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From: Valentin Schneider <valentin.schneider@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: Sumit Garg <sumit.garg@linaro.org>,
	kernel-team@android.com, Russell King <linux@arm.linux.org.uk>,
	Jason Cooper <jason@lakedaemon.net>,
	Catalin Marinas <catalin.marinas@arm.com>,
	linux-kernel@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 03/11] arm64: Allow IPIs to be handled as normal interrupts
Date: Thu, 21 May 2020 15:03:29 +0100
Message-ID: <jhjlfllxu4u.mognet@arm.com> (raw)
In-Reply-To: <20200519161755.209565-4-maz@kernel.org>


On 19/05/20 17:17, Marc Zyngier wrote:
> In order to deal with IPIs as normal interrupts, let's add
> a new way to register them with the architecture code.
>
> set_smp_ipi_range() takes a range of interrupts, and allows
> the arch code to request them as if the were normal interrupts.
                                      ^^^
                                  s/the/they/

> A standard handler is then called by the core IRQ code to deal
> with the IPI.
>
> This means that we don't need to call irq_enter/irq_exit, and
> that we don't need to deal with set_irq_regs either. So let's
> move the dispatcher into its own function, and leave handle_IPI()
> as a compatibility function.
>
> On the sending side, let's make use of ipi_send_mask, which
> already exists for this purpose.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  arch/arm64/Kconfig           |  1 +
>  arch/arm64/include/asm/smp.h |  5 ++
>  arch/arm64/kernel/smp.c      | 92 +++++++++++++++++++++++++++++++-----
>  3 files changed, 86 insertions(+), 12 deletions(-)
>
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 061f60fe452f..93ba0025e7b9 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -247,6 +254,8 @@ asmlinkage notrace void secondary_start_kernel(void)
>        */
>       notify_cpu_starting(cpu);
>
> +	ipi_setup(cpu);
> +
>       store_cpu_topology(cpu);
>       numa_add_cpu(cpu);
>
> @@ -374,6 +383,8 @@ void cpu_die(void)
>
>       local_daif_mask();
>
> +	ipi_teardown(cpu);
> +

Would it make sense to move it up to say __cpu_disable()? I'm thinking it
would make sense to bunch this up with the toggling of the cpu_online_mask
bit, and FWIW it'd match with the comment atop the cpuhp callsite.

Once the CPU is set as offline, all it has left to do is to go die in
do_idle(), so AFAICT we can do that IPI teardown anywhere inbetween.

>       /* Tell __cpu_die() that this CPU is now safe to dispose of */
>       (void)cpu_report_death();
>

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  reply index

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-19 16:17 [PATCH 00/11] arm/arm64: Turning IPIs into " Marc Zyngier
2020-05-19 16:17 ` [PATCH 01/11] genirq: Add fasteoi IPI flow Marc Zyngier
2020-05-19 19:47   ` Florian Fainelli
2020-06-12  9:54     ` Marc Zyngier
2020-05-19 22:25   ` Valentin Schneider
2020-05-19 22:29     ` Valentin Schneider
2020-06-12  9:58     ` Marc Zyngier
2020-05-19 16:17 ` [PATCH 02/11] genirq: Allow interrupts to be excluded from /proc/interrupts Marc Zyngier
2020-05-19 16:17 ` [PATCH 03/11] arm64: Allow IPIs to be handled as normal interrupts Marc Zyngier
2020-05-21 14:03   ` Valentin Schneider [this message]
2020-05-19 16:17 ` [PATCH 04/11] ARM: " Marc Zyngier
2020-05-19 22:24   ` Russell King - ARM Linux admin
2020-05-21 14:03     ` Valentin Schneider
2020-05-21 15:12       ` Russell King - ARM Linux admin
2020-05-21 16:11         ` Valentin Schneider
2020-05-19 16:17 ` [PATCH 05/11] irqchip/gic-v3: Describe the SGI range Marc Zyngier
2020-05-19 16:17 ` [PATCH 06/11] irqchip/gic-v3: Configure SGIs as standard interrupts Marc Zyngier
2020-05-20  9:52   ` Sumit Garg
2020-05-20 10:24     ` Marc Zyngier
2020-05-21 14:04   ` Valentin Schneider
2020-06-12 10:39     ` Marc Zyngier
2020-05-19 16:17 ` [PATCH 07/11] irqchip/gic: Refactor SMP configuration Marc Zyngier
2020-05-19 16:17 ` [PATCH 08/11] irqchip/gic: Configure SGIs as standard interrupts Marc Zyngier
2021-04-20 20:37   ` dann frazier
2021-04-20 21:25     ` dann frazier
2021-04-21 10:58       ` Marc Zyngier
2021-04-21 14:52         ` dann frazier
2021-04-21 15:49           ` Marc Zyngier
2020-05-19 16:17 ` [PATCH 09/11] irqchip/gic-common: Don't enable SGIs by default Marc Zyngier
2020-05-19 16:17 ` [PATCH 10/11] irqchip/bcm2836: Configure mailbox interrupts as standard interrupts Marc Zyngier
2020-05-19 16:17 ` [PATCH 11/11] arm64: Kill __smp_cross_call and co Marc Zyngier
2020-05-19 17:50 ` [PATCH 00/11] arm/arm64: Turning IPIs into normal interrupts Florian Fainelli
2020-05-19 19:47   ` Florian Fainelli
2020-06-12  9:49   ` Marc Zyngier
2020-06-12 16:57     ` Florian Fainelli
2020-05-19 22:25 ` Valentin Schneider

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