linux-kernel - Re: [PATCH v4 08/41] arm64: mpam: Add cpu

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Message-ID: <aYTLPqpRmwDap6fM@arm.com>
Date: Thu, 5 Feb 2026 16:54:22 +0000
From: Catalin Marinas <catalin.marinas@....com>
To: Ben Horgan <ben.horgan@....com>
Cc: amitsinght@...vell.com, baisheng.gao@...soc.com,
	baolin.wang@...ux.alibaba.com, carl@...amperecomputing.com,
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	jonathan.cameron@...wei.com, kobak@...dia.com, lcherian@...vell.com,
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	Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Subject: Re: [PATCH v4 08/41] arm64: mpam: Add cpu_pm notifier to restore
 MPAM sysregs

On Tue, Feb 03, 2026 at 09:43:09PM +0000, Ben Horgan wrote:
> From: James Morse <james.morse@....com>
> 
> The MPAM system registers will be lost if the CPU is reset during PSCI's
> CPU_SUSPEND.
> 
> Add a PM notifier to restore them.
> 
> mpam_thread_switch(current) can't be used as this won't make any changes if
> the in-memory copy says the register already has the correct value. In
> reality the system register is UNKNOWN out of reset.
> 
> Tested-by: Gavin Shan <gshan@...hat.com>
> Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> Tested-by: Peter Newman <peternewman@...gle.com>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
> Reviewed-by: Gavin Shan <gshan@...hat.com>
> Signed-off-by: James Morse <james.morse@....com>
> Signed-off-by: Ben Horgan <ben.horgan@....com>

Reviewed-by: Catalin Marinas <catalin.marinas@....com>