From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Marc Zyngier <maz@kernel.org>,
kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
kvm@vger.kernel.org
Cc: Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Ard Biesheuvel <ardb@kernel.org>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Oliver Upton <oliver.upton@linux.dev>,
Zenghui Yu <yuzenghui@huawei.com>
Subject: Re: [PATCH v2 0/3] arm64: Drop support for VPIPT i-cache policy
Date: Wed, 29 Nov 2023 12:01:18 +0530 [thread overview]
Message-ID: <083c8502-9a0d-4876-b60a-bc26bb2ebabf@arm.com> (raw)
In-Reply-To: <20231127172613.1490283-1-maz@kernel.org>
On 11/27/23 22:56, Marc Zyngier wrote:
> ARMv8.2 introduced support for VPIPT i-caches, the V standing for
> VMID-tagged. Although this looks like a reasonable idea, no
> implementation has ever made it into the wild.
>
> Linux has supported this for over 6 years (amusingly, just as the
> architecture was dropping support for AVIVT i-caches), but we had no
> way to even test it, and it is likely that this code was just
> bit-rotting.
>
> However, in a recent breakthrough (XML drop 2023-09, tagged as
> d55f5af8e09052abe92a02adf820deea2eaed717), the architecture has
> finally been purged of this option, making VIPT and PIPT the only two
> valid options.
Indeed, FEAT_VPIPT has been dropped from the 2023-09 document release.
https://developer.arm.com/documentation/ddi0601/2023-06/AArch64-Registers/CTR-EL0--Cache-Type-Register
CTR_EL0.L1Ip[15:14] = 00 - VMID aware Physical Index, Physical tag (VPIPT) with FEAT_VPIPT
https://developer.arm.com/documentation/ddi0601/2023-09/AArch64-Registers/CTR-EL0--Cache-Type-Register
CTR_EL0.L1Ip[15:14] = 00 - Reserved.
next prev parent reply other threads:[~2023-11-29 6:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-27 17:26 [PATCH v2 0/3] arm64: Drop support for VPIPT i-cache policy Marc Zyngier
2023-11-27 17:26 ` [PATCH v2 1/3] KVM: arm64: Remove VPIPT I-cache handling Marc Zyngier
2023-11-29 7:36 ` Anshuman Khandual
2023-11-27 17:26 ` [PATCH v2 2/3] arm64: Kill detection of VPIPT i-cache policy Marc Zyngier
2023-11-29 7:25 ` Anshuman Khandual
2023-11-27 17:26 ` [PATCH v2 3/3] arm64: Rename reserved values for CTR_EL0.L1Ip Marc Zyngier
2023-11-29 7:13 ` Anshuman Khandual
2023-11-29 13:06 ` Marc Zyngier
2023-11-29 6:31 ` Anshuman Khandual [this message]
2023-12-04 13:09 ` [PATCH v2 0/3] arm64: Drop support for VPIPT i-cache policy Zenghui Yu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=083c8502-9a0d-4876-b60a-bc26bb2ebabf@arm.com \
--to=anshuman.khandual@arm.com \
--cc=ardb@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=james.morse@arm.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.org \
--cc=oliver.upton@linux.dev \
--cc=suzuki.poulose@arm.com \
--cc=will@kernel.org \
--cc=yuzenghui@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox