Re: [Xen-devel] [PATCH 27/38] arm: split pending SPIs (global) out from pending PPIs and SGIs (per CPU)

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 1 Jun 2012, Ian Campbell wrote:
> This tracks SPIs in struct arch_domain and PPIs+SGIs in struct arch_vcpu which
> seems more logical.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
>  xen/arch/arm/vgic.c          |   17 ++++++++++-------
>  xen/include/asm-arm/domain.h |   10 ++++++++++
>  2 files changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
> index 629a0da..91d6166 100644
> --- a/xen/arch/arm/vgic.c
> +++ b/xen/arch/arm/vgic.c
> @@ -82,9 +82,8 @@ int domain_vgic_init(struct domain *d)
>      d->arch.vgic.shared_irqs =
>          xmalloc_array(struct vgic_irq_rank, DOMAIN_NR_RANKS(d));
>      d->arch.vgic.pending_irqs =
> -        xmalloc_array(struct pending_irq,
> -                d->arch.vgic.nr_lines + (32 * d->max_vcpus));
> -    for (i=0; i<d->arch.vgic.nr_lines + (32 * d->max_vcpus); i++)
> +        xzalloc_array(struct pending_irq, d->arch.vgic.nr_lines);
> +    for (i=0; i<d->arch.vgic.nr_lines; i++)
>          INIT_LIST_HEAD(&d->arch.vgic.pending_irqs[i].inflight);
>      for (i=0; i<DOMAIN_NR_RANKS(d); i++)
>          spin_lock_init(&d->arch.vgic.shared_irqs[i].lock);
> @@ -98,6 +97,10 @@ int vcpu_vgic_init(struct vcpu *v)
>  
>      spin_lock_init(&v->arch.vgic.private_irqs.lock);
>  
> +    memset(&v->arch.vgic.pending_irqs, 0, sizeof(v->arch.vgic.pending_irqs));
> +    for (i = 0; i < 32; i++)
> +        INIT_LIST_HEAD(&v->arch.vgic.pending_irqs[i].inflight);
> +
>      /* For SGI and PPI the target is always this CPU */
>      for ( i = 0 ; i < 8 ; i++ )
>          v->arch.vgic.private_irqs.itargets[i] =
> @@ -535,8 +538,7 @@ struct pending_irq *irq_to_pending(struct vcpu *v, 
> unsigned int irq)
>      /* Pending irqs allocation strategy: the first vgic.nr_lines irqs
>       * are used for SPIs; the rests are used for per cpu irqs */
>      if ( irq < 32 )
> -        n = &v->domain->arch.vgic.pending_irqs[irq + (v->vcpu_id * 32)
> -            + v->domain->arch.vgic.nr_lines];
> +        n = &v->arch.vgic.pending_irqs[irq];
>      else
>          n = &v->domain->arch.vgic.pending_irqs[irq - 32];
>      return n;
> @@ -548,6 +550,7 @@ void vgic_vcpu_inject_irq(struct vcpu *v, unsigned int 
> irq, int virtual)
>      uint8_t priority;
>      struct vgic_irq_rank *rank = vgic_irq_rank(v, 8, idx);
>      struct pending_irq *iter, *n = irq_to_pending(v, irq);
> +    unsigned long flags;
>  
>      /* irq still pending */
>      if (!list_empty(&n->inflight))
> @@ -564,7 +567,7 @@ void vgic_vcpu_inject_irq(struct vcpu *v, unsigned int 
> irq, int virtual)
>  
>      gic_set_guest_irq(irq, GICH_LR_PENDING, priority);
>  
> -    spin_lock(&v->arch.vgic.lock);
> +    spin_lock_irqsave(&v->arch.vgic.lock, flags);
>      list_for_each_entry ( iter, &v->arch.vgic.inflight_irqs, inflight )
>      {
>          if ( iter->priority > priority )
> @@ -575,7 +578,7 @@ void vgic_vcpu_inject_irq(struct vcpu *v, unsigned int 
> irq, int virtual)
>          }
>      }
>      list_add_tail(&n->inflight, &v->arch.vgic.inflight_irqs);
> -    spin_unlock(&v->arch.vgic.lock);
> +    spin_unlock_irqrestore(&v->arch.vgic.lock, flags);
>      /* we have a new higher priority irq, inject it into the guest */
>  }

Besides moving PPIs and SGIs to struct vcpu, this patch also turns
spin_lock into spin_lock_irqsave in vgic_vcpu_inject_irq: I think it is
correct because it can be called in IRQ context, but it needs to be
explicitly stated in the commit message.


> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 620b26e..32deb52 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -46,6 +46,10 @@ struct arch_domain
>          int ctlr;
>          int nr_lines;
>          struct vgic_irq_rank *shared_irqs;
> +        /*
> +         * SPIs are domain global, SGIs and PPIs are per-VCPU and stored in
> +         * struct arch_vcpu.
> +         */
>          struct pending_irq *pending_irqs;
>      } vgic;
>  
> @@ -114,7 +118,13 @@ struct arch_vcpu
>      uint32_t gic_lr[64];
>  
>      struct {
> +        /*
> +         * SGIs and PPIs are per-VCPU, SPIs are domain global and in
> +         * struct arch_domain.
> +         */
> +        struct pending_irq pending_irqs[32];
>          struct vgic_irq_rank private_irqs;
> +
>          /* This list is ordered by IRQ priority and it is used to keep
>           * track of the IRQs that the VGIC injected into the guest.
>           * Depending on the availability of LR registers, the IRQs might
> -- 
> 1.7.9.1
> 
> 
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> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel
> 

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