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From: Pingfan Liu <kernelfans@gmail.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	Julien Thierry <julien.thierry@arm.com>
Subject: Re: [PATCH] arm64/irq: use NMI to send stop IPI
Date: Mon, 14 Dec 2020 10:20:15 +0800	[thread overview]
Message-ID: <CAFgQCTvLud2qOWfSDK_HbKwid-2uLPDA_Uz-iTQzBYiWwqJX5Q@mail.gmail.com> (raw)
In-Reply-To: <afd82be798cb55fd2f96940db7be78c0@kernel.org>

On Tue, Dec 8, 2020 at 10:04 PM Marc Zyngier <maz@kernel.org> wrote:
>
> On 2020-12-08 13:14, Pingfan Liu wrote:
> > Like other arches, both 'kexec -l' and 'kexec -p' expect to use NMI to
> > interrupt other cpus in order to capture cpus tightly to a known state.
> >
> > So for both of the cases, try to use NMI IPI if irqchip supports NMI.
>
> There are at least 2 other competing series doing the same thing,
> and (ab)using NMIs for dubious purposes (kexec, kgdb...)
>
I think kexec has a good justification, but start with (2) at present.
> (1) Please work with others instead of reinventing things from scratch,
>      with similar problems
>
I will.
> (2) No additional NMI patches will make it until we have resolved the
> issues
>      described in [1], which is likely to take some time
>
After serval days of chasing this issue, I have a raw idea about it.
What about re-structure the code like
DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_reschedule_ipi) ?

I will send a series soon afterward.

Thanks,
Pingfan

> Thanks,
>
>          M.
>
> [1]
> https://lore.kernel.org/linux-arm-kernel/87lfewnmdz.fsf@nanos.tec.linutronix.de/
> --
> Jazz is not dead. It just smells funny...

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  reply	other threads:[~2020-12-14  2:22 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-08 13:14 [PATCH] arm64/irq: use NMI to send stop IPI Pingfan Liu
2020-12-08 14:04 ` Marc Zyngier
2020-12-14  2:20   ` Pingfan Liu [this message]
2020-12-14  2:25     ` [PATCH 1/3] kernel/irq: __handle_domain_irq() makes irq_enter/exit arch optional Pingfan Liu
2020-12-14  2:25       ` [PATCH 2/3] arm64/irq-gic-v3: make gic_handle_irq() cope with enter_from_kernel_mode() Pingfan Liu
2020-12-14  2:25       ` [PATCH 3/3] arm64/irq-gic-v3: make reschedule-ipi light weight Pingfan Liu
2020-12-14  9:46     ` [PATCH] arm64/irq: use NMI to send stop IPI Marc Zyngier
2020-12-14 13:04       ` Pingfan Liu
2020-12-14 13:24         ` Marc Zyngier
2020-12-15  5:40           ` Pingfan Liu

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