[patch 52/52] x86/vector: Respect affinity mask in irq descriptor

[Thomas Gleixner]

The interrupt descriptor has a preset affinity mask at allocation
time, which is usually the default affinity mask.

The current code does not respect that mask and places the vector at some
random CPU, which gets corrected later by a set_affinity() call. That's
silly because the vector allocation can respect the mask upfront and place
the interrupt on a CPU which is in the mask. If that fails, then the
affinity is broken and a interrupt assigned on any online CPU.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 arch/x86/kernel/apic/vector.c |   21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -249,12 +249,25 @@ static int assign_irq_vector(struct irq_
 
 static int assign_irq_vector_any_locked(struct irq_data *irqd)
 {
+	/* Get the affinity mask - either irq_default_affinity or (user) set */
+	const struct cpumask *affmsk = irq_data_get_affinity_mask(irqd);
 	int node = irq_data_get_node(irqd);
 
-	if (node != NUMA_NO_NODE) {
-		if (!assign_vector_locked(irqd, cpumask_of_node(node)))
-			return 0;
-	}
+	if (node == NUMA_NO_NODE)
+		goto all;
+	/* Try the intersection of @affmsk and node mask */
+	cpumask_and(vector_searchmask, cpumask_of_node(node), affmsk);
+	if (!assign_vector_locked(irqd, vector_searchmask))
+		return 0;
+	/* Try the node mask */
+	if (!assign_vector_locked(irqd, cpumask_of_node(node)))
+		return 0;
+all:
+	/* Try the full affinity mask */
+	cpumask_and(vector_searchmask, affmsk, cpu_online_mask);
+	if (!assign_vector_locked(irqd, vector_searchmask))
+		return 0;
+	/* Try the full online mask */
 	return assign_vector_locked(irqd, cpu_online_mask);
 }