linux-kernel - [PATCH v3 1/5] arm64: make SCTLR2

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Message-Id: <20250813120118.3953541-2-yeoreum.yun@arm.com>
Date: Wed, 13 Aug 2025 13:01:14 +0100
From: Yeoreum Yun <yeoreum.yun@....com>
To: catalin.marinas@....com,
	will@...nel.org,
	broonie@...nel.org,
	oliver.upton@...ux.dev,
	anshuman.khandual@....com,
	robh@...nel.org,
	james.morse@....com,
	mark.rutland@....com,
	joey.gouly@....com,
	Dave.Martin@....com,
	ahmed.genidi@....com,
	kevin.brodsky@....com,
	scott@...amperecomputing.com,
	mbenes@...e.cz,
	james.clark@...aro.org,
	frederic@...nel.org,
	rafael@...nel.org,
	pavel@...nel.org,
	ryan.roberts@....com,
	suzuki.poulose@....com
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>,
	Marc Zyngier <maz@...nel.org>
Subject: [PATCH v3 1/5] arm64: make SCTLR2_EL1 accessible

When the kernel runs at EL1, and yet is booted at EL2,
HCRX_EL2.SCTLR2En must be set to avoid trapping SCTLR2_EL1 accesses
from EL1 to EL2.

Ensure this bit is set at the point of initialising EL2.

Signed-off-by: Yeoreum Yun <yeoreum.yun@....com>
Reviewed-by: Marc Zyngier <maz@...nel.org>
---
 arch/arm64/include/asm/el2_setup.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
index 46033027510c..d755b4d46d77 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -57,9 +57,15 @@
         /* Enable GCS if supported */
 	mrs_s	x1, SYS_ID_AA64PFR1_EL1
 	ubfx	x1, x1, #ID_AA64PFR1_EL1_GCS_SHIFT, #4
-	cbz	x1, .Lset_hcrx_\@
+	cbz	x1, .Lskip_hcrx_GCSEn_\@
 	orr	x0, x0, #HCRX_EL2_GCSEn
 
+.Lskip_hcrx_GCSEn_\@:
+	mrs_s	x1, SYS_ID_AA64MMFR3_EL1
+	ubfx	x1, x1, #ID_AA64MMFR3_EL1_SCTLRX_SHIFT, #4
+	cbz	x1, .Lset_hcrx_\@
+	orr	x0, x0, HCRX_EL2_SCTLR2En
+
 .Lset_hcrx_\@:
 	msr_s	SYS_HCRX_EL2, x0
 .Lskip_hcrx_\@:
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}