fix(cpus): workaround for Cortex X3 erratum 2641945

Cortex X3 erratum 2641945 is a Cat B erratum that applies to all
revisions <= r1p0 and is fixed in r1p1.

The workaround is to disable the affected L1 data cache prefetcher
by setting CPUACTLR6_EL1[41] to 1. Doing so will incur a performance
penalty of ~1%. Contact Arm for an alternate workaround that impacts
power.

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

Change-Id: Ia6d6ac8a66936c63b8aa8d7698b937f42ba8f044
Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>

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

@@ -791,6 +791,10 @@ 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 still open.
 
+- ``ERRATA_X3_2641945``: This applies errata 2641945 workaround to Cortex-X3
+  CPU. This needs to be enabled only for revisions r0p0 and r1p0 of the CPU.
+  It is fixed in r1p1.
+
 - ``ERRATA_X3_2742421``: This applies errata 2742421 workaround to
   Cortex-X3 CPU. This needs to be enabled only for revisions r0p0, r1p0 and
   r1p1. It is fixed in r1p2.

include/lib/cpus/aarch64/cortex_x3.h

@@ -43,6 +43,11 @@
 #define CORTEX_X3_CPUACTLR5_EL1_BIT_55		(ULL(1) << 55)
 #define CORTEX_X3_CPUACTLR5_EL1_BIT_56		(ULL(1) << 56)
 
+/*******************************************************************************
+ * CPU Auxiliary Control register 6 specific definitions.
+ ******************************************************************************/
+#define CORTEX_X3_CPUACTLR6_EL1			S3_0_C15_C8_1
+
 /*******************************************************************************
  * CPU Extended Control register 2 specific definitions.
  ******************************************************************************/

lib/cpus/aarch64/cortex_x3.S

@@ -61,6 +61,12 @@ workaround_reset_end cortex_x3, ERRATUM(2615812)
 
 check_erratum_ls cortex_x3, ERRATUM(2615812), CPU_REV(1, 1)
 
+workaround_runtime_start cortex_x3, ERRATUM(2641945), ERRATA_X3_2641945
+	sysreg_bit_set	CORTEX_X3_CPUACTLR6_EL1, BIT(41)
+workaround_runtime_end cortex_x3, ERRATUM(2641945), NO_ISB
+
+check_erratum_ls cortex_x3, ERRATUM(2641945), CPU_REV(1, 0)
+
 workaround_reset_start cortex_x3, ERRATUM(2742421), ERRATA_X3_2742421
 	/* Set CPUACTLR5_EL1[56:55] to 2'b01 */
 	sysreg_bit_set CORTEX_X3_CPUACTLR5_EL1, CORTEX_X3_CPUACTLR5_EL1_BIT_55

lib/cpus/cpu-ops.mk

@@ -794,6 +794,10 @@ CPU_FLAG_LIST += ERRATA_X3_2313909
 # to revisions r0p0, r1p0, r1p1 of the Cortex-X3 cpu, it is still open.
 CPU_FLAG_LIST += ERRATA_X3_2615812
 
+# Flag to apply erratum 2641945 workaround on reset. This erratum applies
+# to revisions r0p0 and r1p0 of the Cortex-X3 cpu, it is fixed in r1p1.
+CPU_FLAG_LIST += ERRATA_X3_2641945
+
 # Flag to apply erratum 2742421 workaround on reset. This erratum applies
 # to revisions r0p0, r1p0 and r1p1 of the Cortex-X3 cpu, it is fixed in r1p2.
 CPU_FLAG_LIST += ERRATA_X3_2742421

services/std_svc/errata_abi/errata_abi_main.c

@@ -451,10 +451,11 @@ struct em_cpu_list cpu_list[] = {
 		[2] = {2302506, 0x00, 0x11, ERRATA_X3_2302506},
 		[3] = {2313909, 0x00, 0x10, ERRATA_X3_2313909},
 		[4] = {2615812, 0x00, 0x11, ERRATA_X3_2615812},
-		[5] = {2742421, 0x00, 0x11, ERRATA_X3_2742421},
-		[6] = {2743088, 0x00, 0x11, ERRATA_X3_2743088},
-		[7] = {2779509, 0x00, 0x11, ERRATA_X3_2779509},
-		[8 ... ERRATA_LIST_END] = UNDEF_ERRATA,
+		[5] = {2641945, 0x00, 0x10, ERRATA_X3_2641945},
+		[6] = {2742421, 0x00, 0x11, ERRATA_X3_2742421},
+		[7] = {2743088, 0x00, 0x11, ERRATA_X3_2743088},
+		[8] = {2779509, 0x00, 0x11, ERRATA_X3_2779509},
+		[9 ... ERRATA_LIST_END] = UNDEF_ERRATA,
 	}
 },
 #endif /* CORTEX_X3_H_INC */