Merge tag 'system-thread-for-v6.8' of https://git.linaro.org/people/jens.wiklander/linux-tee into soc/drivers

OP-TEE add reserved system thread

Add support for a reserved system thread in the SMC-ABI of the OP-TEE driver.
SCMI with OP-TEE transport uses this to guarantee that it will always have
a thread available in the secure world.

* tag 'system-thread-for-v6.8' of https://git.linaro.org/people/jens.wiklander/linux-tee:
  firmware: arm_scmi: optee: use optee system invocation
  tee: optee: support tracking system threads
  tee: system session
  tee: optee: system thread call property

Link: https://lore.kernel.org/r/20231211102600.GA571787@rayden
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

8 files changed, 211 insertions, 27 deletions

diff --git a/drivers/firmware/arm_scmi/optee.c b/drivers/firmware/arm_scmi/optee.c
index e123de6e8c67..25bfb465484d 100644
--- a/drivers/firmware/arm_scmi/optee.c
+++ b/drivers/firmware/arm_scmi/optee.c
@@ -440,6 +440,10 @@ static int scmi_optee_chan_setup(struct scmi_chan_info *cinfo, struct device *de
 	if (ret)
 		goto err_free_shm;
 
+	ret = tee_client_system_session(scmi_optee_private->tee_ctx, channel->tee_session);
+	if (ret)
+		dev_warn(dev, "Could not switch to system session, do best effort\n");
+
 	ret = get_channel(channel);
 	if (ret)
 		goto err_close_sess;
diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c
index df5fb5410b72..b04c49c69619 100644
--- a/drivers/tee/optee/call.c
+++ b/drivers/tee/optee/call.c
@@ -39,9 +39,29 @@ struct optee_shm_arg_entry {
 	DECLARE_BITMAP(map, MAX_ARG_COUNT_PER_ENTRY);
 };
 
+void optee_cq_init(struct optee_call_queue *cq, int thread_count)
+{
+	mutex_init(&cq->mutex);
+	INIT_LIST_HEAD(&cq->waiters);
+
+	/*
+	 * If cq->total_thread_count is 0 then we're not trying to keep
+	 * track of how many free threads we have, instead we're relying on
+	 * the secure world to tell us when we're out of thread and have to
+	 * wait for another thread to become available.
+	 */
+	cq->total_thread_count = thread_count;
+	cq->free_thread_count = thread_count;
+}
+
 void optee_cq_wait_init(struct optee_call_queue *cq,
-			struct optee_call_waiter *w)
+			struct optee_call_waiter *w, bool sys_thread)
 {
+	unsigned int free_thread_threshold;
+	bool need_wait = false;
+
+	memset(w, 0, sizeof(*w));
+
 	/*
 	 * We're preparing to make a call to secure world. In case we can't
 	 * allocate a thread in secure world we'll end up waiting in
@@ -60,8 +80,38 @@ void optee_cq_wait_init(struct optee_call_queue *cq,
 	 */
 	init_completion(&w->c);
 	list_add_tail(&w->list_node, &cq->waiters);
+	w->sys_thread = sys_thread;
+
+	if (cq->total_thread_count) {
+		if (sys_thread || !cq->sys_thread_req_count)
+			free_thread_threshold = 0;
+		else
+			free_thread_threshold = 1;
+
+		if (cq->free_thread_count > free_thread_threshold)
+			cq->free_thread_count--;
+		else
+			need_wait = true;
+	}
 
 	mutex_unlock(&cq->mutex);
+
+	while (need_wait) {
+		optee_cq_wait_for_completion(cq, w);
+		mutex_lock(&cq->mutex);
+
+		if (sys_thread || !cq->sys_thread_req_count)
+			free_thread_threshold = 0;
+		else
+			free_thread_threshold = 1;
+
+		if (cq->free_thread_count > free_thread_threshold) {
+			cq->free_thread_count--;
+			need_wait = false;
+		}
+
+		mutex_unlock(&cq->mutex);
+	}
 }
 
 void optee_cq_wait_for_completion(struct optee_call_queue *cq,
@@ -83,6 +133,14 @@ static void optee_cq_complete_one(struct optee_call_queue *cq)
 {
 	struct optee_call_waiter *w;
 
