PCI/MSI: Fix MSI IRQ domains for VFs on virtual buses

SR-IOV creates a virtual bus where bus->self is NULL.  When we add VFs and
scan for an MSI domain, pci_set_bus_msi_domain() dereferences bus->self,
which causes a kernel NULL pointer dereference oops.

Scan up to the parent bus until we find a real bridge where we can get the
MSI domain.

[bhelgaas: changelog]
Fixes: 44aa0c657e3e ("PCI/MSI: Add hooks to populate the msi_domain field")
Tested-by: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index c8cc0e62a7b9d25733a45253fb051dac22f53dd2..8361d27e5ecad82ff9767c3d55a019a66f884046 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -676,15 +676,20 @@ static struct irq_domain *pci_host_bridge_msi_domain(struct pci_bus *bus)
 static void pci_set_bus_msi_domain(struct pci_bus *bus)
 {
        struct irq_domain *d;
+       struct pci_bus *b;
 
        /*
-        * Either bus is the root, and we must obtain it from the
-        * firmware, or we inherit it from the bridge device.
+        * The bus can be a root bus, a subordinate bus, or a virtual bus
+        * created by an SR-IOV device.  Walk up to the first bridge device
+        * found or derive the domain from the host bridge.
         */
-       if (pci_is_root_bus(bus))
-               d = pci_host_bridge_msi_domain(bus);
-       else
-               d = dev_get_msi_domain(&bus->self->dev);
+       for (b = bus, d = NULL; !d && !pci_is_root_bus(b); b = b->parent) {
+               if (b->self)
+                       d = dev_get_msi_domain(&b->self->dev);
+       }
+
+       if (!d)
+               d = pci_host_bridge_msi_domain(b);
 
        dev_set_msi_domain(&bus->dev, d);
 }