Thread (29 messages) 29 messages, 4 authors, 2026-01-29

Re: [PATCH v2 1/5] arm64/sysreg: Add HDBSS related register information

From: Marc Zyngier <maz@kernel.org>
Date: 2026-01-23 10:15:37
Also in: kvm, kvmarm, linux-doc, lkml

On Thu, 22 Jan 2026 15:12:28 +0000,
Leonardo Bras [off-list ref] wrote:
On Sat, Nov 22, 2025 at 12:40:27PM +0000, Marc Zyngier wrote:
quoted
On Fri, 21 Nov 2025 09:23:38 +0000,
Tian Zheng [off-list ref] wrote:
quoted
From: eillon <redacted>

The ARM architecture added the HDBSS feature and descriptions of
related registers (HDBSSBR/HDBSSPROD) in the DDI0601(ID121123) version,
add them to Linux.

Signed-off-by: eillon <redacted>
Signed-off-by: Tian Zheng <redacted>
---
 arch/arm64/include/asm/esr.h     |  2 ++
 arch/arm64/include/asm/kvm_arm.h |  1 +
 arch/arm64/tools/sysreg          | 28 ++++++++++++++++++++++++++++
 3 files changed, 31 insertions(+)
diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
index e1deed824464..a6f3cf0b9b86 100644
--- a/arch/arm64/include/asm/esr.h
+++ b/arch/arm64/include/asm/esr.h
@@ -159,6 +159,8 @@
 #define ESR_ELx_CM 		(UL(1) << ESR_ELx_CM_SHIFT)

 /* ISS2 field definitions for Data Aborts */
+#define ESR_ELx_HDBSSF_SHIFT	(11)
+#define ESR_ELx_HDBSSF		(UL(1) << ESR_ELx_HDBSSF_SHIFT)
 #define ESR_ELx_TnD_SHIFT	(10)
 #define ESR_ELx_TnD 		(UL(1) << ESR_ELx_TnD_SHIFT)
 #define ESR_ELx_TagAccess_SHIFT	(9)
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 1da290aeedce..b71122680a03 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -124,6 +124,7 @@
 			 TCR_EL2_ORGN0_MASK | TCR_EL2_IRGN0_MASK)

 /* VTCR_EL2 Registers bits */
+#define VTCR_EL2_HDBSS		(1UL << 45)
I think it is time to convert VTCR_EL2 to the sysreg infrastructure
instead of adding extra bits here.

Hi Marc, Tian,

Marc, IIUC the above was implemented by 
https://lore.kernel.org/all/20251210173024.561160-1-maz@kernel.org (local)

Which was recently applied to next, and it its way to mainstream.
Yes.
Tian, I think it's worth rebasing this patchset on top of the above.
Probably not on top of the series, but cherry-picking the patch is
fine. In general, developing anything on top of -next is a terrible
idea.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.
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