;
>>>> +
>>>> + ret = tee_client_close_session(tee_rproc_ctx->tee_ctx, trproc->session_id);
>>>> + if (ret < 0)
>>>> + dev_err(trproc->parent, "tee_client_close_session failed, err: %x\n", ret);
>>>> +
>>>> + list_del(&trproc->node);
>>>> + rproc->tee_interface = NULL;
>>>> +
>>>> + module_put(THIS_MODULE);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(tee_rproc_unregister);
>>>> +
>>>> +static int tee_rproc_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 tee_rproc_probe(struct device *dev)
>>>> +{
>>>> + struct tee_context *tee_ctx;
>>>> + int ret;
>>>> +
>>>> + /* Open context with TEE driver */
>>>> + tee_ctx = tee_client_open_context(NULL, tee_rproc_ctx_match, NULL, NULL);
>>>> + if (IS_ERR(tee_ctx))
>>>> + return PTR_ERR(tee_ctx);
>>>> +
>>>> + tee_rproc_ctx = devm_kzalloc(dev, sizeof(*tee_rproc_ctx), GFP_KERNEL);
>>>> + if (!tee_rproc_ctx) {
>>>> + ret = -ENOMEM;
>>>> + goto err;
>>>> + }
>>>> +
>>>> + tee_rproc_ctx->dev = dev;
>>>> + tee_rproc_ctx->tee_ctx = tee_ctx;
>>>> + INIT_LIST_HEAD(&tee_rproc_ctx->sessions);
>>>> +
>>>> + return 0;
>>>> +err:
>>>> + tee_client_close_context(tee_ctx);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int tee_rproc_remove(struct device *dev)
>>>> +{
>>>> + struct tee_rproc *entry, *tmp;
>>>> +
>>>> + list_for_each_entry_safe(entry, tmp, &tee_rproc_ctx->sessions, node) {
>>>> + tee_client_close_session(tee_rproc_ctx->tee_ctx, entry->session_id);
>>>> + list_del(&entry->node);
>>>> + kfree(entry);
>>>> + }
>>>> +
>>>> + tee_client_close_context(tee_rproc_ctx->tee_ctx);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +MODULE_DEVICE_TABLE(tee, tee_rproc_id_table);
>>>> +
>>>> +static struct tee_client_driver tee_rproc_fw_driver = {
>>>> + .id_table = tee_rproc_id_table,
>>>> + .driver = {
>>>> + .name = KBUILD_MODNAME,
>>>> + .bus = &tee_bus_type,
>>>> + .probe = tee_rproc_probe,
>>>> + .remove = tee_rproc_remove,
>>>> + },
>>>> +};
>>>> +
>>>> +static int __init tee_rproc_fw_mod_init(void)
>>>> +{
>>>> + return driver_register(&tee_rproc_fw_driver.driver);
>>>> +}
>>>> +
>>>> +static void __exit tee_rproc_fw_mod_exit(void)
>>>> +{
>>>> + driver_unregister(&tee_rproc_fw_driver.driver);
>>>> +}
>>>> +
>>>> +module_init(tee_rproc_fw_mod_init);
>>>> +module_exit(tee_rproc_fw_mod_exit);
>>>> +
>>>> +MODULE_DESCRIPTION(" remote processor support with a TEE application");
>>>> +MODULE_LICENSE("GPL");
>>>> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
>>>> index 8fd0d7f63c8e..fbe1d6793709 100644
>>>> --- a/include/linux/remoteproc.h
>>>> +++ b/include/linux/remoteproc.h
>>>> @@ -503,6 +503,8 @@ enum rproc_features {
>>>> RPROC_MAX_FEATURES,
>>>> };
>>>>
>>>> +struct tee_rproc;
>>>> +
>>>> /**
>>>> * struct rproc - represents a physical remote processor device
>>>> * @node: list node of this rproc object
>>>> @@ -545,6 +547,7 @@ enum rproc_features {
>>>> * @cdev: character device of the rproc
>>>> * @cdev_put_on_release: flag to indicate if remoteproc should be shutdown on @char_dev release
>>>> * @features: indicate remoteproc features
>>>> + * @tee_interface: pointer to the remoteproc tee context
