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From: Balint Dobszay <balint.dobszay@arm.com>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: op-tee@lists.trustedfirmware.org, linux-doc@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
 jens.wiklander@linaro.org, corbet@lwn.net, sudeep.holla@arm.com,
 rdunlap@infradead.org, krzk@kernel.org, gyorgy.szing@arm.com
Subject: Re: [PATCH v2 2/3] tee: tstee: Add Trusted Services TEE driver
Date: Mon, 04 Mar 2024 10:04:51 +0100
Message-ID: <666ACEA9-7A19-46BC-BC85-837021910900@arm.com>
In-Reply-To: <CAFA6WYOKtxGTU33BY_z1H01UF41rm6g-LTxUi-DX4CJrV-aT3w@mail.gmail.com>
References: <20240223095133.109046-1-balint.dobszay@arm.com>
 <20240223095133.109046-3-balint.dobszay@arm.com>
 <CAFA6WYOKtxGTU33BY_z1H01UF41rm6g-LTxUi-DX4CJrV-aT3w@mail.gmail.com>
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On 27 Feb 2024, at 8:08, Sumit Garg wrote:

> On Fri, 23 Feb 2024 at 15:22, Balint Dobszay <balint.dobszay@arm.com> w=
rote:
>>
>> The Trusted Services project provides a framework for developing and
>> deploying device Root of Trust services in FF-A Secure Partitions. The=

>> FF-A SPs are accessible through the FF-A driver, but this doesn't
>> provide a user space interface. The goal of this TEE driver is to make=

>> Trusted Services SPs accessible for user space clients.
>>
>> All TS SPs have the same FF-A UUID, it identifies the RPC protocol use=
d
>> by TS. A TS SP can host one or more services, a service is identified =
by
>> its service UUID. The same type of service cannot be present twice in
>> the same SP. During SP boot each service in an SP is assigned an
>> interface ID, this is just a short ID to simplify message addressing.
>> There is 1:1 mapping between TS SPs and TEE devices, i.e. a separate T=
EE
>> device is registered for each TS SP. This is required since contrary t=
o
>> the generic TEE design where memory is shared with the whole TEE
>> implementation, in case of FF-A, memory is shared with a specific SP. =
A
>> user space client has to be able to separately share memory with each =
SP
>> based on its endpoint ID.
>>
>> Signed-off-by: Balint Dobszay <balint.dobszay@arm.com>
>> ---
>>  drivers/tee/Kconfig               |   1 +
>>  drivers/tee/Makefile              |   1 +
>>  drivers/tee/tstee/Kconfig         |  11 +
>>  drivers/tee/tstee/Makefile        |   3 +
>>  drivers/tee/tstee/core.c          | 490 +++++++++++++++++++++++++++++=
+
>>  drivers/tee/tstee/tstee_private.h |  94 ++++++
>>  include/uapi/linux/tee.h          |   1 +
>>  7 files changed, 601 insertions(+)
>>  create mode 100644 drivers/tee/tstee/Kconfig
>>  create mode 100644 drivers/tee/tstee/Makefile
>>  create mode 100644 drivers/tee/tstee/core.c
>>  create mode 100644 drivers/tee/tstee/tstee_private.h
>>
>> diff --git a/drivers/tee/Kconfig b/drivers/tee/Kconfig
>> index 73a147202e88..61b507c18780 100644
>> --- a/drivers/tee/Kconfig
>> +++ b/drivers/tee/Kconfig
>> @@ -15,5 +15,6 @@ if TEE
>>
>>  source "drivers/tee/optee/Kconfig"
>>  source "drivers/tee/amdtee/Kconfig"
>> +source "drivers/tee/tstee/Kconfig"
>>
>>  endif
>> diff --git a/drivers/tee/Makefile b/drivers/tee/Makefile
>> index 68da044afbfa..5488cba30bd2 100644
>> --- a/drivers/tee/Makefile
>> +++ b/drivers/tee/Makefile
>> @@ -5,3 +5,4 @@ tee-objs +=3D tee_shm.o
>>  tee-objs +=3D tee_shm_pool.o
>>  obj-$(CONFIG_OPTEE) +=3D optee/
>>  obj-$(CONFIG_AMDTEE) +=3D amdtee/
>> +obj-$(CONFIG_ARM_TSTEE) +=3D tstee/
>> diff --git a/drivers/tee/tstee/Kconfig b/drivers/tee/tstee/Kconfig
>> new file mode 100644
>> index 000000000000..d32f91d47398
>> --- /dev/null
>> +++ b/drivers/tee/tstee/Kconfig
>> @@ -0,0 +1,11 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +config ARM_TSTEE
>> +       tristate "Arm Trusted Services TEE driver"
>> +       depends on ARM_FFA_TRANSPORT
>> +       default n
>> +       help
>> +         The Trusted Services project provides a framework for develo=
ping and
>> +         deploying device Root of Trust services in FF-A Secure Parti=
tions.
