fix(cpus): workaround for Cortex-X3 erratum 3701769

Cortex-X3 erratum 3701769 that applies to r0p0, r1p0, r1p1 and r1p2
is still Open.

The workaround is for EL3 software that performs context save/restore
on a change of Security state to use a value of SCR_EL3.NS when
accessing ICH_VMCR_EL2 that reflects the Security state that owns the
data being saved or restored.

SDEN documentation:
https://developer.arm.com/documentation/SDEN-2055130/latest/

Change-Id: Ifd722e1bb8616ada2ad158297a7ca80b19a3370b
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>

docs/design/cpu-specific-build-macros.rst

@@ -833,6 +833,10 @@ For Cortex-X3, the following errata build flags are defined :
   CPU. This needs to be enabled only for revisions r0p0, r1p0 and r1p1 of the
   CPU. It is fixed in r1p2.
 
+- ``ERRATA_X3_3701769``: This applies errata 3701769 workaround to Cortex-X3
+  CPU. This needs to be enabled only for revisions r0p0, r1p0, r1p1 and r1p2
+  of the CPU and it is still open.
+
 For Cortex-X4, the following errata build flags are defined :
 
 - ``ERRATA_X4_2701112``: This applies erratum 2701112 workaround to Cortex-X4

include/lib/cpus/aarch64/cortex_x3.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021-2024, Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2025, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -63,4 +63,8 @@
 #define CORTEX_X3_CPUACTLR3_EL1			S3_0_C15_C1_2
 #define CORTEX_X3_CPUACTLR3_EL1_BIT_47		(ULL(1) << 47)
 
+#ifndef __ASSEMBLER__
+long check_erratum_cortex_x3_3701769(long cpu_rev);
+#endif /* __ASSEMBLER__ */
+
 #endif /* CORTEX_X3_H */

lib/cpus/aarch64/cortex_x3.S

@@ -22,6 +22,12 @@
 #error "Cortex-X3 supports only AArch64. Compile with CTX_INCLUDE_AARCH32_REGS=0"
 #endif
 
+.global check_erratum_cortex_x3_3701769
+
+add_erratum_entry cortex_x3, ERRATUM(3701769), ERRATA_X3_3701769, NO_APPLY_AT_RESET
+
+check_erratum_ls cortex_x3, ERRATUM(3701769), CPU_REV(1, 2)
+
 #if WORKAROUND_CVE_2022_23960
 	wa_cve_2022_23960_bhb_vector_table CORTEX_X3_BHB_LOOP_COUNT, cortex_x3
 #endif /* WORKAROUND_CVE_2022_23960 */

lib/cpus/cpu-ops.mk

@@ -832,6 +832,11 @@ CPU_FLAG_LIST += ERRATA_X3_2742421
 # to revisions r0p0, r1p0 and r1p1 of the Cortex-X3 cpu, it is fixed in r1p2.
 CPU_FLAG_LIST += ERRATA_X3_2743088
 
+# Flag to apply erratum 3701769 workaround during context save/restore of
+# ICH_VMCR_EL2 reg. This erratum applies to revisions r0p0, r1p0, r1p1 and r1p2
+# of the Cortex-X3 cpu and is still open.
+CPU_FLAG_LIST += ERRATA_X3_3701769
+
 # Flag to apply erratum 2779509 workaround on reset. This erratum applies
 # to revisions r0p0, r1p0, r1p1 of the Cortex-X3 cpu, it is fixed in r1p2.
 CPU_FLAG_LIST += ERRATA_X3_2779509

lib/cpus/errata_common.c

@@ -16,6 +16,7 @@
 #include <cortex_a720_ae.h>
 #include <cortex_a725.h>
 #include <cortex_x2.h>
+#include <cortex_x3.h>
 #include <cortex_x4.h>
 #include <lib/cpus/cpu_ops.h>
 #include <lib/cpus/errata.h>
@@ -92,6 +93,13 @@ bool errata_ich_vmcr_el2_applies(void)
 		break;
 #endif /* ERRATA_X2_3701772 */
 
+#if ERRATA_X3_3701769
+	case EXTRACT_PARTNUM(CORTEX_X3_MIDR):
+		if (check_erratum_cortex_x3_3701769(cpu_get_rev_var()) == ERRATA_APPLIES)
+			return true;
+		break;
+#endif /* ERRATA_X3_3701769 */
+
 	default:
 		break;
 	}