Re: [Xen-devel] [PATCH v2 42/45] ARM: new VGIC: vgic-init: implement vgic_init

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 03/15/2018 08:30 PM, Andre Przywara wrote:
> +/* INIT/DESTROY */
> +
> +/**
> + * domain_vgic_init: initialize the dist data structures
> + * @d: domain pointer
> + * @nr_spis: number of SPIs
> + */
> +int domain_vgic_init(struct domain *d, unsigned int nr_spis)
> +{
> +    struct vgic_dist *dist = &d->arch.vgic;
> +    unsigned int i;
> +    int ret;
> +
> +    /* Limit the number of virtual SPIs supported to (1020 - 32) = 988  */
> +    if ( nr_spis > (1020 - NR_LOCAL_IRQS) )
> +        return -EINVAL;
> +    nr_spis = ROUNDUP(nr_spis, 32);
I think the roundup is misplaced. Here you might allow the guest to 
inject IRQs 1020-1023. From the Spec, using those values in the LRs for 
the vINTID field will result to unpredictable behavior.
So you want to move the ROUNDUP before the check. This will limit the 
SPI INT ID to 992, but this is not a big deal for now.

Cheers,

--
Julien Grall

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