+	/* Wake a waiting system session if any, prior to a normal session */
+	list_for_each_entry(w, &cq->waiters, list_node) {
+		if (w->sys_thread && !completion_done(&w->c)) {
+			complete(&w->c);
+			return;
+		}
+	}
+
 	list_for_each_entry(w, &cq->waiters, list_node) {
 		if (!completion_done(&w->c)) {
 			complete(&w->c);
@@ -104,6 +162,8 @@ void optee_cq_wait_final(struct optee_call_queue *cq,
 	/* Get out of the list */
 	list_del(&w->list_node);
 
+	cq->free_thread_count++;
+
 	/* Wake up one eventual waiting task */
 	optee_cq_complete_one(cq);
 
@@ -119,6 +179,28 @@ void optee_cq_wait_final(struct optee_call_queue *cq,
 	mutex_unlock(&cq->mutex);
 }
 
+/* Count registered system sessions to reserved a system thread or not */
+static bool optee_cq_incr_sys_thread_count(struct optee_call_queue *cq)
+{
+	if (cq->total_thread_count <= 1)
+		return false;
+
+	mutex_lock(&cq->mutex);
+	cq->sys_thread_req_count++;
+	mutex_unlock(&cq->mutex);
+
+	return true;
+}
+
+static void optee_cq_decr_sys_thread_count(struct optee_call_queue *cq)
+{
+	mutex_lock(&cq->mutex);
+	cq->sys_thread_req_count--;
+	/* If there's someone waiting, let it resume */
+	optee_cq_complete_one(cq);
+	mutex_unlock(&cq->mutex);
+}
+
 /* Requires the filpstate mutex to be held */
 static struct optee_session *find_session(struct optee_context_data *ctxdata,
 					  u32 session_id)
@@ -328,7 +410,8 @@ int optee_open_session(struct tee_context *ctx,
 		goto out;
 	}
 
-	if (optee->ops->do_call_with_arg(ctx, shm, offs)) {
+	if (optee->ops->do_call_with_arg(ctx, shm, offs,
+					 sess->use_sys_thread)) {
 		msg_arg->ret = TEEC_ERROR_COMMUNICATION;
 		msg_arg->ret_origin = TEEC_ORIGIN_COMMS;
 	}
@@ -360,7 +443,29 @@ out:
 	return rc;
 }
 
-int optee_close_session_helper(struct tee_context *ctx, u32 session)
+int optee_system_session(struct tee_context *ctx, u32 session)
+{
+	struct optee *optee = tee_get_drvdata(ctx->teedev);
+	struct optee_context_data *ctxdata = ctx->data;
+	struct optee_session *sess;
+	int rc = -EINVAL;
+
+	mutex_lock(&ctxdata->mutex);
+
+	sess = find_session(ctxdata, session);
+	if (sess && (sess->use_sys_thread ||
+		     optee_cq_incr_sys_thread_count(&optee->call_queue))) {
+		sess->use_sys_thread = true;
+		rc = 0;
+	}
+
+	mutex_unlock(&ctxdata->mutex);
+
+	return rc;
+}
+
+int optee_close_session_helper(struct tee_context *ctx, u32 session,
+			       bool system_thread)
 {
 	struct optee *optee = tee_get_drvdata(ctx->teedev);
 	struct optee_shm_arg_entry *entry;
@@ -374,10 +479,13 @@ int optee_close_session_helper(struct tee_context *ctx, u32 session)
 
 	msg_arg->cmd = OPTEE_MSG_CMD_CLOSE_SESSION;
 	msg_arg->session = session;
-	optee->ops->do_call_with_arg(ctx, shm, offs);
+	optee->ops->do_call_with_arg(ctx, shm, offs, system_thread);
 
 	optee_free_msg_arg(ctx, entry, offs);
 
