xen/pciback: Don't setup an fake IRQ handler for SR-IOV devices.

If we try to setup an fake IRQ handler for legacy interrupts
for devices that only have MSI-X (most if not all SR-IOV cards),
we will fail with this:

pciback[0000:01:10.0]: failed to install fake IRQ handler for IRQ 0! (rc:-38)

Since those cards don't have anything in dev->irq.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index 6c398fde7a83..28a2a5584831 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -48,6 +48,13 @@ void pciback_control_isr(struct pci_dev *dev, int reset)
         if (enable)
                 dev_data->irq = dev->irq;
 
+        /*
+         * SR-IOV devices in all use MSI-X and have no legacy
+         * interrupts, so inhibit creating a fake IRQ handler for them.
+         */
+        if (dev_data->irq == 0)
+                goto out;
+
         dev_dbg(&dev->dev, "%s: #%d %s %s%s %s-> %s\n",
                 dev_data->irq_name,
                 dev_data->irq,