fix(cpus): workaround for Cortex-A715 erratum 3699560

Cortex-A715 erratum 3699560 that applies to all revisions <= r1p3
and 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-2148827/latest/

Change-Id: I183aa921b4b6f715d64eb6b70809de2566017d31
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>

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

@@ -960,6 +960,10 @@ For Cortex-A715, the following errata build flags are defined :
    Cortex-A715 CPU. This needs to be enabled for revisions r0p0, r1p0
    and r1p1. It is fixed in r1p2.
 
+-  ``ERRATA_A715_3699560``: This applies errata 3699560 workaround to
+   Cortex-A715 CPU. This needs to be enabled for revisions r0p0, r1p0,
+   r1p2, r1p3. It is still open.
+
 For Cortex-A720, the following errata build flags are defined :
 
 -  ``ERRATA_A720_2792132``: This applies errata 2792132 workaround to

include/lib/cpus/aarch64/cortex_a715.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
  */
@@ -38,4 +38,8 @@
 #define CORTEX_A715_CPUPWRCTLR_EL1				S3_0_C15_C2_7
 #define CORTEX_A715_CPUPWRCTLR_EL1_CORE_PWRDN_BIT		U(1)
 
+#ifndef __ASSEMBLER__
+long check_erratum_cortex_a715_3699560(long cpu_rev);
+#endif /* __ASSEMBLER__ */
+
 #endif /* CORTEX_A715_H */

lib/cpus/aarch64/cortex_a715.S

@@ -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
  */
@@ -22,6 +22,8 @@
 #error "Cortex-A715 supports only AArch64. Compile with CTX_INCLUDE_AARCH32_REGS=0"
 #endif
 
+.global check_erratum_cortex_a715_3699560
+
 #if WORKAROUND_CVE_2022_23960
 	wa_cve_2022_23960_bhb_vector_table CORTEX_A715_BHB_LOOP_COUNT, cortex_a715
 #endif /* WORKAROUND_CVE_2022_23960 */
@@ -127,6 +129,10 @@ workaround_reset_end cortex_a715, CVE(2022, 23960)
 
 check_erratum_chosen cortex_a715, CVE(2022, 23960), WORKAROUND_CVE_2022_23960
 
+add_erratum_entry cortex_a715, ERRATUM(3699560), ERRATA_A715_3699560, NO_APPLY_AT_RESET
+
+check_erratum_ls cortex_a715, ERRATUM(3699560), CPU_REV(1, 3)
+
 cpu_reset_func_start cortex_a715
 	/* Disable speculative loads */
 	msr	SSBS, xzr

lib/cpus/cpu-ops.mk

@@ -989,6 +989,11 @@ CPU_FLAG_LIST += ERRATA_A715_2561034
 # only to revision r0p0, r1p0 and r1p1. It is fixed in r1p2.
 CPU_FLAG_LIST += ERRATA_A715_2728106
 
+# Flag to apply erratum 3699560 workaround during context save/restore of
+# ICH_VMCR_EL2 reg. This erratum applies to revisions r0p0, r1p0, r1p2, r1p3
+# of the Cortex-A715 cpu and is still open.
+CPU_FLAG_LIST += ERRATA_A715_3699560
+
 # Flag to apply erratum 2792132 workaround during reset. This erratum applies
 # to revisions r0p0 and r0p1. It is fixed in r0p2.
 CPU_FLAG_LIST += ERRATA_A720_2792132

lib/cpus/errata_common.c

@@ -11,6 +11,7 @@
 #include <cortex_a75.h>
 #include <cortex_a520.h>
 #include <cortex_a710.h>
+#include <cortex_a715.h>
 #include <cortex_x4.h>
 #include <lib/cpus/cpu_ops.h>
 #include <lib/cpus/errata.h>
@@ -52,6 +53,13 @@ bool errata_ich_vmcr_el2_applies(void)
 		break;
 #endif /* ERRATA_A710_3701772 */
 
+#if ERRATA_A715_3699560
+	case EXTRACT_PARTNUM(CORTEX_A715_MIDR):
+		if (check_erratum_cortex_a715_3699560(cpu_get_rev_var()) == ERRATA_APPLIES)
+			return true;
+		break;
+#endif /* ERRATA_A715_3699560 */
+
 	default:
 		break;
 	}