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 stable@vger.kernel.org.

thanks,

greg k-h

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

From 9ea69a55b3b9a71cded9726af591949c1138f235 Mon Sep 17 00:00:00 2001

From: Laurent Vivier lvivier@redhat.com 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.

Fixes: e75eafb9b039 ("genirq/msi: Switch to new irq spreading infrastructure") Signed-off-by: Laurent Vivier lvivier@redhat.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Greg Kurz groug@kaod.org Acked-by: Michael Ellerman mpe@ellerman.id.au Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20201126082852.1178497-3-lvivier@redhat.com

diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c index 133f6adcb39c..b3ac2455faad 100644 --- a/arch/powerpc/platforms/pseries/msi.c +++ b/arch/powerpc/platforms/pseries/msi.c @@ -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);