>> +         This driver provides an interface to make Trusted Services S=
ecure
>> +         Partitions accessible for user space clients, since the FF-A=
 driver
>> +         doesn't implement a user space interface directly.
>> diff --git a/drivers/tee/tstee/Makefile b/drivers/tee/tstee/Makefile
>> new file mode 100644
>> index 000000000000..5227020ebd30
>> --- /dev/null
>> +++ b/drivers/tee/tstee/Makefile
>> @@ -0,0 +1,3 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +arm-tstee-objs :=3D core.o
>> +obj-$(CONFIG_ARM_TSTEE) =3D arm-tstee.o
>> diff --git a/drivers/tee/tstee/core.c b/drivers/tee/tstee/core.c
>> new file mode 100644
>> index 000000000000..2932be017dbe
>> --- /dev/null
>> +++ b/drivers/tee/tstee/core.c
>> @@ -0,0 +1,490 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2023, Arm Limited
>> + */
>> +
>> +#define DRIVER_NAME "Arm TSTEE"
>> +#define pr_fmt(fmt) DRIVER_NAME ": " fmt
>> +
>> +#include <linux/arm_ffa.h>
>> +#include <linux/err.h>
>> +#include <linux/errno.h>
>> +#include <linux/kernel.h>
>> +#include <linux/limits.h>
>> +#include <linux/list.h>
>> +#include <linux/mm.h>
>> +#include <linux/module.h>
>> +#include <linux/scatterlist.h>
>> +#include <linux/slab.h>
>> +#include <linux/stat.h>
>> +#include <linux/tee_drv.h>
>> +#include <linux/types.h>
>> +#include <linux/uaccess.h>
>> +
>> +#include "tstee_private.h"
>> +
>> +#define FFA_DIRECT_REQ_ARG_NUM 5
>> +#define FFA_INVALID_MEM_HANDLE U64_MAX
>> +
>> +static void arg_list_to_ffa_data(const u32 *args,
>> +                                struct ffa_send_direct_data *data)
>> +{
>> +       data->data0 =3D args[0];
>> +       data->data1 =3D args[1];
>> +       data->data2 =3D args[2];
>> +       data->data3 =3D args[3];
>> +       data->data4 =3D args[4];
>> +}
>> +
>> +static void arg_list_from_ffa_data(const struct ffa_send_direct_data =
*data,
>> +                                  u32 *args)
>> +{
>> +       args[0] =3D lower_32_bits(data->data0);
>> +       args[1] =3D lower_32_bits(data->data1);
>> +       args[2] =3D lower_32_bits(data->data2);
>> +       args[3] =3D lower_32_bits(data->data3);
>> +       args[4] =3D lower_32_bits(data->data4);
>> +}
>> +
>> +static void tstee_get_version(struct tee_device *teedev,
>> +                             struct tee_ioctl_version_data *vers)
>> +{
>> +       struct tstee *tstee =3D tee_get_drvdata(teedev);
>> +       struct tee_ioctl_version_data v =3D {
>> +               .impl_id =3D TEE_IMPL_ID_TSTEE,
>> +               /* FF-A endpoint ID only uses the lower 16 bits */
>> +               .impl_caps =3D lower_16_bits(tstee->ffa_dev->vm_id),
>> +               .gen_caps =3D 0,
>> +       };
>> +
>> +       *vers =3D v;
>> +}
>> +
>> +static int tstee_open(struct tee_context *ctx)
>> +{
>> +       struct ts_context_data *ctxdata;
>> +
>> +       ctxdata =3D kzalloc(sizeof(*ctxdata), GFP_KERNEL);
>> +       if (!ctxdata)
>> +               return -ENOMEM;
>> +
>> +       mutex_init(&ctxdata->mutex);
>> +       xa_init_flags(&ctxdata->sess_list, XA_FLAGS_ALLOC);
>> +
>> +       ctx->data =3D ctxdata;
>> +
>> +       return 0;
>> +}
>> +
>> +static void tstee_release(struct tee_context *ctx)
