Merge "feat(hcx): initialize HCRX_EL2 to its default value" into integration

1 files changed, 28 insertions, 1 deletions

diff --git a/lib/el3_runtime/aarch64/context_mgmt.c b/lib/el3_runtime/aarch64/context_mgmt.c
index 94d5ee1d2..c411b73ab 100644
--- a/lib/el3_runtime/aarch64/context_mgmt.c
+++ b/lib/el3_runtime/aarch64/context_mgmt.c
@@ -274,6 +274,19 @@ static void setup_ns_context(cpu_context_t *ctx, const struct entry_point_info *
 	u_register_t mdcr_el2 = ((read_pmcr_el0() >> PMCR_EL0_N_SHIFT) &
 			PMCR_EL0_N_MASK);
 	write_ctx_reg(get_el2_sysregs_ctx(ctx), CTX_MDCR_EL2, mdcr_el2);
+
+	if (is_feat_hcx_supported()) {
+		/*
+		 * Initialize register HCRX_EL2 with its init value.
+		 * As the value of HCRX_EL2 is UNKNOWN on reset, there is a
+		 * chance that this can lead to unexpected behavior in lower
+		 * ELs that have not been updated since the introduction of
+		 * this feature if not properly initialized, especially when
+		 * it comes to those bits that enable/disable traps.
+		 */
+		write_ctx_reg(get_el2_sysregs_ctx(ctx), CTX_HCRX_EL2,
+			HCRX_EL2_INIT_VAL);
+	}
 #endif /* CTX_INCLUDE_EL2_REGS */
 }
 
@@ -612,8 +625,22 @@ void cm_prepare_el3_exit(uint32_t security_state)
 	assert(ctx != NULL);
 
 	if (security_state == NON_SECURE) {
+		uint64_t el2_implemented = el_implemented(2);
+
 		scr_el3 = read_ctx_reg(get_el3state_ctx(ctx),
 						 CTX_SCR_EL3);
+
+		if (((scr_el3 & SCR_HCE_BIT) != 0U)
+			|| (el2_implemented != EL_IMPL_NONE)) {
+			/*
+			 * If context is not being used for EL2, initialize
+			 * HCRX_EL2 with its init value here.
+			 */
+			if (is_feat_hcx_supported()) {
+				write_hcrx_el2(HCRX_EL2_INIT_VAL);
+			}
+		}
+
 		if ((scr_el3 & SCR_HCE_BIT) != 0U) {
 			/* Use SCTLR_EL1.EE value to initialise sctlr_el2 */
 			sctlr_elx = read_ctx_reg(get_el1_sysregs_ctx(ctx),
@@ -629,7 +656,7 @@ void cm_prepare_el3_exit(uint32_t security_state)
 			sctlr_elx |= SCTLR_IESB_BIT;
 #endif
 			write_sctlr_el2(sctlr_elx);
-		} else if (el_implemented(2) != EL_IMPL_NONE) {
+		} else if (el2_implemented != EL_IMPL_NONE) {
 			el2_unused = true;
 
 			/*