linux-kernel - Re: [PATCH v7 2/7] irqchip/gic-v3: Enable support for SGIs to act as NMIs

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Date:   Mon, 2 Nov 2020 11:17:06 -0500
From:   Masayoshi Mizuma <msys.mizuma@...il.com>
To:     Sumit Garg <sumit.garg@...aro.org>
Cc:     maz@...nel.org, catalin.marinas@....com, will@...nel.org,
        daniel.thompson@...aro.org, linux-arm-kernel@...ts.infradead.org,
        tglx@...utronix.de, jason@...edaemon.net, linux@...linux.org.uk,
        tsbogend@...ha.franken.de, mpe@...erman.id.au, davem@...emloft.net,
        mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        mark.rutland@....com, julien.thierry.kdev@...il.com,
        dianders@...omium.org, jason.wessel@...driver.com,
        ito-yuichi@...itsu.com, kgdb-bugreport@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/7] irqchip/gic-v3: Enable support for SGIs to act as
 NMIs

On Mon, Nov 02, 2020 at 05:14:42PM +0530, Sumit Garg wrote:
> Add support to handle SGIs as pseudo NMIs. As SGIs or IPIs default to a
> special flow handler: handle_percpu_devid_fasteoi_ipi(), so skip NMI
> handler update in case of SGIs.
> 
> Also, enable NMI support prior to gic_smp_init() as allocation of SGIs
> as IRQs/NMIs happen as part of this routine.
> 
> Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
> ---
>  drivers/irqchip/irq-gic-v3.c | 29 +++++++++++++++++++++--------
>  1 file changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 16fecc0..7010ae2 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -461,6 +461,7 @@ static u32 gic_get_ppi_index(struct irq_data *d)
>  static int gic_irq_nmi_setup(struct irq_data *d)
>  {
>  	struct irq_desc *desc = irq_to_desc(d->irq);
> +	u32 idx;
>  
>  	if (!gic_supports_nmi())
>  		return -EINVAL;
> @@ -478,16 +479,22 @@ static int gic_irq_nmi_setup(struct irq_data *d)
>  		return -EINVAL;
>  
>  	/* desc lock should already be held */
> -	if (gic_irq_in_rdist(d)) {
> -		u32 idx = gic_get_ppi_index(d);
> +	switch (get_intid_range(d)) {
> +	case SGI_RANGE:
> +		break;
> +	case PPI_RANGE:
> +	case EPPI_RANGE:
> +		idx = gic_get_ppi_index(d);
>  
>  		/* Setting up PPI as NMI, only switch handler for first NMI */
>  		if (!refcount_inc_not_zero(&ppi_nmi_refs[idx])) {
>  			refcount_set(&ppi_nmi_refs[idx], 1);
>  			desc->handle_irq = handle_percpu_devid_fasteoi_nmi;
>  		}
> -	} else {
> +		break;
> +	default:
>  		desc->handle_irq = handle_fasteoi_nmi;
> +		break;
>  	}
>  
>  	gic_irq_set_prio(d, GICD_INT_NMI_PRI);
> @@ -498,6 +505,7 @@ static int gic_irq_nmi_setup(struct irq_data *d)
>  static void gic_irq_nmi_teardown(struct irq_data *d)
>  {
>  	struct irq_desc *desc = irq_to_desc(d->irq);
> +	u32 idx;
>  
>  	if (WARN_ON(!gic_supports_nmi()))
>  		return;
> @@ -515,14 +523,20 @@ static void gic_irq_nmi_teardown(struct irq_data *d)
>  		return;
>  
>  	/* desc lock should already be held */
> -	if (gic_irq_in_rdist(d)) {
> -		u32 idx = gic_get_ppi_index(d);
> +	switch (get_intid_range(d)) {
> +	case SGI_RANGE:
> +		break;
> +	case PPI_RANGE:
> +	case EPPI_RANGE:
> +		idx = gic_get_ppi_index(d);
>  
>  		/* Tearing down NMI, only switch handler for last NMI */
>  		if (refcount_dec_and_test(&ppi_nmi_refs[idx]))
>  			desc->handle_irq = handle_percpu_devid_irq;
> -	} else {
> +		break;
> +	default:
>  		desc->handle_irq = handle_fasteoi_irq;
> +		break;
>  	}
>  
>  	gic_irq_set_prio(d, GICD_INT_DEF_PRI);
> @@ -1708,6 +1722,7 @@ static int __init gic_init_bases(void __iomem *dist_base,
>  
>  	gic_dist_init();
>  	gic_cpu_init();
> +	gic_enable_nmi_support();
>  	gic_smp_init();
>  	gic_cpu_pm_init();
>  
> @@ -1719,8 +1734,6 @@ static int __init gic_init_bases(void __iomem *dist_base,
>  			gicv2m_init(handle, gic_data.domain);
>  	}
>  
> -	gic_enable_nmi_support();
> -
>  	return 0;
>  
>  out_free:
> -- 

Looks good to me. Please feel free to add:

	Reviewed-by: Masayoshi Mizuma <m.mizuma@...fujitsu.com>

Thanks!
Masa