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



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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