+	if (system_thread)
+		optee_cq_decr_sys_thread_count(&optee->call_queue);
+
 	return 0;
 }
 
@@ -385,6 +493,7 @@ int optee_close_session(struct tee_context *ctx, u32 session)
 {
 	struct optee_context_data *ctxdata = ctx->data;
 	struct optee_session *sess;
+	bool system_thread;
 
 	/* Check that the session is valid and remove it from the list */
 	mutex_lock(&ctxdata->mutex);
@@ -394,9 +503,10 @@ int optee_close_session(struct tee_context *ctx, u32 session)
 	mutex_unlock(&ctxdata->mutex);
 	if (!sess)
 		return -EINVAL;
+	system_thread = sess->use_sys_thread;
 	kfree(sess);
 
-	return optee_close_session_helper(ctx, session);
+	return optee_close_session_helper(ctx, session, system_thread);
 }
 
 int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg,
@@ -408,12 +518,15 @@ int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg,
 	struct optee_msg_arg *msg_arg;
 	struct optee_session *sess;
 	struct tee_shm *shm;
+	bool system_thread;
 	u_int offs;
 	int rc;
 
 	/* Check that the session is valid */
 	mutex_lock(&ctxdata->mutex);
 	sess = find_session(ctxdata, arg->session);
+	if (sess)
+		system_thread = sess->use_sys_thread;
 	mutex_unlock(&ctxdata->mutex);
 	if (!sess)
 		return -EINVAL;
@@ -432,7 +545,7 @@ int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg,
 	if (rc)
 		goto out;
 
-	if (optee->ops->do_call_with_arg(ctx, shm, offs)) {
+	if (optee->ops->do_call_with_arg(ctx, shm, offs, system_thread)) {
 		msg_arg->ret = TEEC_ERROR_COMMUNICATION;
 		msg_arg->ret_origin = TEEC_ORIGIN_COMMS;
 	}
@@ -457,12 +570,15 @@ int optee_cancel_req(struct tee_context *ctx, u32 cancel_id, u32 session)
 	struct optee_shm_arg_entry *entry;
 	struct optee_msg_arg *msg_arg;
 	struct optee_session *sess;
+	bool system_thread;
 	struct tee_shm *shm;
 	u_int offs;
 
 	/* Check that the session is valid */
 	mutex_lock(&ctxdata->mutex);
 	sess = find_session(ctxdata, session);
+	if (sess)
+		system_thread = sess->use_sys_thread;
 	mutex_unlock(&ctxdata->mutex);
 	if (!sess)
 		return -EINVAL;
@@ -474,7 +590,7 @@ int optee_cancel_req(struct tee_context *ctx, u32 cancel_id, u32 session)
 	msg_arg->cmd = OPTEE_MSG_CMD_CANCEL;
 	msg_arg->session = session;
 	msg_arg->cancel_id = cancel_id;
-	optee->ops->do_call_with_arg(ctx, shm, offs);
+	optee->ops->do_call_with_arg(ctx, shm, offs, system_thread);
 
 	optee_free_msg_arg(ctx, entry, offs);
 	return 0;
diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index 2a258bd3b6b5..d01ca47f7bde 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -129,7 +129,8 @@ int optee_open(struct tee_context *ctx, bool cap_memref_null)
 
