linux-kernel - Re: [PATCH v3 0/3] genirq: Managed affinity fixes

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Message-ID: <b14b61cc-ab47-e90d-7f81-f05197645dc6@huawei.com>
Date:   Thu, 7 Apr 2022 18:29:58 +0100
From:   John Garry <john.garry@...wei.com>
To:     Marc Zyngier <maz@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Xiongfeng Wang <wangxiongfeng2@...wei.com>,
        David Decotigny <ddecotig@...gle.com>
Subject: Re: [PATCH v3 0/3] genirq: Managed affinity fixes

On 05/04/2022 19:50, Marc Zyngier wrote:
> John (and later on David) reported[1] a while ago that booting with
> maxcpus=1, managed affinity devices would fail to get the interrupts
> that were associated with offlined CPUs.
> 
> Similarly, Xiongfeng reported[2] that the GICv3 ITS would sometime use
> non-housekeeping CPUs instead of the affinity that was passed down as
> a parameter.
> 
> [1] can be fixed by not trying to activate these interrupts if no CPU
> that can satisfy the affinity is present (a patch addressing this was
> already posted[3])
> 
> [2] is a consequence of affinities containing non-online CPUs being
> passed down to the interrupt controller driver and the ITS driver
> trying to paper over that by ignoring the affinity parameter and doing
> its own (stupid) thing. It would be better to (a) get the core code to
> remove the offline CPUs from the affinity mask at all times, and (b)
> fix the drivers so that they can trust the core code not to trip them.
> 
> This small series, based on 5.18-rc1, addresses the above.

Hi Marc,

Please let me know if you require anything more from me on this one. I 
was hoping that Xiongfeng would verify that his "housekeeping" issues 
were fixed.

Cheers

> 
> Thanks,
> 
> 	M.
> 
>>>From v2 [4]:
>    - Rebased on 5.18-rc1
> 
> [1] https://lore.kernel.org/r/78615d08-1764-c895-f3b7-bfddfbcbdfb9@huawei.com
> [2] https://lore.kernel.org/r/20220124073440.88598-1-wangxiongfeng2@huawei.com
> [3] https://lore.kernel.org/r/20220307190625.254426-1-maz@kernel.org
> [4] https://lore.kernel.org/r/20220321193608.975495-1-maz@kernel.org
> 
> Marc Zyngier (3):
>    genirq/msi: Shutdown managed interrupts with unsatifiable affinities
>    genirq: Always limit the affinity to online CPUs
>    irqchip/gic-v3: Always trust the managed affinity provided by the core
>      code
> 
>   drivers/irqchip/irq-gic-v3-its.c |  2 +-
>   kernel/irq/manage.c              | 25 +++++++++++++++++--------
>   kernel/irq/msi.c                 | 15 +++++++++++++++
>   3 files changed, 33 insertions(+), 9 deletions(-)
>