linux-kernel - [PATCH v4 4/5] arm64: initialise SCTLR2_EL1 at cpu_soft

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Message-Id: <20250821172408.2101870-5-yeoreum.yun@arm.com>
Date: Thu, 21 Aug 2025 18:24:07 +0100
From: Yeoreum Yun <yeoreum.yun@....com>
To: catalin.marinas@....com,
	will@...nel.org,
	broonie@...nel.org,
	oliver.upton@...ux.dev,
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Cc: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	kvmarm@...ts.linux.dev,
	Yeoreum Yun <yeoreum.yun@....com>
Subject: [PATCH v4 4/5] arm64: initialise SCTLR2_EL1 at cpu_soft_restart()

Explicitly initialize the SCTLR2_ELx register before launching
a new kernel via kexec() to avoid leaving SCTLR2_ELx with an
arbitrary value when the new kernel runs.

Signed-off-by: Yeoreum Yun <yeoreum.yun@....com>
---
 arch/arm64/kernel/cpu-reset.S      | 4 ++++
 arch/arm64/kvm/hyp/nvhe/hyp-init.S | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
index c87445dde674..c8888891dc8d 100644
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -37,6 +37,10 @@ SYM_TYPED_FUNC_START(cpu_soft_restart)
 	 * regime if HCR_EL2.E2H == 1
 	 */
 	msr	sctlr_el1, x12
+
+	mov_q	x12, INIT_SCTLR2_EL1
+	set_sctlr2_elx	1, x12, x8
+
 	isb
 
 	cbz	x0, 1f				// el2_switch?
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index aada42522e7b..cc569656fe35 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -255,6 +255,9 @@ SYM_CODE_START(__kvm_handle_stub_hvc)
 	mov	x0, xzr
 reset:
 	/* Reset kvm back to the hyp stub. */
+	mov_q 	x5, INIT_SCTLR2_EL2
+	set_sctlr2_elx	2, x5, x4
+
 	mov_q	x5, INIT_SCTLR_EL2_MMU_OFF
 	pre_disable_mmu_workaround
 	msr	sctlr_el2, x5
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}