 static void optee_release_helper(struct tee_context *ctx,
 				 int (*close_session)(struct tee_context *ctx,
-						      u32 session))
+						      u32 session,
+						      bool system_thread))
 {
 	struct optee_context_data *ctxdata = ctx->data;
 	struct optee_session *sess;
@@ -141,7 +142,7 @@ static void optee_release_helper(struct tee_context *ctx,
 	list_for_each_entry_safe(sess, sess_tmp, &ctxdata->sess_list,
 				 list_node) {
 		list_del(&sess->list_node);
-		close_session(ctx, sess->session_id);
+		close_session(ctx, sess->session_id, sess->use_sys_thread);
 		kfree(sess);
 	}
 	kfree(ctxdata);
diff --git a/drivers/tee/optee/ffa_abi.c b/drivers/tee/optee/ffa_abi.c
index 0828240f27e6..d73396ed5b93 100644
--- a/drivers/tee/optee/ffa_abi.c
+++ b/drivers/tee/optee/ffa_abi.c
@@ -528,7 +528,8 @@ static void optee_handle_ffa_rpc(struct tee_context *ctx, struct optee *optee,
 
 static int optee_ffa_yielding_call(struct tee_context *ctx,
 				   struct ffa_send_direct_data *data,
-				   struct optee_msg_arg *rpc_arg)
+				   struct optee_msg_arg *rpc_arg,
+				   bool system_thread)
 {
 	struct optee *optee = tee_get_drvdata(ctx->teedev);
 	struct ffa_device *ffa_dev = optee->ffa.ffa_dev;
@@ -541,7 +542,7 @@ static int optee_ffa_yielding_call(struct tee_context *ctx,
 	int rc;
 
 	/* Initialize waiter */
-	optee_cq_wait_init(&optee->call_queue, &w);
+	optee_cq_wait_init(&optee->call_queue, &w, system_thread);
 	while (true) {
 		rc = msg_ops->sync_send_receive(ffa_dev, data);
 		if (rc)
@@ -604,6 +605,7 @@ done:
  * @ctx:	calling context
  * @shm:	shared memory holding the message to pass to secure world
  * @offs:	offset of the message in @shm
+ * @system_thread: true if caller requests TEE system thread support
  *
  * Does a FF-A call to OP-TEE in secure world and handles eventual resulting
  * Remote Procedure Calls (RPC) from OP-TEE.
@@ -612,7 +614,8 @@ done:
  */
 
 static int optee_ffa_do_call_with_arg(struct tee_context *ctx,
-				      struct tee_shm *shm, u_int offs)
+				      struct tee_shm *shm, u_int offs,
+				      bool system_thread)
 {
 	struct ffa_send_direct_data data = {
 		.data0 = OPTEE_FFA_YIELDING_CALL_WITH_ARG,
@@ -642,7 +645,7 @@ static int optee_ffa_do_call_with_arg(struct tee_context *ctx,
 	if (IS_ERR(rpc_arg))
 		return PTR_ERR(rpc_arg);
 
-	return optee_ffa_yielding_call(ctx, &data, rpc_arg);
+	return optee_ffa_yielding_call(ctx, &data, rpc_arg, system_thread);
 }
 
 /*
@@ -850,8 +853,7 @@ static int optee_ffa_probe(struct ffa_device *ffa_dev)
 	if (rc)
 		goto err_unreg_supp_teedev;
 	mutex_init(&optee->ffa.mutex);
-	mutex_init(&optee->call_queue.mutex);
-	INIT_LIST_HEAD(&optee->call_queue.waiters);
+	optee_cq_init(&optee->call_queue, 0);
 	optee_supp_init(&optee->supp);
 	optee_shm_arg_cache_init(optee, arg_cache_flags);
 	ffa_dev_set_drvdata(ffa_dev, optee);
diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
index 6bb5cae09688..7832ccefe6d0 100644
--- a/drivers/tee/optee/optee_private.h
+++ b/drivers/tee/optee/optee_private.h
@@ -40,15 +40,33 @@ typedef void (optee_invoke_fn)(unsigned long, unsigned long, unsigned long,
 				unsigned long, unsigned long,
 				struct arm_smccc_res *);
 
