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References: <20240213145239.379875-1-balint.dobszay@arm.com> <20240213145239.379875-3-balint.dobszay@arm.com>
In-Reply-To: <20240213145239.379875-3-balint.dobszay@arm.com>
From: Jens Wiklander <jens.wiklander@linaro.org>
Date: Thu, 15 Feb 2024 11:00:36 +0100
Message-ID: <CAHUa44Fzr5zMRkMZUfPNOu+nbAkp+n2FcrgrJ-U8R__qS42fzw@mail.gmail.com>
Subject: Re: [PATCH 2/3] tee: tstee: Add Trusted Services TEE driver
To: Balint Dobszay <balint.dobszay@arm.com>
Cc: op-tee@lists.trustedfirmware.org, linux-doc@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, 
	sumit.garg@linaro.org, corbet@lwn.net, sudeep.holla@arm.com, 
	gyorgy.szing@arm.com
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Hi Balint,

On Tue, Feb 13, 2024 at 3:54=E2=80=AFPM Balint Dobszay <balint.dobszay@arm.=
com> wrote:
>
> 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 used
> 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 TEE
> device is registered for each TS SP. This is required since contrary to
> 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          | 501 ++++++++++++++++++++++++++++++
>  drivers/tee/tstee/tstee_private.h |  92 ++++++
>  include/uapi/linux/tee.h          |   1 +
>  7 files changed, 610 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-$(CONFIG_ARM_TSTEE) +=3D tstee/
> diff --git a/drivers/tee/tstee/Kconfig b/drivers/tee/tstee/Kconfig
> new file mode 100644
> index 000000000000..d32f91d47398
> --- /dev/null
> +++ b/drivers/tee/tstee/Kconfig
> @@ -0,0 +1,11 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +config ARM_TSTEE
> +       tristate "Arm Trusted Services TEE driver"
> +       depends on ARM_FFA_TRANSPORT
> +       default n
> +       help
> +         The Trusted Services project provides a framework for developin=
g and
> +         deploying device Root of Trust services in FF-A Secure Partitio=
ns.
> +         This driver provides an interface to make Trusted Services Secu=
re
> +         Partitions accessible for user space clients, since the FF-A dr=
iver
> +         doesn't implement a user space interface directly.
> diff --git a/drivers/tee/tstee/Makefile b/drivers/tee/tstee/Makefile
> new file mode 100644
> index 000000000000..5227020ebd30
> --- /dev/null
> +++ b/drivers/tee/tstee/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +arm-tstee-objs :=3D core.o
> +obj-$(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..8d6bbe4d03ed
> --- /dev/null
> +++ b/drivers/tee/tstee/core.c
> @@ -0,0 +1,501 @@
> +// 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)

The preferred limit on the length of a single line is 80 columns
https://www.kernel.org/doc/html/latest/process/coding-style.html#breaking-l=
ong-lines-and-strings


> +{
> +       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 *da=
ta, 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_ioct=
l_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);
> +       idr_init(&ctxdata->sess_ids);
> +       INIT_LIST_HEAD(&ctxdata->sess_list);
> +
> +       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, *sess_tmp;
> +
> +       if (!ctxdata)
> +               return;
> +
> +       list_for_each_entry_safe(sess, sess_tmp, &ctxdata->sess_list, lis=
t_node) {
> +               list_del(&sess->list_node);
> +               idr_remove(&ctxdata->sess_ids, sess->session_id);
> +               kfree(sess);
> +       }
> +
> +       idr_destroy(&ctxdata->sess_ids);
> +       mutex_destroy(&ctxdata->mutex);
> +
> +       kfree(ctxdata);
> +       ctx->data =3D NULL;
> +}
> +
> +static struct ts_session *find_session(struct ts_context_data *ctxdata, =
u32 session_id)
> +{
> +       struct ts_session *sess;
> +
> +       list_for_each_entry(sess, &ctxdata->sess_list, list_node)
> +               if (sess->session_id =3D=3D session_id)
> +                       return sess;

Since you have an idr, why not use idr_find() instead?

> +
> +       return 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 {};
> +       int sess_id;
> +       int rc;
> +
> +       ffa_args[TS_RPC_CTRL_REG] =3D TS_RPC_CTRL_PACK_IFACE_OPCODE(TS_RP=
C_MGMT_IFACE_ID,
> +                                                                 TS_RPC_=
OP_SERVICE_INFO);
> +
> +       memcpy((u8 *)(ffa_args + TS_RPC_SERVICE_INFO_UUID0), arg->uuid, U=
UID_SIZE);

Is the cast needed?

> +
> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
> +       rc =3D ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_dat=
a);
> +       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_id =3D idr_alloc(&ctxdata->sess_ids, sess, 1, 0, GFP_KERNEL)=
;

This needs to be protected by the mutex.

