+
+#ifdef CONFIG_INTR_REMAP
+static void ir_irq_migration(struct work_struct *work);
+
+static DECLARE_DELAYED_WORK(ir_migration_work, ir_irq_migration);
+
+/*
+ * Migrate the IO-APIC irq in the presence of intr-remapping.
+ *
+ * For edge triggered, irq migration is a simple atomic update(of vector
+ * and cpu destination) of IRTE and flush the hardware cache.
+ *
+ * For level triggered, we need to modify the io-apic RTE aswell with the update
+ * vector information, along with modifying IRTE with vector and destination.
+ * So irq migration for level triggered is little bit more complex compared to
+ * edge triggered migration. But the good news is, we use the same algorithm
+ * for level triggered migration as we have today, only difference being,
+ * we now initiate the irq migration from process context instead of the
+ * interrupt context.
+ *
+ * In future, when we do a directed EOI (combined with cpu EOI broadcast
+ * suppression) to the IO-APIC, level triggered irq migration will also be
+ * as simple as edge triggered migration and we can do the irq migration
+ * with a simple atomic update to IO-APIC RTE.
+ */
+static void migrate_ioapic_irq(int irq, cpumask_t mask)
+{
+ struct irq_cfg *cfg = irq_cfg + irq;
+ struct irq_desc *desc = irq_desc + irq;
+ cpumask_t tmp, cleanup_mask;
+ struct irte irte;
+ int modify_ioapic_rte = desc->status & IRQ_LEVEL;
+ unsigned int dest;
+ unsigned long flags;
+
+ cpus_and(tmp, mask, cpu_online_map);
+ if (cpus_empty(tmp))
+ return;
+
+ if (get_irte(irq, &irte))
+ return;
+
+ if (assign_irq_vector(irq, mask))
+ return;
+
+ cpus_and(tmp, cfg->domain, mask);
+ dest = cpu_mask_to_apicid(tmp);
+
+ if (modify_ioapic_rte) {
+ spin_lock_irqsave(&ioapic_lock, flags);
+ __target_IO_APIC_irq(irq, dest, cfg->vector);
+ spin_unlock_irqrestore(&ioapic_lock, flags);
+ }
+
+ irte.vector = cfg->vector;
+ irte.dest_id = IRTE_DEST(dest);
+
+ /*
+ * Modified the IRTE and flushes the Interrupt entry cache.
+ */
+ modify_irte(irq, &irte);
+
+ if (cfg->move_in_progress) {
+ cpus_and(cleanup_mask, cfg->old_domain, cpu_online_map);
+ cfg->move_cleanup_count = cpus_weight(cleanup_mask);
+ send_IPI_mask(cleanup_mask, IRQ_MOVE_CLEANUP_VECTOR);
+ cfg->move_in_progress = 0;
+ }
+
+ irq_desc[irq].affinity = mask;
+}
+
+static int migrate_irq_remapped_level(int irq)
+{
+ int ret = -1;
+
+ mask_IO_APIC_irq(irq);
+
+ if (io_apic_level_ack_pending(irq)) {
+ /*
+ * Interrupt in progress. Migrating irq now will change the
+ * vector information in the IO-APIC RTE and that will confuse
+ * the EOI broadcast performed by cpu.
+ * So, delay the irq migration to the next instance.
+ */
+ schedule_delayed_work(&ir_migration_work, 1);
+ goto unmask;
+ }
+
+ /* everthing is clear. we have right of way */
+ migrate_ioapic_irq(irq, irq_desc[irq].pending_mask);
+
+ ret = 0;
+ irq_desc[irq].status &= ~IRQ_MOVE_PENDING;
+ cpus_clear(irq_desc[irq].pending_mask);
+
+unmask:
+ unmask_IO_APIC_irq(irq);
+ return ret;
+}
+
+static void ir_irq_migration(struct work_struct *work)
+{
+ int irq;
+
+ for (irq = 0; irq < NR_IRQS; irq++) {
+ struct irq_desc *desc = irq_desc + irq;
+ if (desc->status & IRQ_MOVE_PENDING) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&desc->lock, flags);
+ if (!desc->chip->set_affinity ||
+ !(desc->status & IRQ_MOVE_PENDING)) {
+ desc->status &= ~IRQ_MOVE_PENDING;
+ spin_unlock_irqrestore(&desc->lock, flags);
+ continue;
+ }
+
+ desc->chip->set_affinity(irq,
+ irq_desc[irq].pending_mask);
+ spin_unlock_irqrestore(&desc->lock, flags);
+ }
+ }
+}
+
+/*
+ * Migrates the IRQ destination in the process context.
+ */
+static void set_ir_ioapic_affinity_irq(unsigned int irq, cpumask_t mask)
+{
+ if (irq_desc[irq].status & IRQ_LEVEL) {
+ irq_desc[irq].status |= IRQ_MOVE_PENDING;
+ irq_desc[irq].pending_mask = mask;
+ migrate_irq_remapped_level(irq);
+ return;
+ }
+
+ migrate_ioapic_irq(irq, mask);
+}
+#endif
+