https://lists.gnu.org/archive/html/qemu-devel/2014-08/msg03338.html
--- hw/acpi/pcihp.c.orig	2014-08-27 12:53:38.200621592 +0000
+++ hw/acpi/pcihp.c	2014-08-27 12:53:58.390518561 +0000
@@ -231,7 +231,7 @@
     uint32_t val = 0;
     int bsel = s->hotplug_select;
 
-    if (bsel < 0 || bsel > ACPI_PCIHP_MAX_HOTPLUG_BUS) {
+    if (bsel < 0 || bsel >= ACPI_PCIHP_MAX_HOTPLUG_BUS) {
         return 0;
     }