linux-kernel - Re: [PATCH 1/2] irqchip/mips-gic: Don't touch vl

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Date:   Sun, 14 May 2023 16:41:43 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Jiaxun Yang <jiaxun.yang@...goat.com>
Cc:     maz@...nel.org, tsbogend@...ha.franken.de, tglx@...utronix.de,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH 1/2] irqchip/mips-gic: Don't touch vl_map if a local
 interrupt is not routable

Hello Jiaxun

On Mon, Apr 24, 2023 at 11:31:55AM +0100, Jiaxun Yang wrote:
> When a GIC local interrupt is not routable, it's vl_map will be used
> to control some internal states for core (providing IPTI, IPPCI, IPFDC

> input signal for core). Overriding it will interfere core's intetrupt

s/intetrupt/interrupt

> controller.
> 
> Do not touch vl_map if a local interrupt is not routable, we are not
> going to remap it.
> 
> Before dd098a0e0319 (" irqchip/mips-gic: Get rid of the reliance on
> irq_cpu_online()"), if a local interrupt is not routable, then it won't
> be requested from GIC Local domain, and thus gic_all_vpes_irq_cpu_online
> won't be called for that particular interrupt.
> 
> Fixes: dd098a0e0319 (" irqchip/mips-gic: Get rid of the reliance on irq_cpu_online()")
> Cc: stable@...r.kernel.org
> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>

My system doesn't have VPEs but 2x MIPS32 P5600 cores with GIC enabled as
EIC device so I can't fully test this change, but at the very least it
looks reasonable. Indeed performing the local IRQs routing setups for
the non-routable IRQs looks invalid. A similar change can be spotted
in the gic_irq_domain_map() method implementation.

> ---
>  drivers/irqchip/irq-mips-gic.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
> index 046c355e120b..b568d55ef7c5 100644
> --- a/drivers/irqchip/irq-mips-gic.c
> +++ b/drivers/irqchip/irq-mips-gic.c
> @@ -399,6 +399,8 @@ static void gic_all_vpes_irq_cpu_online(void)
>  		unsigned int intr = local_intrs[i];
>  		struct gic_all_vpes_chip_data *cd;
>  
> +		if (!gic_local_irq_is_routable(intr))
> +			continue;

Please add newline here to distinguish the skip-step code chunk and
the setup code so the look would look a tiny bit more readable.

>  		cd = &gic_all_vpes_chip_data[intr];
>  		write_gic_vl_map(mips_gic_vx_map_reg(intr), cd->map);
>  		if (cd->mask)

Other than that the change looks good. Thanks.

Reviewed-by: Serge Semin <fancer.lancer@...il.com>

-Serge(y)

> -- 
> 2.34.1
>