feat(el3-spmc): add a flag to enable support to load SEL0 SP

Introduce a build flag for enabling the support for loading SEL0 SP in
EL3 SPMC.

Signed-off-by: Nishant Sharma <nishant.sharma@arm.com>
Change-Id: I1d63ae4d0d8374a732113565be90d58861506e39

Makefile

@@ -599,6 +599,12 @@ ifneq (${SPD},none)
 		ifneq ($(SP_LAYOUT_FILE),)
 		BL2_ENABLE_SP_LOAD := 1
 		endif
+
+		ifeq ($(SPMC_AT_EL3_SEL0_SP),1)
+			ifneq ($(SPMC_AT_EL3),1)
+			$(error SEL0 SP cannot be enabled without SPMC at EL3)
+			endif
+		endif
 	else
 		# All other SPDs in spd directory
 		SPD_DIR := spd
@@ -1191,6 +1197,7 @@ $(eval $(call assert_booleans,\
 	SPIN_ON_BL1_EXIT \
 	SPM_MM \
 	SPMC_AT_EL3 \
+	SPMC_AT_EL3_SEL0_SP \
 	SPMD_SPM_AT_SEL2 \
 	ENABLE_SPMD_LP \
 	TRANSFER_LIST \
@@ -1355,6 +1362,7 @@ $(eval $(call add_defines,\
 	SPIN_ON_BL1_EXIT \
 	SPM_MM \
 	SPMC_AT_EL3 \
+	SPMC_AT_EL3_SEL0_SP \
 	SPMD_SPM_AT_SEL2 \
 	TRANSFER_LIST \
 	TRUSTED_BOARD_BOOT \

docs/components/secure-partition-manager.rst

@@ -152,6 +152,8 @@ SPMC located at S-EL1, S-EL2 or EL3:
   exception level is set to S-EL1.
   ``SPMD_SPM_AT_SEL2`` is enabled. The context save/restore routine
   and exhaustive list of registers is visible at `[4]`_.
+- **SPMC_AT_EL3_SEL0_SP**: this option enables the support to load SEL0 SP
+  when SPMC at EL3 support is enabled.
 - **SP_LAYOUT_FILE**: this option specifies a text description file
   providing paths to SP binary images and manifests in DTS format
   (see `Describing secure partitions`_). It
@@ -257,6 +259,22 @@ Sample TF-A build command line when the SPMC is located at EL3:
     PLAT=fvp \
     all fip
 
+Sample TF-A build command line when the SPMC is located at EL3 and SEL0 SP is
+enabled:
+
+.. code:: shell
+
+    make \
+    CROSS_COMPILE=aarch64-none-elf- \
+    SPD=spmd \
+    SPMD_SPM_AT_SEL2=0 \
+    SPMC_AT_EL3=1 \
+    SPMC_AT_EL3_SEL0_SP=1 \
+    BL32=<path-to-tee-binary> \
+    BL33=<path-to-bl33-binary> \
+    PLAT=fvp \
+    all fip
+
 FVP model invocation
 ====================
 

docs/getting_started/build-options.rst

@@ -900,6 +900,10 @@ Common build options
    disabled). This configuration supports pre-Armv8.4 platforms (aka not
    implementing the ``FEAT_SEL2`` extension). This is an experimental feature.
 
+-  ``SPMC_AT_EL3_SEL0_SP`` : Boolean option to enable SEL0 SP load support when
+   ``SPMC_AT_EL3`` is enabled. The default value if ``0`` (disabled). This
+   option cannot be enabled (``1``) when (``SPMC_AT_EL3``) is disabled.
+
 -  ``SPMC_OPTEE`` : This boolean option is used jointly with the SPM
    Dispatcher option (``SPD=spmd``) and with ``SPMD_SPM_AT_SEL2=0`` to
    indicate that the SPMC at S-EL1 is OP-TEE and an OP-TEE specific loading

make_helpers/defaults.mk

@@ -240,6 +240,9 @@ SPM_MM				:= 0
 # Use the FF-A SPMC implementation in EL3.
 SPMC_AT_EL3			:= 0
 
+# Enable SEL0 SP when SPMC is enabled at EL3
+SPMC_AT_EL3_SEL0_SP		:=0
+
 # Use SPM at S-EL2 as a default config for SPMD
 SPMD_SPM_AT_SEL2		:= 1