[PATCH v2 2/6] arm64: initialise SCTLR2_ELx register at boot time
From: Yeoreum Yun
Date: Mon Aug 11 2025 - 12:37:41 EST
add initialisation for SCTRL2_ELx register at boot time.
Signed-off-by: Yeoreum Yun <yeoreum.yun@xxxxxxx>
---
arch/arm64/include/asm/el2_setup.h | 6 ++++++
arch/arm64/include/asm/sysreg.h | 22 ++++++++++++++++++++++
arch/arm64/kernel/head.S | 5 ++++-
3 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
index d755b4d46d77..347ac4cc1283 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -48,6 +48,11 @@
isb
.endm
+.macro __init_el2_sctlr2
+ init_sctlr2_elx 2, x0
+ isb
+.endm
+
.macro __init_el2_hcrx
mrs x0, id_aa64mmfr1_el1
ubfx x0, x0, #ID_AA64MMFR1_EL1_HCX_SHIFT, #4
@@ -411,6 +416,7 @@
*/
.macro init_el2_state
__init_el2_sctlr
+ __init_el2_sctlr2
__init_el2_hcrx
__init_el2_timers
__init_el2_debug
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index d5b5f2ae1afa..8b82af5be199 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -868,6 +868,8 @@
#define INIT_SCTLR_EL2_MMU_OFF \
(SCTLR_EL2_RES1 | ENDIAN_SET_EL2)
+#define INIT_SCTLR2_EL2 UL(0)
+
/* SCTLR_EL1 specific flags. */
#ifdef CONFIG_CPU_BIG_ENDIAN
#define ENDIAN_SET_EL1 (SCTLR_EL1_E0E | SCTLR_ELx_EE)
@@ -888,6 +890,8 @@
SCTLR_EL1_LSMAOE | SCTLR_EL1_nTLSMD | SCTLR_EL1_EIS | \
SCTLR_EL1_TSCXT | SCTLR_EL1_EOS)
+#define INIT_SCTLR2_EL1 UL(0)
+
/* MAIR_ELx memory attributes (used by Linux) */
#define MAIR_ATTR_DEVICE_nGnRnE UL(0x00)
#define MAIR_ATTR_DEVICE_nGnRE UL(0x04)
@@ -1164,6 +1168,24 @@
msr hcr_el2, \reg
#endif
.endm
+
+ .macro init_sctlr2_elx, el, tmp
+ mrs_s \tmp, SYS_ID_AA64MMFR3_EL1
+ ubfx \tmp, \tmp, #ID_AA64MMFR3_EL1_SCTLRX_SHIFT, #4
+ cbz \tmp, .Lskip_sctlr2_\@
+ .if \el == 2
+ mov_q \tmp, INIT_SCTLR2_EL2
+ msr_s SYS_SCTLR_EL2, \tmp
+ .else
+ mov_q \tmp, INIT_SCTLR2_EL1
+ .if \el == 12
+ msr_s SYS_SCTLR_EL12, \tmp
+ .else
+ msr_s SYS_SCTLR_EL1, \tmp
+ .endif
+ .endif
+.Lskip_sctlr2_\@:
+ .endm
#else
#include <linux/bitfield.h>
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index ca04b338cb0d..0dff7593e50b 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -276,6 +276,7 @@ SYM_INNER_LABEL(init_el1, SYM_L_LOCAL)
mov_q x0, INIT_SCTLR_EL1_MMU_OFF
pre_disable_mmu_workaround
msr sctlr_el1, x0
+ init_sctlr2_elx 1, x0
isb
mov_q x0, INIT_PSTATE_EL1
msr spsr_el1, x0
@@ -298,7 +299,6 @@ SYM_INNER_LABEL(init_el2, SYM_L_LOCAL)
msr sctlr_el2, x0
isb
0:
-
init_el2_hcr HCR_HOST_NVHE_FLAGS
init_el2_state
@@ -315,12 +315,15 @@ SYM_INNER_LABEL(init_el2, SYM_L_LOCAL)
/* Set a sane SCTLR_EL1, the VHE way */
msr_s SYS_SCTLR_EL12, x1
+ init_sctlr2_elx 12, x2
mov x2, #BOOT_CPU_FLAG_E2H
b 3f
2:
msr sctlr_el1, x1
+ init_sctlr2_elx 1, x2
mov x2, xzr
+
3:
mov x0, #INIT_PSTATE_EL1
msr spsr_el2, x0
--
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}