linux-kernel - Re: [PATCH v5 3/5] arm64: smp: Allocate and setup IPI as NMI

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Message-ID: <1c68b74251dc72b0cd74706280ea96f7@kernel.org>
Date:   Mon, 19 Oct 2020 12:59:42 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Sumit Garg <sumit.garg@...aro.org>
Cc:     catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, tglx@...utronix.de,
        jason@...edaemon.net, mark.rutland@....com,
        julien.thierry.kdev@...il.com, dianders@...omium.org,
        daniel.thompson@...aro.org, jason.wessel@...driver.com,
        msys.mizuma@...il.com, ito-yuichi@...itsu.com,
        kgdb-bugreport@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/5] arm64: smp: Allocate and setup IPI as NMI

On 2020-10-14 12:12, Sumit Garg wrote:
> Allocate an unused IPI that can be turned as NMI using ipi_nmi 
> framework.

This doesn't do any allocation, as far as I can see. It relies on
the initial grant from the interrupt controller to be larger than
what the kernel currently uses.

> Also, invoke corresponding NMI setup/teardown APIs.
> 
> Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
> ---
>  arch/arm64/kernel/smp.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 82e75fc..129ebfb 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -43,6 +43,7 @@
>  #include <asm/daifflags.h>
>  #include <asm/kvm_mmu.h>
>  #include <asm/mmu_context.h>
> +#include <asm/nmi.h>
>  #include <asm/numa.h>
>  #include <asm/processor.h>
>  #include <asm/smp_plat.h>
> @@ -962,6 +963,8 @@ static void ipi_setup(int cpu)
> 
>  	for (i = 0; i < nr_ipi; i++)
>  		enable_percpu_irq(ipi_irq_base + i, 0);
> +
> +	ipi_nmi_setup(cpu);
>  }
> 
>  #ifdef CONFIG_HOTPLUG_CPU
> @@ -974,6 +977,8 @@ static void ipi_teardown(int cpu)
> 
>  	for (i = 0; i < nr_ipi; i++)
>  		disable_percpu_irq(ipi_irq_base + i);
> +
> +	ipi_nmi_teardown(cpu);
>  }
>  #endif
> 
> @@ -995,6 +1000,9 @@ void __init set_smp_ipi_range(int ipi_base, int n)
>  		irq_set_status_flags(ipi_base + i, IRQ_HIDDEN);
>  	}
> 
> +	if (n > nr_ipi)
> +		set_smp_ipi_nmi(ipi_base + nr_ipi);
> +
>  	ipi_irq_base = ipi_base;
> 
>  	/* Setup the boot CPU immediately */

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...