[PATCH v2 2/4] irqchip/gic-v4: Unwind what its_alloc_vcpu_irqs() allocated on failure

[Fuad Tabba]

A failure in the its_alloc_vcpu_sgis() loop leaves behind both the SGI
domains created for the vPEs below the failing index and the vPE irqs
allocated before the loop, since irq_domain_remove() frees neither. Each
leaked vPE takes its ITS state with it, a vpe_id and an LPI pending
table.

Free both from a second label before the existing unwind. With the
freed pointers now cleared, its_free_sgi_irqs() can skip a vPE with no
SGI domain and be reused there. The check has to precede the lookup:
irq_find_mapping(NULL, 0) falls back to irq_default_domain, and the
live irq it returns would then be freed.

Fixes: 6d31b6ff985d ("irqchip/gic-v4.1: Add VSGI allocation/teardown")
Signed-off-by: Fuad Tabba <fuad.tabba at linux.dev>
---
 drivers/irqchip/irq-gic-v4.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v4.c b/drivers/irqchip/irq-gic-v4.c
index 754839e409f88..f707a3cb281aa 100644
--- a/drivers/irqchip/irq-gic-v4.c
+++ b/drivers/irqchip/irq-gic-v4.c
@@ -159,6 +159,8 @@ static int its_alloc_vcpu_sgis(struct its_vpe *vpe, int idx)
 	return -ENOMEM;
 }
 
+static void its_free_sgi_irqs(struct its_vm *vm);
+
 int its_alloc_vcpu_irqs(struct its_vm *vm)
 {
 	int vpe_base_irq, i;
@@ -189,11 +191,14 @@ int its_alloc_vcpu_irqs(struct its_vm *vm)
 		vm->vpes[i]->irq = vpe_base_irq + i;
 		ret = its_alloc_vcpu_sgis(vm->vpes[i], i);
 		if (ret)
-			goto err;
+			goto err_free_irqs;
 	}
 
 	return 0;
 
+err_free_irqs:
+	its_free_sgi_irqs(vm);
+	irq_domain_free_irqs(vpe_base_irq, vm->nr_vpes);
 err:
 	if (vm->domain) {
 		irq_domain_remove(vm->domain);
@@ -215,8 +220,13 @@ static void its_free_sgi_irqs(struct its_vm *vm)
 		return;
 
 	for (i = 0; i < vm->nr_vpes; i++) {
-		unsigned int irq = irq_find_mapping(vm->vpes[i]->sgi_domain, 0);
+		unsigned int irq;
 
+		/* irq_find_mapping() falls back to the default domain on NULL. */
+		if (!vm->vpes[i]->sgi_domain)
+			continue;
+
+		irq = irq_find_mapping(vm->vpes[i]->sgi_domain, 0);
 		if (WARN_ON(!irq))
 			continue;
 
-- 
2.39.5