[PATCH 1/3] irqchip/gic-v5: Move LPI alloc/free into LPI domain

Sascha Bischoff
2026-04-30T15:35:37Z

Rather than relying on the domains built on top of GICv5's LPI domain
to manage LPI allocations and frees, move that into the LPI domain
itself. This, rightly, ensures that domains other than the LPI itself
have no knowledge of LPI allocations themselves. This not only cleans
up the LPI domain itself, but also the IPI and ITS MSI domains which
build upon it.

While we're at it, drop the helpers wrapping the helpers -
gicv5_alloc_lpi() and gicv5_free_lpi() - and directly use alloc_lpi()
and release_lpi() instead.

Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
---
drivers/irqchip/irq-gic-v5-its.c | 14 ++------
drivers/irqchip/irq-gic-v5.c | 54 +++++++++++++++---------------
include/linux/irqchip/arm-gic-v5.h | 3 --
3 files changed, 29 insertions(+), 42 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v5-its.c b/drivers/irqchip/irq-gic-v5-its.c
index 36a8d1368f0e4..36d03f82ef684 100644
--- a/drivers/irqchip/irq-gic-v5-its.c
+++ b/drivers/irqchip/irq-gic-v5-its.c
@@ -929,8 +929,8 @@ static void gicv5_its_free_eventid(struct gicv5_its_dev *its_dev, u32 event_id_b
static int gicv5_its_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
unsigned int nr_irqs, void *arg)
{
- u32 device_id, event_id_base, lpi;
struct gicv5_its_dev *its_dev;
+ u32 device_id, event_id_base;
msi_alloc_info_t *info = arg;
irq_hw_number_t hwirq;
struct irq_data *irqd;
@@ -949,16 +949,8 @@ static int gicv5_its_irq_domain_alloc(struct irq_domain *domain, unsigned int vi
device_id = its_dev->device_id;

for (i = 0; i < nr_irqs; i++) {
- ret = gicv5_alloc_lpi();
- if (ret < 0) {
- pr_debug("Failed to find free LPI!\n");
- goto out_free_irqs;
- }
- lpi = ret;
-
- ret = irq_domain_alloc_irqs_parent(domain, virq + i, 1, &lpi);
+ ret = irq_domain_alloc_irqs_parent(domain, virq + i, 1, NULL);
if (ret) {
- gicv5_free_lpi(lpi);
goto out_free_irqs;
}

@@ -983,7 +975,6 @@ static int gicv5_its_irq_domain_alloc(struct irq_domain *domain, unsigned int vi
out_free_irqs:
while (--i >= 0) {
irqd = irq_domain_get_irq_data(domain, virq + i);
- gicv5_free_lpi(irqd->parent_data->hwirq);
irq_domain_reset_irq_data(irqd);
irq_domain_free_irqs_parent(domain, virq + i, 1);
}
@@ -1013,7 +1004,6 @@ static void gicv5_its_irq_domain_free(struct irq_domain *domain, unsigned int vi
for (i = 0; i < nr_irqs; i++) {
d = irq_domain_get_irq_data(domain, virq + i);

- gicv5_free_lpi(d->parent_data->hwirq);
irq_domain_reset_irq_data(d);
irq_domain_free_irqs_parent(domain, virq + i, 1);
}
diff --git a/drivers/irqchip/irq-gic-v5.c b/drivers/irqchip/irq-gic-v5.c
index 6b0903be8ebfd..a3c9eaa8ff486 100644
--- a/drivers/irqchip/irq-gic-v5.c
+++ b/drivers/irqchip/irq-gic-v5.c
@@ -59,16 +59,6 @@ static void release_lpi(u32 lpi)
ida_free(&lpi_ida, lpi);
}

-int gicv5_alloc_lpi(void)
-{
- return alloc_lpi();
-}
-
-void gicv5_free_lpi(u32 lpi)
-{
- release_lpi(lpi);
-}
-
static void gicv5_ppi_priority_init(void)
{
write_sysreg_s(REPEAT_BYTE(GICV5_IRQ_PRI_MI), SYS_ICC_PPI_PRIORITYR0_EL1);
@@ -806,18 +796,37 @@ static void gicv5_lpi_config_reset(struct irq_data *d)
gicv5_lpi_irq_write_pending_state(d, false);
}

