FAILED: patch "[PATCH] powerpc/pseries: Pass MSI affinity to irq_create_mapping()" 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 9ea69a55b3b9a71cded9726af591949c1138f235 Mon Sep 17 00:00:00 2001
From: Laurent Vivier <[email protected]>
Date: Thu, 26 Nov 2020 09:28:52 +0100
Subject: [PATCH] powerpc/pseries: Pass MSI affinity to irq_create_mapping()

With virtio multiqueue, normally each queue IRQ is mapped to a CPU.

Commit 0d9f0a52c8b9f ("virtio_scsi: use virtio IRQ affinity") exposed an existing shortcoming of the arch code by moving virtio_scsi to the automatic IRQ affinity assignment.

The affinity is correctly computed in msi_desc but this is not applied to the system IRQs.

It appears the affinity is correctly passed to rtas_setup_msi_irqs() but lost at this point and never passed to irq_domain_alloc_descs() (see commit 06ee6d571f0e ("genirq: Add affinity hint to irq allocation")) because irq_create_mapping() doesn't take an affinity parameter.

Use the new irq_create_mapping_affinity() function, which allows to forward the affinity setting from rtas_setup_msi_irqs() to irq_domain_alloc_descs().

With this change, the virtqueues are correctly dispatched between the CPUs on pseries.

index 133f6adcb39c..b3ac2455faad 100644
@@ -458,7 +458,8 @@ static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
 			return hwirq;
 		}
 
-		virq = irq_create_mapping(NULL, hwirq);
+		virq = irq_create_mapping_affinity(NULL, hwirq,
+						   entry->affinity);
 
 		if (!virq) {
 			pr_debug("rtas_msi: Failed mapping hwirq %d\n", hwirq);