FAILED: patch "[PATCH] genirq/msi: Fix populating multiple interrupts" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: John Keeping <[email protected]>
Date: Wed, 6 Sep 2017 10:35:40 +0100
Subject: [PATCH] genirq/msi: Fix populating multiple interrupts

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.

index 48eadf416c24..3fa4bd59f569 100644
@@ -315,11 +315,12 @@ int msi_domain_populate_irqs(struct irq_domain *domain, struct device *dev,
 
 		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) {