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>

2 files changed, 22 insertions, 1 deletions

diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c
index 43626e15703a..92f56b8645e3 100644
--- a/drivers/tee/optee/supp.c
+++ b/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;
 
diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 7b2bb4c50058..adf2588282fc 100644
--- a/drivers/tee/tee_core.c
+++ b/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);