From 93c8ca997409a5a217f4f64b83c4e0e5df451a7c Mon Sep 17 00:00:00 2001
From: Erik Skultety <eskultet@redhat.com>
Date: Thu, 15 Jan 2015 14:14:17 +0100
Subject: [PATCH] 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
---
 src/qemu/qemu_command.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index a2fcb649b3..8091fb3d45 100644
--- 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];