docs(spm): support for handling Group0 interrupts

Please refer the doc update.

Change-Id: Ib79fae1296bc28fa9bd0cd79609d6153bb57519b
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>

docs/components/secure-partition-manager.rst

@@ -1318,6 +1318,25 @@ A brief description of the events:
        direct request to SP2 by invoking FFA_RUN.
   - 9) SPMC resumes the pre-empted vCPU of SP2.
 
+EL3 interrupt handling
+~~~~~~~~~~~~~~~~~~~~~~
+
+In GICv3 based systems, EL3 interrupts are configured as Group0 secure
+interrupts. Execution traps to SPMC when a Group0 interrupt triggers while an
+SP is running. Further, SPMC running at S-EL2 uses FFA_EL3_INTR_HANDLE ABI to
+request EL3 platform firmware to handle a pending Group0 interrupt.
+Similarly, SPMD registers a handler with interrupt management framework to
+delegate handling of Group0 interrupt to the platform if the interrupt triggers
+in normal world.
+
+ - Platform hook
+
+   - plat_spmd_handle_group0_interrupt
+
+     SPMD provides platform hook to handle Group0 secure interrupts. In the
+     current design, SPMD expects the platform not to delegate handling to the
+     NWd (such as through SDEI) while processing Group0 interrupts.
+
 Power management
 ----------------
 
@@ -1557,4 +1576,4 @@ Client <https://developer.arm.com/documentation/den0006/d/>`__
 
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-*Copyright (c) 2020-2022, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2020-2023, Arm Limited and Contributors. All rights reserved.*