>> +{
>> +       struct ts_context_data *ctxdata =3D ctx->data;
>> +       struct ts_session *sess;
>> +       unsigned long idx;
>> +
>> +       if (!ctxdata)
>> +               return;
>> +
>> +       xa_for_each(&ctxdata->sess_list, idx, sess) {
>> +               xa_erase(&ctxdata->sess_list, idx);
>> +               kfree(sess);
>> +       }
>> +
>> +       xa_destroy(&ctxdata->sess_list);
>> +       mutex_destroy(&ctxdata->mutex);
>> +
>> +       kfree(ctxdata);
>> +       ctx->data =3D NULL;
>> +}
>> +
>> +static int tstee_open_session(struct tee_context *ctx,
>> +                             struct tee_ioctl_open_session_arg *arg,
>> +                             struct tee_param *param __always_unused)=

>> +{
>> +       struct tstee *tstee =3D tee_get_drvdata(ctx->teedev);
>> +       struct ffa_device *ffa_dev =3D tstee->ffa_dev;
>> +       struct ts_context_data *ctxdata =3D ctx->data;
>> +       struct ffa_send_direct_data ffa_data;
>> +       struct ts_session *sess =3D NULL;
>> +       u32 ffa_args[FFA_DIRECT_REQ_ARG_NUM] =3D {};
>> +       u32 sess_id;
>> +       int rc;
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] =3D
>> +               TS_RPC_CTRL_PACK_IFACE_OPCODE(TS_RPC_MGMT_IFACE_ID,
>> +                                             TS_RPC_OP_SERVICE_INFO);=

>> +
>> +       memcpy(ffa_args + TS_RPC_SERVICE_INFO_UUID0, arg->uuid, UUID_S=
IZE);
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       rc =3D ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_=
data);
>> +       if (rc)
>> +               return rc;
>> +
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       if (ffa_args[TS_RPC_SERVICE_INFO_RPC_STATUS] !=3D TS_RPC_OK)
>> +               return -ENODEV;
>> +
>> +       if (ffa_args[TS_RPC_SERVICE_INFO_IFACE] > U8_MAX)
>> +               return -EINVAL;
>> +
>> +       sess =3D kzalloc(sizeof(*sess), GFP_KERNEL);
>> +       if (!sess)
>> +               return -ENOMEM;
>> +
>> +       sess->iface_id =3D ffa_args[TS_RPC_SERVICE_INFO_IFACE];
>> +
>> +       rc =3D xa_alloc(&ctxdata->sess_list, &sess_id, sess, xa_limit_=
32b,
>> +                     GFP_KERNEL);
>> +       if (rc) {
>> +               kfree(sess);
>> +               return rc;
>> +       }
>> +
>> +       arg->session =3D sess_id;
>> +       arg->ret =3D 0;
>> +
>> +       return 0;
>> +}
>> +
>> +static int tstee_close_session(struct tee_context *ctx, u32 session)
>> +{
>> +       struct ts_context_data *ctxdata =3D ctx->data;
>> +       struct ts_session *sess;
>> +
>> +       mutex_lock(&ctxdata->mutex);
>> +       sess =3D xa_erase(&ctxdata->sess_list, session);
>> +       mutex_unlock(&ctxdata->mutex);
>> +       if (!sess)
>> +               return -EINVAL;
>> +
>> +       kfree(sess);
>> +
>> +       return 0;
>> +}
>> +
>> +static int tstee_invoke_func(struct tee_context *ctx,
>> +                            struct tee_ioctl_invoke_arg *arg,
>> +                            struct tee_param *param)
>> +{
>> +       struct tstee *tstee =3D tee_get_drvdata(ctx->teedev);
>> +       struct ffa_device *ffa_dev =3D tstee->ffa_dev;
>> +       struct ts_context_data *ctxdata =3D ctx->data;
