xen/arm: do not add a second irq to the LRs if one is already present

When the guest re-enable IRQs, do not add guest IRQs to LRs twice.

Suggested-by: Julien Grall <julien.grall@linaro.org>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

xen/arch/arm/vgic.c

@@ -370,7 +370,7 @@ static void vgic_enable_irqs(struct vcpu *v, uint32_t r, int n)
         irq = i + (32 * n);
         p = irq_to_pending(v, irq);
         set_bit(GIC_IRQ_GUEST_ENABLED, &p->status);
-        if ( !list_empty(&p->inflight) )
+        if ( !list_empty(&p->inflight) && !test_bit(GIC_IRQ_GUEST_VISIBLE, &p->status) )
             gic_set_guest_irq(v, irq, GICH_LR_PENDING, p->priority);
         i++;
     }