fix(ras): trap "RAS error record" accesses only for NS

RAS_TRAP_LOWER_EL_ERR_ACCESS was used to prevent access to RAS error
record registers (RAS ERR* & RAS ERX*) from lower EL's in any security
state. To give more fine grain control per world basis re-purpose this
macro to RAS_TRAP_NS_ERR_REC_ACCESS, which will enable the trap only
if Error record registers are accessed from NS.
This will also help in future scenarios when RAS handling(in Firmware
first handling paradigm)can be offloaded to a secure partition.

This is first patch in series to refactor RAS framework in TF-A.

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: Ifa7f60bc8c82c9960adf029001bc36c443016d5d

Makefile

@@ -1051,7 +1051,7 @@ $(eval $(call assert_booleans,\
         ENCRYPT_BL31 \
         ENCRYPT_BL32 \
         ERRATA_SPECULATIVE_AT \
-        RAS_TRAP_LOWER_EL_ERR_ACCESS \
+        RAS_TRAP_NS_ERR_REC_ACCESS \
         COT_DESC_IN_DTB \
         USE_SP804_TIMER \
         PSA_FWU_SUPPORT \
@@ -1191,7 +1191,7 @@ $(eval $(call add_defines,\
         BL2_INV_DCACHE \
         USE_SPINLOCK_CAS \
         ERRATA_SPECULATIVE_AT \
-        RAS_TRAP_LOWER_EL_ERR_ACCESS \
+        RAS_TRAP_NS_ERR_REC_ACCESS \
         COT_DESC_IN_DTB \
         USE_SP804_TIMER \
         ENABLE_FEAT_RNG \

docs/components/ras.rst

@@ -30,8 +30,8 @@ introduced by the RAS extensions.
 
 The build option ``RAS_EXTENSION`` when set to ``1`` includes the RAS in run
 time firmware; ``EL3_EXCEPTION_HANDLING`` and ``HANDLE_EA_EL3_FIRST`` must also
-be set ``1``. ``RAS_TRAP_LOWER_EL_ERR_ACCESS`` controls the access to the RAS
-error record registers from lower ELs.
+be set ``1``. ``RAS_TRAP_NS_ERR_REC_ACCESS`` controls the access to the RAS
+error record registers from Non-secure.
 
 .. _ras-figure:
 

docs/getting_started/build-options.rst

@@ -987,7 +987,7 @@ Common build options
       implement this workaround due to the behaviour of the errata mentioned
       in new SDEN document which will get published soon.
 
-- ``RAS_TRAP_LOWER_EL_ERR_ACCESS``: This flag enables/disables the SCR_EL3.TERR
+- ``RAS_TRAP_NS_ERR_REC_ACCESS``: This flag enables/disables the SCR_EL3.TERR
   bit, to trap access to the RAS ERR and RAS ERX registers from lower ELs.
   This flag is disabled by default.
 

lib/el3_runtime/aarch64/context_mgmt.c

@@ -206,6 +206,17 @@ static void setup_ns_context(cpu_context_t *ctx, const struct entry_point_info *
 	/* Allow access to Allocation Tags when MTE is implemented. */
 	scr_el3 |= SCR_ATA_BIT;
 
+#if RAS_TRAP_NS_ERR_REC_ACCESS
+	/*
+	 * SCR_EL3.TERR: Trap Error record accesses. Accesses to the RAS ERR
+	 * and RAS ERX registers from EL1 and EL2(from any security state)
+	 * are trapped to EL3.
+	 * Set here to trap only for NS EL1/EL2
+	 *
+	 */
+	scr_el3 |= SCR_TERR_BIT;
+#endif
+
 #ifdef IMAGE_BL31
 	/*
 	 * SCR_EL3.IRQ, SCR_EL3.FIQ: Enable the physical FIQ and IRQ routing as
@@ -306,14 +317,6 @@ static void setup_context_common(cpu_context_t *ctx, const entry_point_info_t *e
 	scr_el3 |= SCR_TRNDR_BIT;
 #endif
 
-#if RAS_TRAP_LOWER_EL_ERR_ACCESS
-	/*
-	 * SCR_EL3.TERR: Trap Error record accesses. Accesses to the RAS ERR
-	 * and RAS ERX registers from EL1 and EL2 are trapped to EL3.
-	 */
-	scr_el3 |= SCR_TERR_BIT;
-#endif
-
 #if !HANDLE_EA_EL3_FIRST
 	/*
 	 * SCR_EL3.EA: Do not route External Abort and SError Interrupt External

make_helpers/defaults.mk

@@ -413,8 +413,8 @@ SUPPORT_STACK_MEMTAG		:= no
 # Select workaround for AT speculative behaviour.
 ERRATA_SPECULATIVE_AT		:= 0
 
-# Trap RAS error record access from lower EL
-RAS_TRAP_LOWER_EL_ERR_ACCESS	:= 0
+# Trap RAS error record access from Non secure
+RAS_TRAP_NS_ERR_REC_ACCESS	:= 0
 
 # Build option to create cot descriptors using fconf
 COT_DESC_IN_DTB			:= 0