>> +       struct ffa_send_direct_data ffa_data;
>> +       struct tee_shm *shm =3D NULL;
>> +       struct ts_session *sess;
>> +       u32 req_len, ffa_args[FFA_DIRECT_REQ_ARG_NUM] =3D {};
>> +       int shm_id, rc;
>> +       u8 iface_id;
>> +       u64 handle;
>> +       u16 opcode;
>> +
>> +       mutex_lock(&ctxdata->mutex);
>> +       sess =3D xa_load(&ctxdata->sess_list, arg->session);
>> +
>> +       /*
>> +        * Do this while holding the mutex to make sure that the sessi=
on wasn't
>> +        * closed meanwhile
>> +        */
>> +       if (sess)
>> +               iface_id =3D sess->iface_id;
>> +
>> +       mutex_unlock(&ctxdata->mutex);
>> +       if (!sess)
>> +               return -EINVAL;
>> +
>
> We can drop usage of mutex here and other places via reusing
> xa_lock(), something like below should work:
>
>         xa_lock(&ctxdata->sess_list);
>
>         sess =3D xa_load(&ctxdata->sess_list, arg->session);
>         if (sess)
>                 iface_id =3D sess->iface_id;
>
>         xa_unlock(&ctxdata->sess_list);

Good point, I'll refactor according to your suggestion.

Regards,
Balint

>> +       opcode =3D lower_16_bits(arg->func);
>> +       shm_id =3D lower_32_bits(param[0].u.value.a);
>> +       req_len =3D lower_32_bits(param[0].u.value.b);
>> +
>> +       if (shm_id !=3D 0) {
>> +               shm =3D tee_shm_get_from_id(ctx, shm_id);
>> +               if (IS_ERR(shm))
>> +                       return PTR_ERR(shm);
>> +
>> +               if (shm->size < req_len) {
>> +                       pr_err("request doesn't fit into shared memory=
 buffer\n");
>> +                       rc =3D -EINVAL;
>> +                       goto out;
>> +               }
>> +
>> +               handle =3D shm->sec_world_id;
>> +       } else {
>> +               handle =3D FFA_INVALID_MEM_HANDLE;
>> +       }
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] =3D TS_RPC_CTRL_PACK_IFACE_OPCODE(if=
ace_id,
>> +                                                                 opco=
de);
>> +       ffa_args[TS_RPC_SERVICE_MEM_HANDLE_LSW] =3D lower_32_bits(hand=
le);
>> +       ffa_args[TS_RPC_SERVICE_MEM_HANDLE_MSW] =3D upper_32_bits(hand=
le);
>> +       ffa_args[TS_RPC_SERVICE_REQ_LEN] =3D req_len;
>> +       ffa_args[TS_RPC_SERVICE_CLIENT_ID] =3D 0;
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       rc =3D ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_=
data);
>> +       if (rc)
>> +               goto out;
>> +
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       if (ffa_args[TS_RPC_SERVICE_RPC_STATUS] !=3D TS_RPC_OK) {
>> +               pr_err("invoke_func rpc status: %d\n",
>> +                      ffa_args[TS_RPC_SERVICE_RPC_STATUS]);
>> +               rc =3D -EINVAL;
>> +               goto out;
>> +       }
>> +
>> +       arg->ret =3D ffa_args[TS_RPC_SERVICE_STATUS];
>> +       if (shm && shm->size >=3D ffa_args[TS_RPC_SERVICE_RESP_LEN])
>> +               param[0].u.value.a =3D ffa_args[TS_RPC_SERVICE_RESP_LE=
N];
>> +
>> +out:
>> +       if (shm)
>> +               tee_shm_put(shm);
>> +
>> +       return rc;
>> +}
>> +
