From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 13 Sep 2017 21:29:54 +0000 (+0200)
Subject: x86/vector: Respect affinity mask in irq descriptor
X-Git-Tag: v4.15-rc1~149^2~10
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=d6ffc6ac83b1f9f12652d89b9cb5bcbfbea7796c;p=linux.git

x86/vector: Respect affinity mask in irq descriptor

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@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Yu Chen <yu.c.chen@intel.com>
Acked-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Len Brown <lenb@kernel.org>
Link: https://lkml.kernel.org/r/20170913213156.431670325@linutronix.de
---

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 14b21ca4483c..6789e286def9 100644
--- 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_data *irqd, const struct cpumask *dest)
 
 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);
 }