[PATCH 3/3] irqchip/gic-v5: Allocate ITS parent LPIs as a range

Sascha Bischoff
2026-04-30T15:36:17Z

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.

Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
---
drivers/irqchip/irq-gic-v5-its.c | 22 +++++++---------------
1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v5-its.c b/drivers/irqchip/irq-gic-v5-its.c
index 36d03f82ef684..28e39b065de0e 100644
--- a/drivers/irqchip/irq-gic-v5-its.c
+++ b/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();
}
--
2.34.1