>> +static int tstee_shm_register(struct tee_context *ctx, struct tee_shm=
 *shm,
>> +                             struct page **pages, size_t num_pages,
>> +                             unsigned long start __always_unused)
>> +{
>> +       struct tstee *tstee =3D tee_get_drvdata(ctx->teedev);
>> +       struct ffa_device *ffa_dev =3D tstee->ffa_dev;
>> +       struct ffa_mem_region_attributes mem_attr =3D {
>> +               .receiver =3D tstee->ffa_dev->vm_id,
>> +               .attrs =3D FFA_MEM_RW,
>> +               .flag =3D 0,
>> +       };
>> +       struct ffa_mem_ops_args mem_args =3D {
>> +               .attrs =3D &mem_attr,
>> +               .use_txbuf =3D true,
>> +               .nattrs =3D 1,
>> +               .flags =3D 0,
>> +       };
>> +       struct ffa_send_direct_data ffa_data;
>> +       struct sg_table sgt;
>> +       u32 ffa_args[FFA_DIRECT_REQ_ARG_NUM] =3D {};
>> +       int rc;
>> +
>> +       rc =3D sg_alloc_table_from_pages(&sgt, pages, num_pages, 0,
>> +                                      num_pages * PAGE_SIZE, GFP_KERN=
EL);
>> +       if (rc)
>> +               return rc;
>> +
>> +       mem_args.sg =3D sgt.sgl;
>> +       rc =3D ffa_dev->ops->mem_ops->memory_share(&mem_args);
>> +       sg_free_table(&sgt);
>> +       if (rc)
>> +               return rc;
>> +
>> +       shm->sec_world_id =3D mem_args.g_handle;
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] =3D
>> +                       TS_RPC_CTRL_PACK_IFACE_OPCODE(TS_RPC_MGMT_IFAC=
E_ID,
>> +                                                     TS_RPC_OP_RETRIE=
VE_MEM);
>> +       ffa_args[TS_RPC_RETRIEVE_MEM_HANDLE_LSW] =3D
>> +                       lower_32_bits(shm->sec_world_id);
>> +       ffa_args[TS_RPC_RETRIEVE_MEM_HANDLE_MSW] =3D
>> +                       upper_32_bits(shm->sec_world_id);
>> +       ffa_args[TS_RPC_RETRIEVE_MEM_TAG_LSW] =3D 0;
>> +       ffa_args[TS_RPC_RETRIEVE_MEM_TAG_MSW] =3D 0;
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       rc =3D ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_=
data);
>> +       if (rc) {
>> +               (void)ffa_dev->ops->mem_ops->memory_reclaim(shm->sec_w=
orld_id,
>> +                                                           0);
>> +               return rc;
>> +       }
>> +
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       if (ffa_args[TS_RPC_RETRIEVE_MEM_RPC_STATUS] !=3D TS_RPC_OK) {=

>> +               pr_err("shm_register rpc status: %d\n",
>> +                      ffa_args[TS_RPC_RETRIEVE_MEM_RPC_STATUS]);
>> +               ffa_dev->ops->mem_ops->memory_reclaim(shm->sec_world_i=
d, 0);
>> +               return -EINVAL;
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>> +static int tstee_shm_unregister(struct tee_context *ctx, struct tee_s=
hm *shm)
>> +{
>> +       struct tstee *tstee =3D tee_get_drvdata(ctx->teedev);
>> +       struct ffa_device *ffa_dev =3D tstee->ffa_dev;
>> +       struct ffa_send_direct_data ffa_data;
>> +       u32 ffa_args[FFA_DIRECT_REQ_ARG_NUM] =3D {};
>> +       int rc;
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] =3D
>> +                       TS_RPC_CTRL_PACK_IFACE_OPCODE(TS_RPC_MGMT_IFAC=
