fix(bl31): allow use of EHF with S-EL2 SPMC
Currently, when SPMC at S-EL2 is used, we cannot use the RAS framework
to handle Group 0 interrupts. This is required on platforms where first
level of triaging needs to occur at EL3, before forwarding RAS handling
to a secure partition running atop an SPMC (hafnium).
The RAS framework depends on EHF and EHF registers for Group 0
interrupts to be trapped to EL3 when execution is both in secure world
and normal world. However, an FF-A compliant SPMC requires secure
interrupts to be trapped by the SPMC when execution is in S-EL0/S-EL1.
Consequently, the SPMC (hafnium) is incompatible with EHF, since it is
not re-entrant, and a Group 0 interrupt trapped to EL3 when execution is
in secure world, cannot be forwarded to an SP running atop SPMC.
This patch changes EHF to only register for Group 0 interrupts to be
trapped to EL3 when execution is in normal world and also makes it a
valid routing model to do so, when EL3_EXCEPTION_HANDLING is set (when
enabling the RAS framework).
Signed-off-by: Raghu Krishnamurthy <raghu.ncstate@gmail.com>
Change-Id: I72d4cf4d8ecc549a832d1c36055fbe95866747fe
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index dc18941..7232217 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -461,8 +461,11 @@
- ``EL3_EXCEPTION_HANDLING``: When set to ``1``, enable handling of exceptions
targeted at EL3. When set ``0`` (default), no exceptions are expected or
- handled at EL3, and a panic will result. This is supported only for AArch64
- builds.
+ handled at EL3, and a panic will result. The exception to this rule is when
+ ``SPMD_SPM_AT_SEL2`` is set to ``1``, in which case, only exceptions
+ occuring during normal world execution, are trapped to EL3. Any exception
+ trapped during secure world execution are trapped to the SPMC. This is
+ supported only for AArch64 builds.
- ``EVENT_LOG_LEVEL``: Chooses the log level to use for Measured Boot when
``MEASURED_BOOT`` is enabled. For a list of valid values, see ``LOG_LEVEL``.