+/*
+ * struct optee_call_waiter - TEE entry may need to wait for a free TEE thread
+ * @list_node		Reference in waiters list
+ * @c			Waiting completion reference
+ * @sys_thread		True if waiter belongs to a system thread
+ */
 struct optee_call_waiter {
 	struct list_head list_node;
 	struct completion c;
+	bool sys_thread;
 };
 
+/*
+ * struct optee_call_queue - OP-TEE call queue management
+ * @mutex			Serializes access to this struct
+ * @waiters			List of threads waiting to enter OP-TEE
+ * @total_thread_count		Overall number of thread context in OP-TEE or 0
+ * @free_thread_count		Number of threads context free in OP-TEE
+ * @sys_thread_req_count	Number of registered system thread sessions
+ */
 struct optee_call_queue {
 	/* Serializes access to this struct */
 	struct mutex mutex;
 	struct list_head waiters;
+	int total_thread_count;
+	int free_thread_count;
+	int sys_thread_req_count;
 };
 
 struct optee_notif {
@@ -154,7 +172,8 @@ struct optee;
  */
 struct optee_ops {
 	int (*do_call_with_arg)(struct tee_context *ctx,
-				struct tee_shm *shm_arg, u_int offs);
+				struct tee_shm *shm_arg, u_int offs,
+				bool system_thread);
 	int (*to_msg_param)(struct optee *optee,
 			    struct optee_msg_param *msg_params,
 			    size_t num_params, const struct tee_param *params);
@@ -204,6 +223,7 @@ struct optee {
 struct optee_session {
 	struct list_head list_node;
 	u32 session_id;
+	bool use_sys_thread;
 };
 
 struct optee_context_data {
@@ -250,7 +270,9 @@ int optee_supp_send(struct tee_context *ctx, u32 ret, u32 num_params,
 int optee_open_session(struct tee_context *ctx,
 		       struct tee_ioctl_open_session_arg *arg,
 		       struct tee_param *param);
-int optee_close_session_helper(struct tee_context *ctx, u32 session);
+int optee_system_session(struct tee_context *ctx, u32 session);
+int optee_close_session_helper(struct tee_context *ctx, u32 session,
+			       bool system_thread);
 int optee_close_session(struct tee_context *ctx, u32 session);
 int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg,
 		      struct tee_param *param);
@@ -298,8 +320,9 @@ static inline void optee_to_msg_param_value(struct optee_msg_param *mp,
 	mp->u.value.c = p->u.value.c;
 }
 
+void optee_cq_init(struct optee_call_queue *cq, int thread_count);
 void optee_cq_wait_init(struct optee_call_queue *cq,
-			struct optee_call_waiter *w);
+			struct optee_call_waiter *w, bool sys_thread);
 void optee_cq_wait_for_completion(struct optee_call_queue *cq,
 				  struct optee_call_waiter *w);
 void optee_cq_wait_final(struct optee_call_queue *cq,
diff --git a/drivers/tee/optee/smc_abi.c b/drivers/tee/optee/smc_abi.c
index d5b28fd35d66..3b60acc15cf0 100644
--- a/drivers/tee/optee/smc_abi.c
+++ b/drivers/tee/optee/smc_abi.c
@@ -283,7 +283,7 @@ static void optee_enable_shm_cache(struct optee *optee)
 	struct optee_call_waiter w;
 
 	/* We need to retry until secure world isn't busy. */
-	optee_cq_wait_init(&optee->call_queue, &w);
+	optee_cq_wait_init(&optee->call_queue, &w, false);
 	while (true) {
 		struct arm_smccc_res res;
 
@@ -308,7 +308,7 @@ static void __optee_disable_shm_cache(struct optee *optee, bool is_mapped)
 	struct optee_call_waiter w;
 
