linux-kernel - Re: [PATCH v2 20/29] arm_mpam: Allow configuration to be applied and restored during cpu online

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Message-ID: <5eb4b7f0-37eb-47c9-a955-ed9db17fa1e5@arm.com>
Date: Fri, 12 Sep 2025 16:00:30 +0100
From: Ben Horgan <ben.horgan@....com>
To: James Morse <james.morse@....com>, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org
Cc: D Scott Phillips OS <scott@...amperecomputing.com>,
 carl@...amperecomputing.com, lcherian@...vell.com,
 bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
 baolin.wang@...ux.alibaba.com, Jamie Iles <quic_jiles@...cinc.com>,
 Xin Hao <xhao@...ux.alibaba.com>, peternewman@...gle.com,
 dfustini@...libre.com, amitsinght@...vell.com,
 David Hildenbrand <david@...hat.com>, Dave Martin <dave.martin@....com>,
 Koba Ko <kobak@...dia.com>, Shanker Donthineni <sdonthineni@...dia.com>,
 fenghuay@...dia.com, baisheng.gao@...soc.com,
 Jonathan Cameron <jonathan.cameron@...wei.com>, Rob Herring
 <robh@...nel.org>, Rohit Mathew <rohit.mathew@....com>,
 Rafael Wysocki <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
 Lorenzo Pieralisi <lpieralisi@...nel.org>, Hanjun Guo
 <guohanjun@...wei.com>, Sudeep Holla <sudeep.holla@....com>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Danilo Krummrich <dakr@...nel.org>
Subject: Re: [PATCH v2 20/29] arm_mpam: Allow configuration to be applied and
 restored during cpu online

Hi James,

On 9/10/25 21:43, James Morse wrote:
> When CPUs come online the MSC's original configuration should be restored.
> 
> Add struct mpam_config to hold the configuration. This has a bitmap of
> features that were modified. Once the maximum partid is known, allocate
> a configuration array for each component, and reprogram each RIS
> configuration from this.
> 
> CC: Dave Martin <Dave.Martin@....com>
> Signed-off-by: James Morse <james.morse@....com>
> ---
> Changes since v1:
>  * Switched entry_rcu to srcu versions.
> 
> Changes since RFC:
>  * Added a comment about the ordering around max_partid.
>  * Allocate configurations after interrupts are registered to reduce churn.
>  * Added mpam_assert_partid_sizes_fixed();
>  * Make reset use an all-ones instead of zero config.
> ---
>  drivers/resctrl/mpam_devices.c  | 269 +++++++++++++++++++++++++++++---
>  drivers/resctrl/mpam_internal.h |  29 +++-
>  2 files changed, 271 insertions(+), 27 deletions(-)
> 

Reviewed-by: Ben Horgan <ben.horgan@....com>
Thanks,

Ben