linux-kernel - Re: [RFC PATCH 01/33] irqchip/gic-v3: Add redistributor iterator

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Message-ID: <22a9cb20-f5f0-20e7-e34c-f14847a35e5e@redhat.com>
Date:   Thu, 16 Feb 2017 13:47:44 +0100
From:   Auger Eric <eric.auger@...hat.com>
To:     Marc Zyngier <marc.zyngier@....com>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Christoffer Dall <christoffer.dall@...aro.org>
Subject: Re: [RFC PATCH 01/33] irqchip/gic-v3: Add redistributor iterator

Hi Marc,

On 17/01/2017 11:20, Marc Zyngier wrote:
> In order to discover the VLPI properties, we need to iterate over
> the redistributor regions. As we already have code that does this,
> let's factor it out and make it slightly more generic.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
>  drivers/irqchip/irq-gic-v3.c | 77 ++++++++++++++++++++++++++++++++------------
>  1 file changed, 56 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index c132f29..5cadec0 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -421,24 +421,15 @@ static void __init gic_dist_init(void)
>  		gic_write_irouter(affinity, base + GICD_IROUTER + i * 8);
>  }
>  
> -static int gic_populate_rdist(void)
> +static int gic_scan_rdist_properties(int (*fn)(struct redist_region *,
> +					       void __iomem *))
>  {
> -	unsigned long mpidr = cpu_logical_map(smp_processor_id());
> -	u64 typer;
> -	u32 aff;
> +	int ret = 0;
in case
if (reg != GIC_PIDR2_ARCH_GICv3 &&
		    reg != GIC_PIDR2_ARCH_GICv4) is true you now return 0. Don' you
want to return -ENODEV as before?


>  	int i;
>  
> -	/*
> -	 * Convert affinity to a 32bit value that can be matched to
> -	 * GICR_TYPER bits [63:32].
> -	 */
> -	aff = (MPIDR_AFFINITY_LEVEL(mpidr, 3) << 24 |
> -	       MPIDR_AFFINITY_LEVEL(mpidr, 2) << 16 |
> -	       MPIDR_AFFINITY_LEVEL(mpidr, 1) << 8 |
> -	       MPIDR_AFFINITY_LEVEL(mpidr, 0));
> -
>  	for (i = 0; i < gic_data.nr_redist_regions; i++) {
>  		void __iomem *ptr = gic_data.redist_regions[i].redist_base;
> +		u64 typer;
>  		u32 reg;
>  
>  		reg = readl_relaxed(ptr + GICR_PIDR2) & GIC_PIDR2_ARCH_MASK;
> @@ -450,14 +441,14 @@ static int gic_populate_rdist(void)
>  
>  		do {
>  			typer = gic_read_typer(ptr + GICR_TYPER);
> -			if ((typer >> 32) == aff) {
> -				u64 offset = ptr - gic_data.redist_regions[i].redist_base;
> -				gic_data_rdist_rd_base() = ptr;
> -				gic_data_rdist()->phys_base = gic_data.redist_regions[i].phys_base + offset;
> -				pr_info("CPU%d: found redistributor %lx region %d:%pa\n",
> -					smp_processor_id(), mpidr, i,
> -					&gic_data_rdist()->phys_base);
> +			ret = fn(gic_data.redist_regions + i, ptr);
> +			switch (ret) {
> +			case 0:
>  				return 0;
> +			case -1:
> +				break;
> +			default:
> +				ret = 0;
>  			}
>  
>  			if (gic_data.redist_regions[i].single_redist)
> @@ -473,9 +464,53 @@ static int gic_populate_rdist(void)
>  		} while (!(typer & GICR_TYPER_LAST));
>  	}
Assuming you don't find the TYPER that matches the cpu (I don't know if
it is possible), last fn() call will return 1 and the function will
return 0. Before it returned -ENODEV I think.

Thanks

Eric
>  
> +	if (ret == -1)
> +		ret = -ENODEV;
> +
> +	return 0;
> +}
> +
> +static int __gic_populate_rdist(struct redist_region *region, void __iomem *ptr)
> +{
> +	unsigned long mpidr = cpu_logical_map(smp_processor_id());
> +	u64 typer;
> +	u32 aff;
> +
> +	/*
> +	 * Convert affinity to a 32bit value that can be matched to
> +	 * GICR_TYPER bits [63:32].
> +	 */
> +	aff = (MPIDR_AFFINITY_LEVEL(mpidr, 3) << 24 |
> +	       MPIDR_AFFINITY_LEVEL(mpidr, 2) << 16 |
> +	       MPIDR_AFFINITY_LEVEL(mpidr, 1) << 8 |
> +	       MPIDR_AFFINITY_LEVEL(mpidr, 0));
> +
> +	typer = gic_read_typer(ptr + GICR_TYPER);
> +	if ((typer >> 32) == aff) {
> +		u64 offset = ptr - region->redist_base;
> +		gic_data_rdist_rd_base() = ptr;
> +		gic_data_rdist()->phys_base = region->phys_base + offset;
> +
> +		pr_info("CPU%d: found redistributor %lx region %d:%pa\n",
> +			smp_processor_id(), mpidr,
> +			(int)(region - gic_data.redist_regions),
> +			&gic_data_rdist()->phys_base);
> +		return 0;
> +	}
> +
> +	/* Try next one */
> +	return 1;
> +}
> +
> +static int gic_populate_rdist(void)
> +{
> +	if (gic_scan_rdist_properties(__gic_populate_rdist) == 0)
> +		return 0;
> +
>  	/* We couldn't even deal with ourselves... */
>  	WARN(true, "CPU%d: mpidr %lx has no re-distributor!\n",
> -	     smp_processor_id(), mpidr);
> +	     smp_processor_id(),
> +	     (unsigned long)cpu_logical_map(smp_processor_id()));
>  	return -ENODEV;
>  }
>  
>