 	/* We need to retry until secure world isn't busy. */
-	optee_cq_wait_init(&optee->call_queue, &w);
+	optee_cq_wait_init(&optee->call_queue, &w, false);
 	while (true) {
 		union {
 			struct arm_smccc_res smccc;
@@ -507,7 +507,7 @@ static int optee_shm_register(struct tee_context *ctx, struct tee_shm *shm,
 	msg_arg->params->u.tmem.buf_ptr = virt_to_phys(pages_list) |
 	  (tee_shm_get_page_offset(shm) & (OPTEE_MSG_NONCONTIG_PAGE_SIZE - 1));
 
-	if (optee->ops->do_call_with_arg(ctx, shm_arg, 0) ||
+	if (optee->ops->do_call_with_arg(ctx, shm_arg, 0, false) ||
 	    msg_arg->ret != TEEC_SUCCESS)
 		rc = -EINVAL;
 
@@ -550,7 +550,7 @@ static int optee_shm_unregister(struct tee_context *ctx, struct tee_shm *shm)
 	msg_arg->params[0].attr = OPTEE_MSG_ATTR_TYPE_RMEM_INPUT;
 	msg_arg->params[0].u.rmem.shm_ref = (unsigned long)shm;
 
-	if (optee->ops->do_call_with_arg(ctx, shm_arg, 0) ||
+	if (optee->ops->do_call_with_arg(ctx, shm_arg, 0, false) ||
 	    msg_arg->ret != TEEC_SUCCESS)
 		rc = -EINVAL;
 out:
@@ -878,6 +878,7 @@ static void optee_handle_rpc(struct tee_context *ctx,
  * @ctx:	calling context
  * @shm:	shared memory holding the message to pass to secure world
  * @offs:	offset of the message in @shm
+ * @system_thread: true if caller requests TEE system thread support
  *
  * Does and SMC to OP-TEE in secure world and handles eventual resulting
  * Remote Procedure Calls (RPC) from OP-TEE.
@@ -885,7 +886,8 @@ static void optee_handle_rpc(struct tee_context *ctx,
  * Returns return code from secure world, 0 is OK
  */
 static int optee_smc_do_call_with_arg(struct tee_context *ctx,
-				      struct tee_shm *shm, u_int offs)
+				      struct tee_shm *shm, u_int offs,
+				      bool system_thread)
 {
 	struct optee *optee = tee_get_drvdata(ctx->teedev);
 	struct optee_call_waiter w;
@@ -926,7 +928,7 @@ static int optee_smc_do_call_with_arg(struct tee_context *ctx,
 		reg_pair_from_64(&param.a1, &param.a2, parg);
 	}
 	/* Initialize waiter */
-	optee_cq_wait_init(&optee->call_queue, &w);
+	optee_cq_wait_init(&optee->call_queue, &w, system_thread);
 	while (true) {
 		struct arm_smccc_res res;
 
@@ -977,7 +979,7 @@ static int simple_call_with_arg(struct tee_context *ctx, u32 cmd)
 		return PTR_ERR(msg_arg);
 
 	msg_arg->cmd = cmd;
-	optee_smc_do_call_with_arg(ctx, shm, offs);
+	optee_smc_do_call_with_arg(ctx, shm, offs, false);
 
 	optee_free_msg_arg(ctx, entry, offs);
 	return 0;
@@ -1210,6 +1212,7 @@ static const struct tee_driver_ops optee_clnt_ops = {
 	.release = optee_release,
 	.open_session = optee_open_session,
 	.close_session = optee_close_session,
+	.system_session = optee_system_session,
 	.invoke_func = optee_invoke_func,
 	.cancel_req = optee_cancel_req,
 	.shm_register = optee_shm_register,
@@ -1357,6 +1360,16 @@ static bool optee_msg_exchange_capabilities(optee_invoke_fn *invoke_fn,
 	return true;
 }
 