E_ID,
>> +                                                     TS_RPC_OP_RELINQ=
_MEM);
>> +       ffa_args[TS_RPC_RELINQ_MEM_HANDLE_LSW] =3D
>> +                       lower_32_bits(shm->sec_world_id);
>> +       ffa_args[TS_RPC_RELINQ_MEM_HANDLE_MSW] =3D
>> +                       upper_32_bits(shm->sec_world_id);
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       rc =3D ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_=
data);
>> +       if (rc)
>> +               return rc;
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       if (ffa_args[TS_RPC_RELINQ_MEM_RPC_STATUS] !=3D TS_RPC_OK) {
>> +               pr_err("shm_unregister rpc status: %d\n",
>> +                      ffa_args[TS_RPC_RELINQ_MEM_RPC_STATUS]);
>> +               return -EINVAL;
>> +       }
>> +
>> +       rc =3D ffa_dev->ops->mem_ops->memory_reclaim(shm->sec_world_id=
, 0);
>> +
>> +       return rc;
>> +}
>> +
>> +static const struct tee_driver_ops tstee_ops =3D {
>> +       .get_version =3D tstee_get_version,
>> +       .open =3D tstee_open,
>> +       .release =3D tstee_release,
>> +       .open_session =3D tstee_open_session,
>> +       .close_session =3D tstee_close_session,
>> +       .invoke_func =3D tstee_invoke_func,
>> +       .shm_register =3D tstee_shm_register,
>> +       .shm_unregister =3D tstee_shm_unregister,
>> +};
>> +
>> +static const struct tee_desc tstee_desc =3D {
>> +       .name =3D "tstee-clnt",
>> +       .ops =3D &tstee_ops,
>> +       .owner =3D THIS_MODULE,
>> +};
>> +
>> +static int pool_op_alloc(struct tee_shm_pool *pool, struct tee_shm *s=
hm,
>> +                        size_t size, size_t align)
>> +{
>> +       return tee_shm_pool_op_alloc_helper(pool, shm, size, align,
>> +                                           tstee_shm_register);
>> +}
>> +
>> +static void pool_op_free(struct tee_shm_pool *pool, struct tee_shm *s=
hm)
>> +{
>> +       tee_shm_pool_op_free_helper(pool, shm, tstee_shm_unregister);
>> +}
>> +
>> +static void pool_op_destroy_pool(struct tee_shm_pool *pool)
>> +{
>> +       kfree(pool);
>> +}
>> +
>> +static const struct tee_shm_pool_ops pool_ops =3D {
>> +       .alloc =3D pool_op_alloc,
>> +       .free =3D pool_op_free,
>> +       .destroy_pool =3D pool_op_destroy_pool,
>> +};
>> +
>> +static struct tee_shm_pool *tstee_create_shm_pool(void)
>> +{
>> +       struct tee_shm_pool *pool =3D kzalloc(sizeof(*pool), GFP_KERNE=
L);
>> +
>> +       if (!pool)
>> +               return ERR_PTR(-ENOMEM);
>> +
>> +       pool->ops =3D &pool_ops;
>> +
>> +       return pool;
>> +}
>> +
>> +static bool tstee_check_rpc_compatible(struct ffa_device *ffa_dev)
>> +{
>> +       struct ffa_send_direct_data ffa_data;
>> +       u32 ffa_args[FFA_DIRECT_REQ_ARG_NUM] =3D {};
>> +
>> +       ffa_args[TS_RPC_CTRL_REG] =3D
>> +                       TS_RPC_CTRL_PACK_IFACE_OPCODE(TS_RPC_MGMT_IFAC=
E_ID,
>> +                                                     TS_RPC_OP_GET_VE=
RSION);
>> +
>> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
>> +       if (ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_dat=
a))
>> +               return false;
