From: Marc Zyngier <maz@kernel.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Oliver Upton <oupton@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: Clear VTCR_EL2 in __init_el2_stage2()
Date: Fri, 13 Mar 2026 09:06:14 +0000 [thread overview]
Message-ID: <87ms0ccd4p.wl-maz@kernel.org> (raw)
In-Reply-To: <949f02cf-9f26-40ba-9c68-1742e335e2b9@arm.com>
On Fri, 13 Mar 2026 08:39:46 +0000,
Anshuman Khandual <anshuman.khandual@arm.com> wrote:
>
>
>
> On 13/03/26 1:41 PM, Marc Zyngier wrote:
> > On Fri, 13 Mar 2026 07:54:04 +0000,
> > Anshuman Khandual <anshuman.khandual@arm.com> wrote:
> >>
> >> But it can be argued that these registers
> >> need not have to be cleared now and can just be initialised before
> >> setting up HCR_EL2_VM itself. In which case should we drop
> >> __init_el2_stage2() entirely ?
> >
> > And something worth thinking of: the role of VTTBR_EL2.VMID when
> > HCR_EL2.VM is 0.
>
> Are you suggesting that VTTBR_EL2_VMID needs to be 0 even when
> HCR_EL2_VM = 0 because of its corresponding TLB entries ? But
> during system boot such possibilities might not really exist ?
This is not a suggestion. This is an architectural requirement.
TLBs filled from the EL1&0 translation regime are always tagged by
VMID when EL2 is implemented, irrespective of HCR_EL2.VM.
M.
--
Jazz isn't dead. It just smells funny.
next prev parent reply other threads:[~2026-03-13 9:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-13 5:38 [PATCH] arm64: Clear VTCR_EL2 in __init_el2_stage2() Anshuman Khandual
2026-03-13 7:25 ` Marc Zyngier
2026-03-13 7:54 ` Anshuman Khandual
2026-03-13 8:07 ` Marc Zyngier
2026-03-13 8:11 ` Marc Zyngier
2026-03-13 8:39 ` Anshuman Khandual
2026-03-13 9:06 ` Marc Zyngier [this message]
2026-03-13 9:59 ` Mark Rutland
2026-03-17 2:46 ` Anshuman Khandual
2026-03-17 9:15 ` Marc Zyngier
2026-03-17 10:16 ` Mark Rutland
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