irqchip/gic-v5: Allocate ITS parent LPIs as a range

The ITS MSI domain no longer manages LPI allocation directly. LPIs are
allocated and freed by the parent LPI domain, which can now handle a
full range of interrupts and unwind partial allocations internally.

Make the ITS domain request and release the parent IRQs as a single
range instead of iterating over each interrupt. The ITS allocation
path then only needs to reserve EventIDs, allocate the parent range,
and fill in the ITS irq_data for each MSI. Since no operation in the
per-MSI loop can fail, the partial parent-free unwind becomes
unnecessary.

On teardown, reset the ITS irq_data for the range and then release the
parent range in one call, leaving LPI teardown to the LPI domain.

Fixes: 0f01013 ("irqchip/gic-v5: Add GICv5 LPI/IPI support")
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260506093634.382062-4-sascha.bischoff@arm.com

Author: Sticklyman1936

drivers/irqchip/irq-gic-v5-its.c

@@ -937,6 +937,7 @@ static int gicv5_its_irq_domain_alloc(struct irq_domain *domain, unsigned int vi
 	int ret, i;
 
 	its_dev = info->scratchpad[0].ptr;
+	device_id = its_dev->device_id;
 
 	ret = gicv5_its_alloc_eventid(its_dev, info, nr_irqs, &event_id_base);
 	if (ret)
@@ -946,14 +947,11 @@ static int gicv5_its_irq_domain_alloc(struct irq_domain *domain, unsigned int vi
 	if (ret)
 		goto out_eventid;
 
-	device_id = its_dev->device_id;
+	ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, NULL);
+	if (ret)
+		goto out_eventid;
 
 	for (i = 0; i < nr_irqs; i++) {
-		ret = irq_domain_alloc_irqs_parent(domain, virq + i, 1, NULL);
-		if (ret) {
-			goto out_free_irqs;
-		}
-
 		/*
 		 * Store eventid and deviceid into the hwirq for later use.
 		 *
@@ -972,12 +970,6 @@ static int gicv5_its_irq_domain_alloc(struct irq_domain *domain, unsigned int vi
 
 	return 0;
 
-out_free_irqs:
-	while (--i >= 0) {
-		irqd = irq_domain_get_irq_data(domain, virq + i);
-		irq_domain_reset_irq_data(irqd);
-		irq_domain_free_irqs_parent(domain, virq + i, 1);
-	}
 out_eventid:
 	gicv5_its_free_eventid(its_dev, event_id_base, nr_irqs);
 	return ret;
@@ -1000,14 +992,14 @@ static void gicv5_its_irq_domain_free(struct irq_domain *domain, unsigned int vi
 	bitmap_release_region(its_dev->event_map, event_id_base,
 			      get_count_order(nr_irqs));
 
-	/*  Hierarchically free irq data */
 	for (i = 0; i < nr_irqs; i++) {
 		d = irq_domain_get_irq_data(domain, virq + i);
-
 		irq_domain_reset_irq_data(d);
-		irq_domain_free_irqs_parent(domain, virq + i, 1);
 	}
 
+	/*  Hierarchically free irq data */
+	irq_domain_free_irqs_parent(domain, virq, nr_irqs);
+
 	gicv5_its_syncr(its, its_dev);
 	gicv5_irs_syncr();
 }