diff --git a/services/spd/trusty/smcall.h b/services/spd/trusty/smcall.h
index 9c1c38c..c66f7db 100644
--- a/services/spd/trusty/smcall.h
+++ b/services/spd/trusty/smcall.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2020, NVIDIA Corporation. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -71,4 +72,11 @@
 #define SMC_YC_VDEV_KICK_VQ	  SMC_YIELDCALL_NR(SMC_ENTITY_TRUSTED_OS, 24U)
 #define SMC_YC_SET_ROT_PARAMS	  SMC_YIELDCALL_NR(SMC_ENTITY_TRUSTED_OS, 65535U)
 
+/*
+ * Standard Trusted OS Function IDs that fall under Trusted OS call range
+ * according to SMC calling convention
+ */
+#define SMC_FC64_GET_UUID		SMC_FASTCALL64_NR(63U, 0xFF01U) /* Implementation UID */
+#define SMC_FC_GET_UUID			SMC_FASTCALL_NR(63U, 0xFF01U) /* Implementation.UID */
+
 #endif /* SMCALL_H */
diff --git a/services/spd/trusty/trusty.c b/services/spd/trusty/trusty.c
index b10da76..e102b82 100644
--- a/services/spd/trusty/trusty.c
+++ b/services/spd/trusty/trusty.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2020, NVIDIA Corporation. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -16,11 +17,18 @@
 #include <common/debug.h>
 #include <common/runtime_svc.h>
 #include <lib/el3_runtime/context_mgmt.h>
+#include <lib/smccc.h>
 #include <plat/common/platform.h>
+#include <tools_share/uuid.h>
 
 #include "sm_err.h"
 #include "smcall.h"
 
+/* Trusty UID: RFC-4122 compliant UUID version 4 */
+DEFINE_SVC_UUID2(trusty_uuid,
+		 0x40ee25f0, 0xa2bc, 0x304c, 0x8c, 0x4c,
+		 0xa1, 0x73, 0xc5, 0x7d, 0x8a, 0xf1);
+
 /* macro to check if Hypervisor is enabled in the HCR_EL2 register */
 #define HYP_ENABLE_FLAG		0x286001U
 
@@ -256,6 +264,11 @@
 		SMC_RET1(handle, SMC_UNK);
 	} else {
 		switch (smc_fid) {
+		case SMC_FC64_GET_UUID:
+		case SMC_FC_GET_UUID:
+			/* provide the UUID for the service to the client */
+			SMC_UUID_RET(handle, trusty_uuid);
+			break;
 		case SMC_FC64_SET_FIQ_HANDLER:
 			return trusty_set_fiq_handler(handle, x1, x2, x3);
 		case SMC_FC64_GET_FIQ_REGS:
@@ -263,6 +276,12 @@
 		case SMC_FC_FIQ_EXIT:
 			return trusty_fiq_exit(handle, x1, x2, x3);
 		default:
+			/* Not all OENs greater than SMC_ENTITY_SECURE_MONITOR are supported */
+			if (SMC_ENTITY(smc_fid) > SMC_ENTITY_SECURE_MONITOR) {
+				VERBOSE("%s: unsupported SMC FID (0x%x)\n", __func__, smc_fid);
+				SMC_RET1(handle, SMC_UNK);
+			}
+
 			if (is_hypervisor_mode())
 				vmid = SMC_GET_GP(handle, CTX_GPREG_X7);
 
@@ -502,7 +521,7 @@
 	trusty_fast,
 
 	OEN_TOS_START,
-	SMC_ENTITY_SECURE_MONITOR,
+	OEN_TOS_END,
 	SMC_TYPE_FAST,
 	trusty_setup,
 	trusty_smc_handler