feat(sctlr2): add support for FEAT_SCTLR2

Arm v8.9 introduces FEAT_SCTLR2, adding SCTLR2_ELx registers.
Support this, context switching the registers and disabling
traps so lower ELs can access the new registers.

Change the FVP platform to default to handling this as a dynamic option
so the right decision can be made by the code at runtime.

Change-Id: I0c4cba86917b6b065a7e8dd6af7daf64ee18dcda
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/include/arch/aarch64/arch_features.h b/include/arch/aarch64/arch_features.h
index fcd0ee6..de21fea 100644
--- a/include/arch/aarch64/arch_features.h
+++ b/include/arch/aarch64/arch_features.h
@@ -136,6 +136,8 @@
  * +----------------------------+
  * |	FEAT_THE		|
  * +----------------------------+
+ * |	FEAT_SCTLR2		|
+ * +----------------------------+
  */
 
 __attribute__((always_inline))
@@ -268,6 +270,11 @@
 CREATE_FEATURE_FUNCS(feat_the, id_aa64pfr1_el1, ID_AA64PFR1_EL1_THE_SHIFT,
 		     ID_AA64PFR1_EL1_THE_MASK, THE_IMPLEMENTED, ENABLE_FEAT_THE)
 
+/* FEAT_SCTLR2 */
+CREATE_FEATURE_FUNCS(feat_sctlr2, id_aa64mmfr3_el1, ID_AA64MMFR3_EL1_SCTLR2_SHIFT,
+		     ID_AA64MMFR3_EL1_SCTLR2_MASK, SCTLR2_IMPLEMENTED,
+		     ENABLE_FEAT_SCTLR2)
+
 __attribute__((always_inline))
 static inline bool is_feat_sxpie_supported(void)
 {