linux-kernel - Re: [PATCH v2 0/3] genirq: Managed affinity fixes

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Message-ID: <a83da394-dcc0-c9a6-1569-9c30fbc291fd@huawei.com>
Date:   Wed, 23 Mar 2022 11:52:46 +0800
From:   Xiongfeng Wang <wangxiongfeng2@...wei.com>
To:     Marc Zyngier <maz@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        John Garry <john.garry@...wei.com>,
        David Decotigny <ddecotig@...gle.com>
Subject: Re: [PATCH v2 0/3] genirq: Managed affinity fixes

Hi, Marc

On 2022/3/22 3:36, 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 5.17, addresses the above.

I have tested this patchset on D06. It works well with kernel parameter
'maxcpus=1' or 'nohz_full=1-127 isolcpus=nohz,domain,managed_irq,1-127'.
Also the 'effective_affinity' is correct. Thanks!
By the way, I merged the second patch manually because of conflicts.
Maybe I lack some patches on your local repo.

Thanks,
Xiongfeng

> 
> Thanks,
> 
> 	M.
> 
> [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
> 
> 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(-)
>