From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@linaro.org>
Subject: Re: [PATCH v2 08/21] xen/arm: Initialize the virtual
 GIC later
Date: Fri, 29 Aug 2014 16:04:28 -0400
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To: Andrii Tseglytskyi <andrii.tseglytskyi@globallogic.com>
Cc: Ian Campbell <ian.campbell@citrix.com>, Tim Deegan <tim@xen.org>, Ian Jackson <ian.jackson@eu.citrix.com>, Stefano Stabellini <stefano.stabellini@citrix.com>, Jan Beulich <jbeulich@suse.com>, xen-devel <xen-devel@lists.xenproject.org>, Daniel De Graaf <dgdegra@tycho.nsa.gov>
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On 29/08/14 15:49, Andrii Tseglytskyi wrote:
> On Fri, Aug 29, 2014 at 9:57 PM, Julien Grall <julien.grall@linaro.org> wrote:
>> You will have to modify the function for your purpose. If you plan to PIRQ
>> == VIRQ every time, you could do smth like:
>>
>>
>> d->arch.vgic.nr_spis = gic_number_lines() - 32;
>>
>> I assume, you already modified vgic_allocate_irq to return directly the
>> pirq, and do nothing in vgic_free_irq.
>
> Yes, locally I did the same as you mentioned, but I'm thinking about
> solution which will allow me to have 1 to 1 irq mapping and which will
> be acceptable for Xen mainline.

IHMO, the best solution would adding a boolean in the new DOMCTL to 
specify if we want to use PIRQ == VIRQ or not.

Then you will have to modify vgic_allocate_irq to return the physical 
IRQ if the domain as this new option enabled.

> My local diff is:
>
> diff --git a/xen/arch/arm/physdev.c b/xen/arch/arm/physdev.c
> index 9333aa0..50ff100 100644
> --- a/xen/arch/arm/physdev.c
> +++ b/xen/arch/arm/physdev.c
> @@ -46,16 +46,13 @@ static int physdev_map_pirq(domid_t domid, int
> type, int index, int *pirq_p)
>
>       virq = vgic_allocate_virq(d, irq);
>       ret = -EMFILE;
>       if ( virq == -1 )
>           goto free_domain;
>
> -    ret = route_irq_to_guest(d, virq, irq, "routed IRQ");
> +    ret = route_irq_to_guest(d, irq, irq, "routed IRQ");

With this change you may have some issue when unmap_pirq is used. I 
would modify vgic_allocate_irq to always return the physical IRQ number.

The code will be also more clean.

-- 
Julien Grall