qemu: Tweak auto adding PCI bridge controller when extending default PCI bus

In case we find out, there are more PCI devices to be connected
than there are available slots on the default PCI bus, we automatically add a
new bus and a related PCI bridge controller as well. As there are no free slots
left on the default PCI bus, PCI bridge controller gets a free slot on a
newly created PCI bus which causes qemu to refuse to start the guest.
This fix introduces a new function qemuDomainPCIBusFullyReserved which
is checked right before we possibly try to reserve a slot for PCI bridge
controller.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1132900

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index a2fcb649b3e35d4d20d9d3c4e5c4cf66cd240c2a..8091fb3d456d9b336c7beaf7553034475e0ed548 100644 (file)
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1445,6 +1445,18 @@ qemuDomainSupportsPCI(virDomainDefPtr def)
     return false;
 }
 
+static bool
+qemuDomainPCIBusFullyReserved(virDomainPCIAddressBusPtr bus)
+{
+    size_t i;
+
+    for (i = bus->minSlot; i <= bus->maxSlot; i++)
+        if (!bus->slots[i])
+            return false;
+
+    return true;
+}
+
 int
 qemuDomainAssignPCIAddresses(virDomainDefPtr def,
                              virQEMUCapsPtr qemuCaps,
@@ -1479,9 +1491,15 @@ qemuDomainAssignPCIAddresses(virDomainDefPtr def,
                 goto cleanup;
             if (qemuAssignDevicePCISlots(def, qemuCaps, addrs) < 0)
                 goto cleanup;
-            /* Reserve 1 extra slot for a (potential) bridge */
-            if (virDomainPCIAddressReserveNextSlot(addrs, &info, flags) < 0)
-                goto cleanup;
+
+            for (i = 0; i < addrs->nbuses; i++) {
+                if (!qemuDomainPCIBusFullyReserved(&addrs->buses[i])) {
+
+                    /* Reserve 1 extra slot for a (potential) bridge */
+                    if (virDomainPCIAddressReserveNextSlot(addrs, &info, flags) < 0)
+                        goto cleanup;
+                }
+            }
 
             for (i = 1; i < addrs->nbuses; i++) {
                 virDomainPCIAddressBusPtr bus = &addrs->buses[i];