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From: Ian Munsie <imunsie@au1.ibm.com>
To: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Cc: Michael Neuling <michael.neuling@au1.ibm.com>,
 linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v3 08/18] cxl: IRQ allocation for guests
In-reply-to: <1454765345-7417-9-git-send-email-fbarrat@linux.vnet.ibm.com>
References: <1454765345-7417-1-git-send-email-fbarrat@linux.vnet.ibm.com>
 <1454765345-7417-9-git-send-email-fbarrat@linux.vnet.ibm.com>
Date: Wed, 10 Feb 2016 18:23:57 +1100
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Acked-by: Ian Munsie <imunsie@au1.ibm.com>

> +    /*
> +     * Look for the interrupt number.
> +     * On bare-metal, we know the range 0 only contains the PSL
> +     * interrupt so, we could start counting at range 1 and initialize
> +     * afu_irq at 1.
> +     * In a guest, range 0 also contains AFU interrupts, so it must
> +     * be counted for, but we initialize afu_irq at 0 to take into
> +     * account the PSL interrupt.
> +     *
> +     * For code-readability, it just seems easier to go over all
> +     * the ranges.
> +     */

Thanks for adding that explanation :)

> +    if (cpu_has_feature(CPU_FTR_HVMODE))
> +        alloc_count = count;
> +    else
> +        alloc_count = count + 1;

Almost a shame you can't reuse the afu_irq_range_start function you
defined for this, but doing so would probably make the code less
readable, so fine to leave this as is.

>      /* We've allocated all memory now, so let's do the irq allocations */
>      irq_name = list_first_entry(&ctx->irq_names, struct cxl_irq_name, list);
> -    for (r = 1; r < CXL_IRQ_RANGES; r++) {
> +    for (r = afu_irq_range_start(); r < CXL_IRQ_RANGES; r++) {
>          hwirq = ctx->irqs.offset[r];
>          for (i = 0; i < ctx->irqs.range[r]; hwirq++, i++) {
> -            cxl_map_irq(ctx->afu->adapter, hwirq,
> -                    cxl_irq_afu, ctx, irq_name->name);
> +            if (r == 0 && i == 0)
> +                /* PSL interrupt, only for guest */

That comment is perhaps not as clear as it could be - the interrupt is
used on either, but it's only allocated per context on PowerVM guests.

Cheers,
-Ian