Re: [Xen-devel] [PATCH v11 06/34] ARM: vGIC: move irq_to_pending() calls under the VGIC VCPU lock

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 09/06/17 18:41, Andre Przywara wrote:
> @@ -285,6 +291,17 @@ void arch_move_irqs(struct vcpu *v)
>      struct vcpu *v_target;
>      int i;
>
> +    /*
> +     * We don't migrate LPIs at the moment.
> +     * If we ever do, we must make sure that the struct pending_irq does
> +     * not go away, as there is no lock preventing this here.
> +     * To ensure this, we check if the loop below ever touches LPIs.
> +     * In the moment vgic_num_irqs() just covers SPIs, as it's mostly used
> +     * for allocating the pending_irq and irq_desc array, in which LPIs
> +     * don't participate.
IHMO, this paragraph should also be added on top of the definition 
vgic_num_irqs.
> +     */
> +    ASSERT(!is_lpi(vgic_num_irqs(d) - 1));
> +
>      for ( i = 32; i < vgic_num_irqs(d); i++ )
>      {
>          v_target = vgic_get_target_vcpu(v, i);
> @@ -299,6 +316,7 @@ void vgic_disable_irqs(struct vcpu *v, uint32_t r, int n)
>  {
>      const unsigned long mask = r;
>      struct pending_irq *p;
> +    struct irq_desc *desc;
>      unsigned int irq;
>      unsigned long flags;
>      int i = 0;
> @@ -307,17 +325,19 @@ void vgic_disable_irqs(struct vcpu *v, uint32_t r, int n)
>      while ( (i = find_next_bit(&mask, 32, i)) < 32 ) {
>          irq = i + (32 * n);
>          v_target = vgic_get_target_vcpu(v, irq);
> +
Spurious change.

>          spin_lock_irqsave(&v_target->arch.vgic.lock, flags);
>          p = irq_to_pending(v_target, irq);
>          clear_bit(GIC_IRQ_GUEST_ENABLED, &p->status);
>          gic_remove_from_lr_pending(v_target, p);
> +        desc = p->desc;
>          spin_unlock_irqrestore(&v_target->arch.vgic.lock, flags);
Cheers,

--
Julien Grall

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