[tip:irq/core] x86/apic: Mark single target interrupts

From: tip-bot for Thomas Gleixner
Date: Thu Jun 22 2017 - 13:15:02 EST

Commit-ID: 3ca57222c36ba31b80aa25de313f3c8ab26a8102
Gitweb: http://git.kernel.org/tip/3ca57222c36ba31b80aa25de313f3c8ab26a8102
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Tue, 20 Jun 2017 01:37:54 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 22 Jun 2017 18:21:26 +0200

x86/apic: Mark single target interrupts

If the interrupt destination mode of the APIC is physical then the
effective affinity is restricted to a single CPU.

Mark the interrupt accordingly in the domain allocation code, so the core
code can avoid pointless affinity setting attempts.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Link: http://lkml.kernel.org/r/20170619235447.508846202@xxxxxxxxxxxxx

arch/x86/kernel/apic/vector.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index b270a76..2567dc0 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -371,6 +371,13 @@ static int x86_vector_alloc_irqs(struct irq_domain *domain, unsigned int virq,
if (err)
goto error;
+ /*
+ * If the apic destination mode is physical, then the
+ * effective affinity is restricted to a single target
+ * CPU. Mark the interrupt accordingly.
+ */
+ if (!apic->irq_dest_mode)
+ irqd_set_single_target(irq_data);

return 0;