[RFC] Another attempt at Provision TEE threads for system invocation

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;

drivers/tee/optee/call.c

@@ -39,9 +39,26 @@ 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->normal_waiters);
+	INIT_LIST_HEAD(&cq->sys_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_normal_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)
 {
+	bool need_wait = false;
+
 	/*
 	 * 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
@@ -53,15 +70,40 @@ void optee_cq_wait_init(struct optee_call_queue *cq,
 	mutex_lock(&cq->mutex);
 
 	/*
-	 * We add ourselves to the queue, but we don't wait. This
-	 * guarantees that we don't lose a completion if secure world
-	 * returns busy and another thread just exited and try to complete
-	 * someone.
+	 * We add ourselves to a queue, but we don't wait. This guarantees
+	 * that we don't lose a completion if secure world returns busy and
+	 * another thread just exited and try to complete someone.
 	 */
 	init_completion(&w->c);
-	list_add_tail(&w->list_node, &cq->waiters);
+	w->sys_thread = sys_thread;
+	if (sys_thread) {
+		list_add_tail(&w->list_node, &cq->sys_waiters);
+	} else {
+		list_add_tail(&w->list_node, &cq->normal_waiters);
+		if (cq->total_thread_count) {
+			/*
+			 * Claim a normal thread if one is available, else
+			 * we'll need to wait for a normal thread to be
+			 * released.
+			 */
+			if (cq->free_normal_thread_count > 0)
+				cq->free_normal_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 (cq->free_normal_thread_count > 0) {
+			cq->free_normal_thread_count--;
+			need_wait = false;
+		}
+		mutex_unlock(&cq->mutex);
+	}
 }
 
 void optee_cq_wait_for_completion(struct optee_call_queue *cq,
@@ -74,7 +116,10 @@ void optee_cq_wait_for_completion(struct optee_call_queue *cq,
 	/* Move to end of list to get out of the way for other waiters */
 	list_del(&w->list_node);
 	reinit_completion(&w->c);
-	list_add_tail(&w->list_node, &cq->waiters);
+	if (w->sys_thread)
+		list_add_tail(&w->list_node, &cq->sys_waiters);
+	else
+		list_add_tail(&w->list_node, &cq->normal_waiters);
 
 	mutex_unlock(&cq->mutex);
 }
@@ -83,10 +128,19 @@ static void optee_cq_complete_one(struct optee_call_queue *cq)
 {
 	struct optee_call_waiter *w;
 
-	list_for_each_entry(w, &cq->waiters, list_node) {
+	list_for_each_entry(w, &cq->sys_waiters, list_node) {
 		if (!completion_done(&w->c)) {
 			complete(&w->c);
-			break;
+			return;
+		}
+	}
+
+	if (!cq->total_thread_count || cq->free_normal_thread_count > 0) {
+		list_for_each_entry(w, &cq->normal_waiters, list_node) {
+			if (!completion_done(&w->c)) {
+				complete(&w->c);
+				break;
+			}
 		}
 	}
 }
@@ -104,6 +158,9 @@ void optee_cq_wait_final(struct optee_call_queue *cq,
 	/* Get out of the list */
 	list_del(&w->list_node);
 
+	if (!w->sys_thread)
+		cq->free_normal_thread_count++; /* Release a normal thread */
+
 	/* Wake up one eventual waiting task */
 	optee_cq_complete_one(cq);
 
@@ -119,6 +176,36 @@ void optee_cq_wait_final(struct optee_call_queue *cq,
 	mutex_unlock(&cq->mutex);
 }
 
+bool optee_cq_inc_sys_thread_count(struct optee_call_queue *cq)
+{
+	bool rc = false;
+
+	mutex_lock(&cq->mutex);
+
+	/* Leave at least 1 normal (non-system) thread */
+	if (cq->res_sys_thread_count + 1 < cq->total_thread_count) {
+		cq->free_normal_thread_count--;
+		cq->res_sys_thread_count++;
+		rc = true;
+	}
+
+	mutex_unlock(&cq->mutex);
+
+	return rc;
+}
+
+void optee_cq_dec_sys_thread_count(struct optee_call_queue *cq)
+{
+	mutex_lock(&cq->mutex);
+	if (cq->res_sys_thread_count > 0) {
+		cq->res_sys_thread_count--;
+		cq->free_normal_thread_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 +415,8 @@ 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 +448,29 @@ int optee_open_session(struct tee_context *ctx,
 	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_context_data *ctxdata = ctx->data;
+	struct optee *optee = tee_get_drvdata(ctx->teedev);
+	struct optee_session *sess;
+	int rc = -EINVAL;
+
+	mutex_lock(&ctxdata->mutex);
+
+	sess = find_session(ctxdata, session);
+	if (sess && !sess->use_sys_thread &&
+	    optee_cq_inc_sys_thread_count(&optee->call_queue)) {
+		rc = 0;
+		sess->use_sys_thread = true;
+	}
+
+	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;
@@ -374,8 +484,10 @@ 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);
 
+	if (system_thread)
+		optee_cq_dec_sys_thread_count(&optee->call_queue);
 	optee_free_msg_arg(ctx, entry, offs);
 
 	return 0;
@@ -385,6 +497,7 @@ 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 +507,10 @@ 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 +522,15 @@ 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 +549,7 @@ 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 +574,15 @@ 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 +594,7 @@ 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;

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);

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)
@@ -612,7 +613,8 @@ static int optee_ffa_yielding_call(struct tee_context *ctx,
  */
 
 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 +644,7 @@ 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 +852,7 @@ 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);