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    Subject[PATCH v3 2/2] powerpc/pseries: pass MSI affinity to irq_create_mapping()
    Date
    With virtio multiqueue, normally each queue IRQ is mapped to a CPU.

    But since commit 0d9f0a52c8b9f ("virtio_scsi: use virtio IRQ affinity")
    this is broken on pseries.

    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.

    As the previous patch has added the affinity parameter to
    irq_create_mapping() we can forward the affinity from rtas_setup_msi_irqs()
    to irq_domain_alloc_descs().

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

    BugId: https://bugzilla.redhat.com/show_bug.cgi?id=1702939
    Signed-off-by: Laurent Vivier <lvivier@redhat.com>
    Reviewed-by: Greg Kurz <groug@kaod.org>
    ---
    arch/powerpc/platforms/pseries/msi.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    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);
    --
    2.28.0
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