[PATCH] PCI/MSI: Fix MSI IRQ domains for SR-IOV

From: Alex Williamson
Date: Fri Sep 18 2015 - 17:08:59 EST


SR-IOV creates a virtual bus where bus->self is NULL. This results
in a segfault as VFs are added and we scan for an MSI domain without
taking that into account. Detect this and scan up to the parent bus
until we find a real bridge.

Fixes: 44aa0c657e3e ("PCI/MSI: Add hooks to populate the msi_domain field")
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
drivers/pci/probe.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 0b2be17..b42419e 100644
--- 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);
}

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