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

[Tian Zheng]

On 1/22/2026 11:12 PM, Leonardo Bras wrote:
> On Sat, Nov 22, 2025 at 12:40:27PM +0000, Marc Zyngier wrote:
> > On Fri, 21 Nov 2025 09:23:38 +0000,
> > Tian Zheng <zhengtian10@xxxxxxxxxx> wrote:
> > > From: eillon <yezhenyu2@xxxxxxxxxx>
> > >
> > > 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 <yezhenyu2@xxxxxxxxxx>
> > > Signed-off-by: Tian Zheng <zhengtian10@xxxxxxxxxx>
> > > ---
> > >   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@xxxxxxxxxx
>
> Which was recently applied to next, and it its way to mainstream.
>
> Tian, I think it's worth rebasing this patchset on top of the above.

Indeed, I've been following Marc's VTCR_EL2 patch and will rebase my
changes on top of it.

> BTW, I am working on using the feature enabled by this patchset on a new
> optimization, so please include me on any new release.

Sure, I'll make sure you're on the Cc list for the next revision.

> Thanks!
> Leo