linux-kernel - RE: [PATCH v3 18/29] arm_mpam: Register and enable IRQs

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Message-ID:
 <OSZPR01MB879875FB57F312EF7086033B8BFAA@OSZPR01MB8798.jpnprd01.prod.outlook.com>
Date: Wed, 29 Oct 2025 07:02:44 +0000
From: "Shaopeng Tan (Fujitsu)" <tan.shaopeng@...itsu.com>
To: 'James Morse' <james.morse@....com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-acpi@...r.kernel.org"
	<linux-acpi@...r.kernel.org>
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	<gregkh@...uxfoundation.org>, Danilo Krummrich <dakr@...nel.org>, Jeremy
 Linton <jeremy.linton@....com>, Gavin Shan <gshan@...hat.com>
Subject: RE: [PATCH v3 18/29] arm_mpam: Register and enable IRQs

> Register and enable error IRQs. All the MPAM error interrupts indicate a
> software bug, e.g. out of range partid. If the error interrupt is ever signalled,
> attempt to disable MPAM.
> 
> Only the irq handler accesses the MPAMF_ESR register, so no locking is
> needed. The work to disable MPAM after an error needs to happen at process
> context as it takes mutex. It also unregisters the interrupts, meaning it can't be
> done from the threaded part of a threaded interrupt.
> Instead, mpam_disable() gets scheduled.
> 
> Enabling the IRQs in the MSC may involve cross calling to a CPU that can
> access the MSC.
> 
> Once the IRQ is requested, the mpam_disable() path can be called
> asynchronously, which will walk structures sized by max_partid. Ensure this
> size is fixed before the interrupt is requested.
> 
> CC: Rohit Mathew <rohit.mathew@....com>
> Tested-by: Rohit Mathew <rohit.mathew@....com>
> Tested-by: Fenghua Yu <fenghuay@...dia.com>
> Signed-off-by: James Morse <james.morse@....com>

Reviewed-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>