> +       if (sess_id < 0) {
> +               kfree(sess);
> +               return sess_id;
> +       }
> +
> +       sess->session_id =3D sess_id;
> +       sess->iface_id =3D ffa_args[TS_RPC_SERVICE_INFO_IFACE];
> +
> +       mutex_lock(&ctxdata->mutex);
> +       list_add(&sess->list_node, &ctxdata->sess_list);
> +       mutex_unlock(&ctxdata->mutex);
> +
> +       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 find_session(ctxdata, session);
> +       if (sess)
> +               list_del(&sess->list_node);
> +
> +       mutex_unlock(&ctxdata->mutex);
> +
> +       if (!sess)
> +               return -EINVAL;
> +
> +       idr_remove(&ctxdata->sess_ids, sess->session_id);
> +       kfree(sess);
> +
> +       return 0;
> +}
> +
> +static int tstee_invoke_func(struct tee_context *ctx, struct tee_ioctl_i=
nvoke_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 find_session(ctxdata, arg->session);
> +
> +       /* Do this while holding the mutex to make sure that the session =
wasn't closed meanwhile */
> +       if (sess)
> +               iface_id =3D sess->iface_id;
> +
> +       mutex_unlock(&ctxdata->mutex);
> +       if (!sess)
> +               return -EINVAL;
> +
> +       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 bu=
ffer\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(iface=
_id, opcode);
> +       ffa_args[TS_RPC_SERVICE_MEM_HANDLE_LSW] =3D lower_32_bits(handle)=
;
> +       ffa_args[TS_RPC_SERVICE_MEM_HANDLE_MSW] =3D upper_32_bits(handle)=
;
> +       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_dat=
a);
> +       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_SE=
RVICE_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_LEN];
> +
> +out:
> +       if (shm)
> +               tee_shm_put(shm);
> +
> +       return rc;
> +}
> +
> +static int tstee_shm_register(struct tee_context *ctx, struct tee_shm *s=
hm, struct page **pages,
> +                             size_t num_pages, unsigned long start __alw=
ays_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_p=
ages * PAGE_SIZE,
> +                                      GFP_KERNEL);
> +       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_RP=
C_MGMT_IFACE_ID,
> +                                                                 TS_RPC_=
OP_RETRIEVE_MEM);
> +       ffa_args[TS_RPC_RETRIEVE_MEM_HANDLE_LSW] =3D lower_32_bits(shm->s=
ec_world_id);
> +       ffa_args[TS_RPC_RETRIEVE_MEM_HANDLE_MSW] =3D upper_32_bits(shm->s=
ec_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_dat=
a);
> +       if (rc) {
> +               (void)ffa_dev->ops->mem_ops->memory_reclaim(shm->sec_worl=
d_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_R=
ETRIEVE_MEM_RPC_STATUS]);
> +               ffa_dev->ops->mem_ops->memory_reclaim(shm->sec_world_id, =
0);
> +               return -EINVAL;
> +       }
> +
> +       return 0;
> +}
> +
> +static int tstee_shm_unregister(struct tee_context *ctx, struct tee_shm =
*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_RP=
C_MGMT_IFACE_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_dat=
a);
> +       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 *shm,=
 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 *shm)
> +{
> +       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_KERNEL);
> +
> +       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_RP=
C_MGMT_IFACE_ID,
> +                                                                 TS_RPC_=
OP_GET_VERSION);
> +
> +       arg_list_to_ffa_data(ffa_args, &ffa_data);
> +       if (ffa_dev->ops->msg_ops->sync_send_receive(ffa_dev, &ffa_data))
> +               return false;
> +
> +       arg_list_from_ffa_data(&ffa_data, ffa_args);
> +
> +       return ffa_args[TS_RPC_GET_VERSION_RESP] =3D=3D TS_RPC_PROTOCOL_V=
ERSION;
> +}
> +
> +static void tstee_deinit_common(struct tstee *tstee)
> +{
> +       tee_device_unregister(tstee->teedev);
> +       if (tstee->pool)
> +               tee_shm_pool_free(tstee->pool);
> +
> +       kfree(tstee);
> +}
> +
> +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;
> +       }
> +
> +       tstee->teedev =3D tee_device_alloc(&tstee_desc, NULL, tstee->pool=
, tstee);
> +       if (IS_ERR(tstee->teedev)) {
> +               rc =3D PTR_ERR(tstee->teedev);
> +               tstee->teedev =3D NULL;
> +               goto err;
> +       }
> +
> +       rc =3D tee_device_register(tstee->teedev);
> +       if (rc)
> +               goto err;
> +
> +       ffa_dev_set_drvdata(ffa_dev, tstee);
> +
> +       pr_info("driver initialized for endpoint 0x%x\n", ffa_dev->vm_id)=
;
> +
> +       return 0;
> +
> +err:
> +       tstee_deinit_common(tstee);
> +       return rc;
> +}
> +
> +static void tstee_remove(struct ffa_device *ffa_dev)
> +{
> +       tstee_deinit_common(ffa_dev->dev.driver_data);
> +}
> +
> +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,
> +};
> +
> +static int __init mod_init(void)
> +{
> +       return ffa_register(&tstee_driver);
> +}
> +module_init(mod_init)
> +
> +static void __exit mod_exit(void)
> +{
> +       ffa_unregister(&tstee_driver);
> +}
> +module_exit(mod_exit)
> +
> +MODULE_ALIAS("arm-tstee");
> +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/tstee_=
private.h
> new file mode 100644
> index 000000000000..81eeda220a5c
> --- /dev/null
> +++ b/drivers/tee/tstee/tstee_private.h
> @@ -0,0 +1,92 @@
> +/* 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/idr.h>
> +#include <linux/tee_drv.h>
> +#include <linux/types.h>
> +#include <linux/uuid.h>
> +
> +/* UUID of this protocol */

It would be nice to have a link or reference to the description of the ABI.

> +#define TS_RPC_UUID UUID_INIT(0xbdcd76d7, 0x825e, 0x4751, \
> +                             0x96, 0x3b, 0x86, 0xd4, 0xf8, 0x49, 0x43, 0=
xac)
> +
> +/* 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 {
> +       struct list_head list_node;
> +       u32 session_id;
> +       u8 iface_id;
> +};
> +
> +struct ts_context_data {
> +       struct list_head sess_list;
> +       struct idr sess_ids;

Why do you need both a linked list and an IDR? Wouldn't the IDR be enough?

Cheers,
Jens

> +       /* Serializes access to this struct */
> +       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
>