>>>> */
>>>> struct rproc {
>>>> struct list_head node;
>>>> @@ -586,6 +589,7 @@ struct rproc {
>>>> struct cdev cdev;
>>>> bool cdev_put_on_release;
>>>> DECLARE_BITMAP(features, RPROC_MAX_FEATURES);
>>>> + struct tee_rproc *tee_interface;
>>>> };
>>>>
>>>> /**
>>>> diff --git a/include/linux/remoteproc_tee.h b/include/linux/remoteproc_tee.h
>>>> new file mode 100644
>>>> index 000000000000..ccf34a218d54
>>>> --- /dev/null
>>>> +++ b/include/linux/remoteproc_tee.h
>>>> @@ -0,0 +1,100 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
>>>> +/*
>>>> + * Copyright(c) 2024 STMicroelectronics
>>>> + */
>>>> +
>>>> +#ifndef REMOTEPROC_TEE_H
>>>> +#define REMOTEPROC_TEE_H
>>>> +
>>>> +#include <linux/tee_drv.h>
>>>> +#include <linux/firmware.h>
>>>> +#include <linux/remoteproc.h>
>>>> +
>>>> +struct rproc;
>>>> +
>>>> +/**
>>>> + * struct tee_rproc - TEE remoteproc structure
>>>> + * @node: Reference in list
>>>> + * @rproc: Remoteproc reference
>>>> + * @parent: Parent device
>>>> + * @rproc_id: Identifier of the target firmware
>>>> + * @session_id: TEE session identifier
>>>> + */
>>>> +struct tee_rproc {
>>>> + struct list_head node;
>>>> + struct rproc *rproc;
>>>> + struct device *parent;
>>>> + u32 rproc_id;
>>>> + u32 session_id;
>>>> +};
>>>> +
>>>> +#if IS_REACHABLE(CONFIG_REMOTEPROC_TEE)
>>>> +
>>>> +struct tee_rproc *tee_rproc_register(struct device *dev, struct rproc *rproc,
>>>> + unsigned int rproc_id);
>>>> +int tee_rproc_unregister(struct tee_rproc *trproc);
>>>> +int tee_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw);
>>>> +int tee_rproc_load_fw(struct rproc *rproc, const struct firmware *fw);
>>>> +struct resource_table *tee_rproc_find_loaded_rsc_table(struct rproc *rproc,
>>>> + const struct firmware *fw);
>>>> +int tee_rproc_start(struct rproc *rproc);
>>>> +int tee_rproc_stop(struct rproc *rproc);
>>>> +
>>>> +#else
>>>> +
>>>> +static inline struct tee_rproc *tee_rproc_register(struct device *dev, struct rproc *rproc,
>>>> + unsigned int rproc_id)
>>>> +{
>>>> + return ERR_PTR(-ENODEV);
>>>> +}
>>>> +
>>>> +static int tee_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
>>>> +{
>>>> + /* This shouldn't be possible */
>>>> + WARN_ON(1);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static inline int tee_rproc_unregister(struct tee_rproc *trproc)
>>>> +{
>>>> + /* This shouldn't be possible */
>>>> + WARN_ON(1);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static inline int tee_rproc_load_fw(struct rproc *rproc, const struct firmware *fw)
>>>> +{
>>>> + /* This shouldn't be possible */
>>>> + WARN_ON(1);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static inline int tee_rproc_start(struct rproc *rproc)
>>>> +{
>>>> + /* This shouldn't be possible */
>>>> + WARN_ON(1);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static inline int tee_rproc_stop(struct rproc *rproc)
>>>> +{
>>>> + /* This shouldn't be possible */
>>>> + WARN_ON(1);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static inline struct resource_table *
>>>> +tee_rproc_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
>>>>