linux-kernel - Re: [PATCH] arm64: cpufeature: Add support for the MPAM v0.1 architecture version

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <37f87d5d-bd70-4b13-93e0-8024108be948@arm.com>
Date: Tue, 27 Jan 2026 14:30:37 +0000
From: Ben Horgan <ben.horgan@....com>
To: Zeng Heng <zengheng4@...wei.com>, james.morse@....com,
 miko.lenczewski@....com, thuth@...hat.com, mark.rutland@....com,
 yeoreum.yun@....com, robh@...nel.org, james.clark@...aro.org,
 ahmed.genidi@....com, xry111@...111.site, oupton@...nel.org,
 lpieralisi@...nel.org, catalin.marinas@....com, mrigendra.chaubey@...il.com,
 suzuki.poulose@....com, maz@...nel.org, ardb@...nel.org, broonie@...nel.org,
 will@...nel.org, kevin.brodsky@....com, leo.yan@....com,
 anshuman.khandual@....com, yang@...amperecomputing.com, frederic@...nel.org
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 bobo.shaobowang@...wei.com
Subject: Re: [PATCH] arm64: cpufeature: Add support for the MPAM v0.1
 architecture version

Hi Zeng,

On 1/4/26 13:34, Zeng Heng wrote:
> According to the MPAM spec [1], the supported architecture versions are
> v1.0, v1.1 and v0.1. MPAM versions v0.1 and v1.1 are functionally
> identical, but v0.1 additionally supports the FORCE_NS feature.
> 
> ID_AA64PR | ID_AA64PR | MPAM Extension | Notes
> F0_EL1.   | F1_EL1.   | Architecture   |
> MPAM      | MPAM_frac | version        |
> ---------------------------------------------------------------------------
> 0b0000    | 0b0001    | v0.1           | MPAM v0.1 is implemented.
>           |           |                | MPAM v0.1 is the same as MPAM v1.1
>           |           |                | with FORCE_NS which is
>           |           |                | incompatible with MPAM v1.0.
> ---------------------------------------------------------------------------
> 0b0001    | 0b0000    | v1.0           | MPAM v1.0 is implemented.
> ---------------------------------------------------------------------------
> 0b0001    | 0b0001    | v1.1           | MPAM v1.1 is implemented.
>           |           |                | MPAM v1.1 includes all features of
>           |           |                | MPAM v1.0.
>           |           |                | It must not include FORCE_NS.
> 
> FORCE_NS is a feature that operates in EL3 mode. Consequently, the current
> Linux MPAM driver is also compatible with MPAM v0.1. To support v0.1, the
> existing driver which only checks ID_AA64PFR0_EL1.MPAM for the major
> version needs to examine ID_AA64PFR1_EL1.MPAM_frac for the minor version
> as well.
> 
> [1] https://developer.arm.com/documentation/ddi0598/db/?lang=en
> 
> Signed-off-by: Zeng Heng <zengheng4@...wei.com>
So far we've avoided added MPAM 0.1 support as we don't know of any
machines using it. What's your motivation here? Do you have a machine
with MPAM 0.1 that runs mainline linux?

Thanks,

Ben