[PATCH RFC 3/5] optee: riscv: enable persistent shared argument cache

[Amirreza Zarrabi]

Use the OP-TEE shared argument cache when secure world advertises
OPTEE_ABI_SEC_CAP_ARG_OFFSET.

In this mode the argument structure can reside at an offset within an
already registered parcel-backed shared-memory buffer, allowing the same
buffer to be reused across calls instead of creating and reclaiming a
parcel for each call.

Signed-off-by: Amirreza Zarrabi <amirreza.zarrabi@xxxxxxxxxxxxxxxx>
---
 drivers/tee/optee/optee_riscv.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/tee/optee/optee_riscv.c b/drivers/tee/optee/optee_riscv.c
index 36115326486d..72c9eb85f4fe 100644
--- a/drivers/tee/optee/optee_riscv.c
+++ b/drivers/tee/optee/optee_riscv.c
@@ -1149,6 +1149,7 @@ static int optee_riscv_probe(struct platform_device *pdev)
 	struct tee_device *teedev;
 	struct tee_context *ctx;
 	struct mbox_client *client;
+	u32 arg_cache_flags = 0;
 	struct optee *optee;
 	u32 sec_caps;
 	unsigned int nr_cpus;
@@ -1219,6 +1220,15 @@ static int optee_riscv_probe(struct platform_device *pdev)
 		goto err_free_channels;
 	}
 
+	/*
+	 * If OP-TEE can read the argument struct from an offset into a shared
+	 * memory buffer, cache and reuse one buffer across calls instead of
+	 * creating a fresh parcel per call. This is the persistent pool that
+	 * matches the FF-A OPTEE_FFA_SEC_CAP_ARG_OFFSET path.
+	 */
+	if (sec_caps & OPTEE_ABI_SEC_CAP_ARG_OFFSET)
+		arg_cache_flags |= OPTEE_SHM_ARG_SHARED;
+
 	pool = optee_riscv_shm_pool_alloc_pages();
 	if (IS_ERR(pool)) {
 		rc = PTR_ERR(pool);
@@ -1266,7 +1276,7 @@ static int optee_riscv_probe(struct platform_device *pdev)
 	atomic_set(&optee->riscv.next_nonce, 0);
 	optee_cq_init(&optee->call_queue, 0);
 	optee_supp_init(&optee->supp);
-	optee_shm_arg_cache_init(optee, 0);
+	optee_shm_arg_cache_init(optee, arg_cache_flags);
 	mutex_init(&optee->rpmb_dev_mutex);
 	platform_set_drvdata(pdev, optee);
 

-- 
2.34.1