+static unsigned int optee_msg_get_thread_count(optee_invoke_fn *invoke_fn)
+{
+	struct arm_smccc_res res;
+
+	invoke_fn(OPTEE_SMC_GET_THREAD_COUNT, 0, 0, 0, 0, 0, 0, 0, &res);
+	if (res.a0)
+		return 0;
+	return res.a1;
+}
+
 static struct tee_shm_pool *
 optee_config_shm_memremap(optee_invoke_fn *invoke_fn, void **memremaped_shm)
 {
@@ -1609,6 +1622,7 @@ static int optee_probe(struct platform_device *pdev)
 	struct optee *optee = NULL;
 	void *memremaped_shm = NULL;
 	unsigned int rpc_param_count;
+	unsigned int thread_count;
 	struct tee_device *teedev;
 	struct tee_context *ctx;
 	u32 max_notif_value;
@@ -1636,6 +1650,7 @@ static int optee_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	thread_count = optee_msg_get_thread_count(invoke_fn);
 	if (!optee_msg_exchange_capabilities(invoke_fn, &sec_caps,
 					     &max_notif_value,
 					     &rpc_param_count)) {
@@ -1725,8 +1740,7 @@ static int optee_probe(struct platform_device *pdev)
 	if (rc)
 		goto err_unreg_supp_teedev;
 
-	mutex_init(&optee->call_queue.mutex);
-	INIT_LIST_HEAD(&optee->call_queue.waiters);
+	optee_cq_init(&optee->call_queue, thread_count);
 	optee_supp_init(&optee->supp);
 	optee->smc.memremaped_shm = memremaped_shm;
 	optee->pool = pool;
diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 5ddfd5d9ac7f..792d6fae4354 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -1173,6 +1173,14 @@ int tee_client_close_session(struct tee_context *ctx, u32 session)
 }
 EXPORT_SYMBOL_GPL(tee_client_close_session);
 
+int tee_client_system_session(struct tee_context *ctx, u32 session)
+{
+	if (!ctx->teedev->desc->ops->system_session)
+		return -EINVAL;
+	return ctx->teedev->desc->ops->system_session(ctx, session);
+}
+EXPORT_SYMBOL_GPL(tee_client_system_session);
+
 int tee_client_invoke_func(struct tee_context *ctx,
 			   struct tee_ioctl_invoke_arg *arg,
 			   struct tee_param *param)
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index 17eb1c5205d3..911ddf92dcee 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -84,6 +84,7 @@ struct tee_param {
  * @release:		release this open file
  * @open_session:	open a new session
  * @close_session:	close a session
+ * @system_session:	declare session as a system session
  * @invoke_func:	invoke a trusted function
  * @cancel_req:		request cancel of an ongoing invoke or open
  * @supp_recv:		called for supplicant to get a command
@@ -100,6 +101,7 @@ struct tee_driver_ops {
 			    struct tee_ioctl_open_session_arg *arg,
 			    struct tee_param *param);
 	int (*close_session)(struct tee_context *ctx, u32 session);
+	int (*system_session)(struct tee_context *ctx, u32 session);
 	int (*invoke_func)(struct tee_context *ctx,
 			   struct tee_ioctl_invoke_arg *arg,
 			   struct tee_param *param);
@@ -430,6 +432,20 @@ int tee_client_open_session(struct tee_context *ctx,
 int tee_client_close_session(struct tee_context *ctx, u32 session);
 
 /**
+ * tee_client_system_session() - Declare session as a system session
+ * @ctx:	TEE Context
+ * @session:	Session id
+ *
+ * This function requests TEE to provision an entry context ready to use for
+ * that session only. The provisioned entry context is used for command
+ * invocation and session closure, not for command cancelling requests.
+ * TEE releases the provisioned context upon session closure.
+ *
+ * Return < 0 on error else 0 if an entry context has been provisioned.
+ */
+int tee_client_system_session(struct tee_context *ctx, u32 session);
+
+/**
  * tee_client_invoke_func() - Invoke a function in a Trusted Application
  * @ctx:	TEE Context
  * @arg:	Invoke arguments, see description of