>> +
>> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
>> +
>> +       return ffa_args[TS_RPC_GET_VERSION_RESP] =3D=3D TS_RPC_PROTOCO=
L_VERSION;
>> +}
>> +
>> +static int tstee_probe(struct ffa_device *ffa_dev)
>> +{
>> +       struct tstee *tstee;
>> +       int rc;
>> +
>> +       ffa_dev->ops->msg_ops->mode_32bit_set(ffa_dev);
>> +
>> +       if (!tstee_check_rpc_compatible(ffa_dev))
>> +               return -EINVAL;
>> +
>> +       tstee =3D kzalloc(sizeof(*tstee), GFP_KERNEL);
>> +       if (!tstee)
>> +               return -ENOMEM;
>> +
>> +       tstee->ffa_dev =3D ffa_dev;
>> +
>> +       tstee->pool =3D tstee_create_shm_pool();
>> +       if (IS_ERR(tstee->pool)) {
>> +               rc =3D PTR_ERR(tstee->pool);
>> +               tstee->pool =3D NULL;
>> +               goto err_free_tstee;
>> +       }
>> +
>> +       tstee->teedev =3D tee_device_alloc(&tstee_desc, NULL, tstee->p=
ool, tstee);
>> +       if (IS_ERR(tstee->teedev)) {
>> +               rc =3D PTR_ERR(tstee->teedev);
>> +               tstee->teedev =3D NULL;
>> +               goto err_free_pool;
>> +       }
>> +
>> +       rc =3D tee_device_register(tstee->teedev);
>> +       if (rc)
>> +               goto err_unreg_teedev;
>> +
>> +       ffa_dev_set_drvdata(ffa_dev, tstee);
>> +
>> +       return 0;
>> +
>> +err_unreg_teedev:
>> +       tee_device_unregister(tstee->teedev);
>> +err_free_pool:
>> +       tee_shm_pool_free(tstee->pool);
>> +err_free_tstee:
>> +       kfree(tstee);
>> +       return rc;
>> +}
>> +
>> +static void tstee_remove(struct ffa_device *ffa_dev)
>> +{
>> +       struct tstee *tstee =3D ffa_dev->dev.driver_data;
>> +
>> +       tee_device_unregister(tstee->teedev);
>> +       tee_shm_pool_free(tstee->pool);
>> +       kfree(tstee);
>> +}
>> +
>> +static const struct ffa_device_id tstee_device_ids[] =3D {
>> +       /* TS RPC protocol UUID: bdcd76d7-825e-4751-963b-86d4f84943ac =
*/
>> +       { TS_RPC_UUID },
>> +       {}
>> +};
>> +
>> +static struct ffa_driver tstee_driver =3D {
>> +       .name =3D "arm_tstee",
>> +       .probe =3D tstee_probe,
>> +       .remove =3D tstee_remove,
>> +       .id_table =3D tstee_device_ids,
>> +};
>> +
>> +module_ffa_driver(tstee_driver);
>> +
>> +MODULE_AUTHOR("Balint Dobszay <balint.dobszay@arm.com>");
>> +MODULE_DESCRIPTION("Arm Trusted Services TEE driver");
>> +MODULE_LICENSE("GPL");
>> diff --git a/drivers/tee/tstee/tstee_private.h b/drivers/tee/tstee/tst=
ee_private.h
>> new file mode 100644
>> index 000000000000..6d24cf0dbbc2
>> --- /dev/null
>> +++ b/drivers/tee/tstee/tstee_private.h
>> @@ -0,0 +1,94 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (c) 2023, Arm Limited
>> + */
>> +
>> +#ifndef TSTEE_PRIVATE_H
>> +#define TSTEE_PRIVATE_H
>> +
>> +#include <linux/arm_ffa.h>
>> +#include <linux/bitops.h>
>> +#include <linux/tee_drv.h>
>> +#include <linux/types.h>
>> +#include <linux/uuid.h>
>> +#include <linux/xarray.h>
>> +
>> +/*
>> + * The description of the ABI implemented in this file is available a=
t
>> + * https://trusted-services.readthedocs.io/en/v1.0.0/developer/servic=
e-access-protocols.html#abi
>> + */
>> +
>> +/* UUID of this protocol */