+static void gicv5_irq_lpi_domain_free(struct irq_domain *domain, unsigned int virq,
+ unsigned int nr_irqs)
+{
+ struct irq_data *d;
+
+ if (WARN_ON_ONCE(nr_irqs != 1))
+ return;
+
+ d = irq_domain_get_irq_data(domain, virq);
+
+
+ release_lpi(d->hwirq);
+
+ irq_set_handler(virq, NULL);
+ irq_domain_reset_irq_data(d);
+}
+
static int gicv5_irq_lpi_domain_alloc(struct irq_domain *domain, unsigned int virq,
unsigned int nr_irqs, void *arg)
{
irq_hw_number_t hwirq;
struct irq_data *irqd;
- u32 *lpi = arg;
int ret;

if (WARN_ON_ONCE(nr_irqs != 1))
return -EINVAL;

- hwirq = *lpi;
+ ret = alloc_lpi();
+ if (ret < 0)
+ return ret;
+ hwirq = ret;

irqd = irq_domain_get_irq_data(domain, virq);

@@ -826,8 +835,10 @@ static int gicv5_irq_lpi_domain_alloc(struct irq_domain *domain, unsigned int vi
irqd_set_single_target(irqd);

ret = gicv5_irs_iste_alloc(hwirq);
- if (ret < 0)
+ if (ret < 0) {
+ release_lpi(hwirq);
return ret;
+ }

gicv5_hwirq_init(hwirq, GICV5_IRQ_PRI_MI, GICV5_HWIRQ_TYPE_LPI);
gicv5_lpi_config_reset(irqd);
@@ -837,7 +848,7 @@ static int gicv5_irq_lpi_domain_alloc(struct irq_domain *domain, unsigned int vi

static const struct irq_domain_ops gicv5_irq_lpi_domain_ops = {
.alloc = gicv5_irq_lpi_domain_alloc,
- .free = gicv5_irq_domain_free,
+ .free = gicv5_irq_lpi_domain_free,
};

void __init gicv5_init_lpi_domain(void)
@@ -859,21 +870,12 @@ static int gicv5_irq_ipi_domain_alloc(struct irq_domain *domain, unsigned int vi
{
struct irq_data *irqd;
int ret, i;
- u32 lpi;

for (i = 0; i < nr_irqs; i++) {
- ret = gicv5_alloc_lpi();
- if (ret < 0)
+ ret = irq_domain_alloc_irqs_parent(domain, virq + i, 1, NULL);
+ if (ret)
return ret;

- lpi = ret;
-
- ret = irq_domain_alloc_irqs_parent(domain, virq + i, 1, &lpi);
- if (ret) {
- gicv5_free_lpi(lpi);
- return ret;
- }
-
irqd = irq_domain_get_irq_data(domain, virq + i);

irq_domain_set_hwirq_and_chip(domain, virq + i, i,
@@ -899,8 +901,6 @@ static void gicv5_irq_ipi_domain_free(struct irq_domain *domain, unsigned int vi
if (!d)
return;

- gicv5_free_lpi(d->parent_data->hwirq);
-
irq_set_handler(virq + i, NULL);
irq_domain_reset_irq_data(d);
irq_domain_free_irqs_parent(domain, virq + i, 1);
diff --git a/include/linux/irqchip/arm-gic-v5.h b/include/linux/irqchip/arm-gic-v5.h
index 40d2fce682940..f78787e654f4c 100644
--- a/include/linux/irqchip/arm-gic-v5.h
+++ b/include/linux/irqchip/arm-gic-v5.h
@@ -425,9 +425,6 @@ struct gicv5_its_itt_cfg {
void gicv5_init_lpis(u32 max);
void gicv5_deinit_lpis(void);

-int gicv5_alloc_lpi(void);
-void gicv5_free_lpi(u32 lpi);
-
void __init gicv5_its_of_probe(struct device_node *parent);
void __init gicv5_its_acpi_probe(void);
#endif
--
2.34.1