[PATCH 08/13] genirq: Add irq_domain_set_affinity()

[David Woodhouse <dwmw2@infradead.org>]

From: David Woodhouse <dwmw@amazon.co.uk>

This allows a maximal affinity to be set, for IRQ domains which cannot
target all CPUs in the system.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 include/linux/irqdomain.h |  4 ++++
 kernel/irq/irqdomain.c    | 28 ++++++++++++++++++++++++++--
 kernel/irq/manage.c       | 19 +++++++++++++++----
 3 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 6b5576da77f0..cf686f18c1fa 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -151,6 +151,7 @@ struct irq_domain_chip_generic;
  *      drivers using the generic chip library which uses this pointer.
  * @parent: Pointer to parent irq_domain to support hierarchy irq_domains
  * @debugfs_file: dentry for the domain debugfs file
+ * @max_affinity: mask of CPUs targetable by this IRQ domain
  *
  * Revmap data, used internally by irq_domain
  * @revmap_direct_max_irq: The largest hwirq that can be set for controllers that
@@ -177,6 +178,7 @@ struct irq_domain {
 #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
 	struct dentry		*debugfs_file;
 #endif
+	const struct cpumask *max_affinity;
 
 	/* reverse map data. The linear map gets appended to the irq_domain */
 	irq_hw_number_t hwirq_max;
@@ -453,6 +455,8 @@ extern void irq_domain_set_info(struct irq_domain *domain, unsigned int virq,
 				void *chip_data, irq_flow_handler_t handler,
 				void *handler_data, const char *handler_name);
 extern void irq_domain_reset_irq_data(struct irq_data *irq_data);
+extern int irq_domain_set_affinity(struct irq_domain *domain,
+				   const struct cpumask *affinity);
 #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
 extern struct irq_domain *irq_domain_create_hierarchy(struct irq_domain *parent,
 			unsigned int flags, unsigned int size,
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index ffd41f21afca..0b298355be1b 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -661,7 +661,7 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
 
 	/* Allocate a virtual interrupt number */
 	virq = irq_domain_alloc_descs(-1, 1, hwirq, of_node_to_nid(of_node),
-				      NULL, NULL);
+				      NULL, domain->max_affinity);
 	if (virq <= 0) {
 		pr_debug("-> virq allocation failed\n");
 		return 0;
@@ -1078,6 +1078,27 @@ void irq_domain_reset_irq_data(struct irq_data *irq_data)
 }
 EXPORT_SYMBOL_GPL(irq_domain_reset_irq_data);
 
+/**
+ * irq_domain_set_affinity - Set maximum CPU affinity for domain
+ * @parent:	Domain to set affinity for
+ * @affinity:	Pointer to cpumask, consumed by domain
+ *
+ * Sets the maximal set of CPUs to which interrupts in this domain may
+ * be delivered. Must only be called after creation, before any interrupts
+ * have been in the domain.
+ *
+ * This function retains a pointer to the cpumask which is passed in.
+ */
+int irq_domain_set_affinity(struct irq_domain *domain,
+			    const struct cpumask *affinity)
+{
+	if (cpumask_empty(affinity))
+		return -EINVAL;
+	domain->max_affinity = affinity;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_domain_set_affinity);
+
 #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
 /**
  * irq_domain_create_hierarchy - Add a irqdomain into the hierarchy
@@ -1110,6 +1131,9 @@ struct irq_domain *irq_domain_create_hierarchy(struct irq_domain *parent,
 	if (domain) {
 		domain->parent = parent;
 		domain->flags |= flags;
+		if (parent && parent->max_affinity)
+			irq_domain_set_affinity(domain,
+						parent->max_affinity);
 	}
 
 	return domain;
@@ -1375,7 +1399,7 @@ int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base,
 		virq = irq_base;
 	} else {
 		virq = irq_domain_alloc_descs(irq_base, nr_irqs, 0, node,
-					      affinity, NULL);
+					      affinity, domain->max_affinity);
 		if (virq < 0) {
 			pr_debug("cannot allocate IRQ(base %d, count %d)\n",
 				 irq_base, nr_irqs);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 5df903fccb60..e8c5f8ecd306 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -345,6 +345,10 @@ int irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask,
 	struct irq_desc *desc = irq_data_to_desc(data);
 	int ret = 0;
 
+	if (data->domain && data->domain->max_affinity &&
+	    !cpumask_subset(mask, data->domain->max_affinity))
+		return -EINVAL;
+
 	if (!chip || !chip->irq_set_affinity)
 		return -EINVAL;
 
@@ -484,13 +488,20 @@ int irq_setup_affinity(struct irq_desc *desc)
 	struct cpumask *set = irq_default_affinity;
 	int ret, node = irq_desc_get_node(desc);
 	static DEFINE_RAW_SPINLOCK(mask_lock);
-	static struct cpumask mask;
+	static struct cpumask mask, max_mask;
 
 	/* Excludes PER_CPU and NO_BALANCE interrupts */
 	if (!__irq_can_set_affinity(desc))
 		return 0;
 
 	raw_spin_lock(&mask_lock);
+
+	if (desc->irq_data.domain && desc->irq_data.domain->max_affinity)
+		cpumask_and(&max_mask, cpu_online_mask,
+			    desc->irq_data.domain->max_affinity);
+	else
+		cpumask_copy(&max_mask, cpu_online_mask);
+
 	/*
 	 * Preserve the managed affinity setting and a userspace affinity
 	 * setup, but make sure that one of the targets is online.
@@ -498,15 +509,15 @@ int irq_setup_affinity(struct irq_desc *desc)
 	if (irqd_affinity_is_managed(&desc->irq_data) ||
 	    irqd_has_set(&desc->irq_data, IRQD_AFFINITY_SET)) {
 		if (cpumask_intersects(desc->irq_common_data.affinity,
-				       cpu_online_mask))
+				       &max_mask))
 			set = desc->irq_common_data.affinity;
 		else
 			irqd_clear(&desc->irq_data, IRQD_AFFINITY_SET);
 	}
 
-	cpumask_and(&mask, cpu_online_mask, set);
+	cpumask_and(&mask, &max_mask, set);
 	if (cpumask_empty(&mask))
-		cpumask_copy(&mask, cpu_online_mask);
+		cpumask_copy(&mask, &max_mask);
 
 	if (node != NUMA_NO_NODE) {
 		const struct cpumask *nodemask = cpumask_of_node(node);
-- 
2.26.2