Re: [Xen-devel] [PATCH v2 12/12] xen/domain: Allocate d->vcpu[] in domain_create()

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andrew,

On 08/15/2018 02:50 PM, Andrew Cooper wrote:
> On 15/08/18 14:17, Julien Grall wrote:
> > > > diff --git a/xen/arch/arm/vgic/vgic.c b/xen/arch/arm/vgic/vgic.c
> > > > index 832632a..4124817 100644
> > > > --- a/xen/arch/arm/vgic/vgic.c
> > > > +++ b/xen/arch/arm/vgic/vgic.c
> > > > @@ -951,27 +951,7 @@ void vgic_sync_hardware_irq(struct domain *d,
> > > >      unsigned int vgic_max_vcpus(const struct domain *d)
> > > >    {
> > > > -    unsigned int vgic_vcpu_limit;
> > > > -
> > > > -    switch ( d->arch.vgic.version )
> > > > -    {
> > > > -    case GIC_INVALID:
> > > > -        /*
> > > > -         * Since evtchn_init would call domain_max_vcpus for poll_mask
> > > > -         * allocation before the VGIC has been initialised, we need to
> > > > -         * return some safe value in this case. As this is for
> > > > allocation
> > > > -         * purposes, go with the maximum value.
> > > > -         */
> > > > -        vgic_vcpu_limit = MAX_VIRT_CPUS;
> > > > -        break;
> > > > -    case GIC_V2:
> > > > -        vgic_vcpu_limit = VGIC_V2_MAX_CPUS;
> > > > -        break;
> > > > -    default:
> > > > -        BUG();
> > > > -    }
> > > > -
> > > > -    return min_t(unsigned int, MAX_VIRT_CPUS, vgic_vcpu_limit);
> > > > +    return min_t(unsigned int, MAX_VIRT_CPUS,
> > > > d->arch.vgic.handler->max_vcpus);
> > > >    }
> > > Since both implementations are equal now, can you place this in vgic.h
> > > as a static inline function?
> > vgic/vgic.c is part of the new vGIC implementation (selectable at th e
> > compilation time) and using a different layout for the vgic_dist
> > structure. The structure is described in asm/new_vgic.h and does not
> > store the max vcpus anymore.
> >
> > Instead, the switch should be retained and only the case GIC_INVALID
> > should be dropped.
> What about GIC_V3?  VGIC_V3_MAX_CPUS seems to be 255 at the moment.
GICv3 is not yet supported by the new vGIC and disabled at compile time. 
So we should never reach this code with d->arch.vgic.version == GIC_V3.
Cheers,

--
Julien Grall

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