[PATCH 4.13 108/109] genirq/msi: Fix populating multiple interrupts

Greg Kroah-Hartman
2017-09-24T20:44:47Z

From: John Keeping <john@metanate.com>

commit 596a7a1d0989c621c3ae49be73a1d1f9de22eb5a upstream.

On allocating the interrupts routed via a wire-to-MSI bridge, the allocator
iterates over the MSI descriptors to build the hierarchy, but fails to use
the descriptor interrupt number, and instead uses the base number,
generating the wrong IRQ domain mappings.

The fix is to use the MSI descriptor interrupt number when setting up
the interrupt instead of the base interrupt for the allocation range.

The only saving grace is that although the MSI descriptors are allocated
in bulk, the wired interrupts are only allocated one by one (so
desc->irq == virq) and the bug went unnoticed so far.

Fixes: 2145ac9310b60 ("genirq/msi: Add msi_domain_populate_irqs")
Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/20170906103540.373864a2.john@metanate.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/irq/msi.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -315,11 +315,12 @@ int msi_domain_populate_irqs(struct irq_

ops->set_desc(arg, desc);
/* Assumes the domain mutex is held! */
- ret = irq_domain_alloc_irqs_hierarchy(domain, virq, 1, arg);
+ ret = irq_domain_alloc_irqs_hierarchy(domain, desc->irq, 1,
+ arg);
if (ret)
break;

- irq_set_msi_desc_off(virq, 0, desc);
+ irq_set_msi_desc_off(desc->irq, 0, desc);
}

if (ret) {