>> +#define TS_RPC_UUID UUID_INIT(0xbdcd76d7, 0x825e, 0x4751, \
>> +                             0x96, 0x3b, 0x86, 0xd4, 0xf8, 0x49, 0x43=
, 0xac)
>> +
>> +/* Protocol version*/
>> +#define TS_RPC_PROTOCOL_VERSION                (1)
>> +
>> +/* Status codes */
>> +#define TS_RPC_OK                      (0)
>> +
>> +/* RPC control register */
>> +#define TS_RPC_CTRL_REG                        (0)
>> +#define OPCODE_MASK                    GENMASK(15, 0)
>> +#define IFACE_ID_MASK                  GENMASK(23, 16)
>> +#define TS_RPC_CTRL_OPCODE(x)          ((u16)(FIELD_GET(OPCODE_MASK, =
(x))))
>> +#define TS_RPC_CTRL_IFACE_ID(x)                ((u8)(FIELD_GET(IFACE_=
ID_MASK, (x))))
>> +#define TS_RPC_CTRL_PACK_IFACE_OPCODE(i, o)    \
>> +       (FIELD_PREP(IFACE_ID_MASK, (i)) | FIELD_PREP(OPCODE_MASK, (o))=
)
>> +#define TS_RPC_CTRL_SAP_RC             BIT(30)
>> +#define TS_RPC_CTRL_SAP_ERR            BIT(31)
>> +
>> +/* Interface ID for RPC management operations */
>> +#define TS_RPC_MGMT_IFACE_ID           (0xff)
>> +
>> +/* Management calls */
>> +#define TS_RPC_OP_GET_VERSION          (0x0000)
>> +#define TS_RPC_GET_VERSION_RESP                (1)
>> +
>> +#define TS_RPC_OP_RETRIEVE_MEM         (0x0001)
>> +#define TS_RPC_RETRIEVE_MEM_HANDLE_LSW (1)
>> +#define TS_RPC_RETRIEVE_MEM_HANDLE_MSW (2)
>> +#define TS_RPC_RETRIEVE_MEM_TAG_LSW    (3)
>> +#define TS_RPC_RETRIEVE_MEM_TAG_MSW    (4)
>> +#define TS_RPC_RETRIEVE_MEM_RPC_STATUS (1)
>> +
>> +#define TS_RPC_OP_RELINQ_MEM           (0x0002)
>> +#define TS_RPC_RELINQ_MEM_HANDLE_LSW   (1)
>> +#define TS_RPC_RELINQ_MEM_HANDLE_MSW   (2)
>> +#define TS_RPC_RELINQ_MEM_RPC_STATUS   (1)
>> +
>> +#define TS_RPC_OP_SERVICE_INFO         (0x0003)
>> +#define TS_RPC_SERVICE_INFO_UUID0      (1)
>> +#define TS_RPC_SERVICE_INFO_UUID1      (2)
>> +#define TS_RPC_SERVICE_INFO_UUID2      (3)
>> +#define TS_RPC_SERVICE_INFO_UUID3      (4)
>> +#define TS_RPC_SERVICE_INFO_RPC_STATUS (1)
>> +#define TS_RPC_SERVICE_INFO_IFACE      (2)
>> +
>> +/* Service call */
>> +#define TS_RPC_SERVICE_MEM_HANDLE_LSW  (1)
>> +#define TS_RPC_SERVICE_MEM_HANDLE_MSW  (2)
>> +#define TS_RPC_SERVICE_REQ_LEN         (3)
>> +#define TS_RPC_SERVICE_CLIENT_ID       (4)
>> +#define TS_RPC_SERVICE_RPC_STATUS      (1)
>> +#define TS_RPC_SERVICE_STATUS          (2)
>> +#define TS_RPC_SERVICE_RESP_LEN                (3)
>> +
>> +struct tstee {
>> +       struct ffa_device *ffa_dev;
>> +       struct tee_device *teedev;
>> +       struct tee_shm_pool *pool;
>> +};
>> +
>> +struct ts_session {
>> +       u8 iface_id;
>> +};
>> +
>> +struct ts_context_data {
>> +       struct xarray sess_list;
>> +       /* Serializes access to the session list */
>> +       struct mutex mutex;
>> +};
>> +
>> +#endif /* TSTEE_PRIVATE_H */
>> diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
>> index 23e57164693c..d0430bee8292 100644
>> --- a/include/uapi/linux/tee.h
>> +++ b/include/uapi/linux/tee.h
>> @@ -56,6 +56,7 @@
>>   */
>>  #define TEE_IMPL_ID_OPTEE      1
>>  #define TEE_IMPL_ID_AMDTEE     2
>> +#define TEE_IMPL_ID_TSTEE      3
>>
>>  /*
>>   * OP-TEE specific capabilities
>> --
>> 2.34.1
>>