tee: add supp_nowait flag in tee_context struct

This flag indicates that requests in this context should not wait for
tee-supplicant daemon to be started if not present and just return
with an error code. It is needed for requests which should be
non-blocking in nature like ones arising from TEE based kernel drivers
or any in kernel api that uses TEE internal client interface.
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

drivers/tee/optee/supp.c

@@ -88,10 +88,18 @@ u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params,
 {
 	struct optee *optee = tee_get_drvdata(ctx->teedev);
 	struct optee_supp *supp = &optee->supp;
-	struct optee_supp_req *req = kzalloc(sizeof(*req), GFP_KERNEL);
+	struct optee_supp_req *req;
 	bool interruptable;
 	u32 ret;
 
+	/*
+	 * Return in case there is no supplicant available and
+	 * non-blocking request.
+	 */
+	if (!supp->ctx && ctx->supp_nowait)
+		return TEEC_ERROR_COMMUNICATION;
+
+	req = kzalloc(sizeof(*req), GFP_KERNEL);
 	if (!req)
 		return TEEC_ERROR_OUT_OF_MEMORY;
 

drivers/tee/tee_core.c

@@ -106,6 +106,11 @@ static int tee_open(struct inode *inode, struct file *filp)
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);
 
+	/*
+	 * Default user-space behaviour is to wait for tee-supplicant
+	 * if not present for any requests in this context.
+	 */
+	ctx->supp_nowait = false;
 	filp->private_data = ctx;
 	return 0;
 }
@@ -982,6 +987,14 @@ tee_client_open_context(struct tee_context *start,
 	} while (IS_ERR(ctx) && PTR_ERR(ctx) != -ENOMEM);
 
 	put_device(put_dev);
+	/*
+	 * Default behaviour for in kernel client is to not wait for
+	 * tee-supplicant if not present for any requests in this context.
+	 * Also this flag could be configured again before call to
+	 * tee_client_open_session() if any in kernel client requires
+	 * different behaviour.
+	 */
+	ctx->supp_nowait = true;
 	return ctx;
 }
 EXPORT_SYMBOL_GPL(tee_client_open_context);

include/linux/tee_drv.h

@@ -47,6 +47,11 @@ struct tee_shm_pool;
  * @releasing:  flag that indicates if context is being released right now.
  *		It is needed to break circular dependency on context during
  *              shared memory release.
+ * @supp_nowait: flag that indicates that requests in this context should not
+ *              wait for tee-supplicant daemon to be started if not present
+ *              and just return with an error code. It is needed for requests
+ *              that arises from TEE based kernel drivers that should be
+ *              non-blocking in nature.
  */
 struct tee_context {
 	struct tee_device *teedev;
@@ -54,6 +59,7 @@ struct tee_context {
 	void *data;
 	struct kref refcount;
 	bool releasing;
+	bool supp_nowait;
 };
 
 struct tee_param_memref {