2 files changed, 16 insertions, 3 deletions

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 002e66920c..21e203b056 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -373,6 +373,7 @@ static void pci_bus_init(PCIBus *bus, DeviceState *parent,
 {
     assert(PCI_FUNC(devfn_min) == 0);
     bus->devfn_min = devfn_min;
+    bus->slot_reserved_mask = 0x0;
     bus->address_space_mem = address_space_mem;
     bus->address_space_io = address_space_io;
 
@@ -958,6 +959,11 @@ static bool pci_bus_devfn_available(PCIBus *bus, int devfn)
     return !(bus->devices[devfn]);
 }
 
+static bool pci_bus_devfn_reserved(PCIBus *bus, int devfn)
+{
+    return bus->slot_reserved_mask & (1UL << PCI_SLOT(devfn));
+}
+
 /* -1 for devfn means auto assign */
 static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
                                          const char *name, int devfn,
@@ -981,14 +987,20 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev, PCIBus *bus,
     if (devfn < 0) {
         for(devfn = bus->devfn_min ; devfn < ARRAY_SIZE(bus->devices);
             devfn += PCI_FUNC_MAX) {
-            if (pci_bus_devfn_available(bus, devfn)) {
+            if (pci_bus_devfn_available(bus, devfn) &&
+                   !pci_bus_devfn_reserved(bus, devfn)) {
                 goto found;
             }
         }
-        error_setg(errp, "PCI: no slot/function available for %s, all in use",
-                   name);
+        error_setg(errp, "PCI: no slot/function available for %s, all in use "
+                   "or reserved", name);
         return NULL;
     found: ;
+    } else if (pci_bus_devfn_reserved(bus, devfn)) {
+        error_setg(errp, "PCI: slot %d function %d not available for %s,"
+                   " reserved",
+                   PCI_SLOT(devfn), PCI_FUNC(devfn), name);
+        return NULL;
     } else if (!pci_bus_devfn_available(bus, devfn)) {
         error_setg(errp, "PCI: slot %d function %d not available for %s,"
                    " in use by %s",
diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
index 5484a9b5c5..bc34fd0017 100644
--- a/include/hw/pci/pci_bus.h
+++ b/include/hw/pci/pci_bus.h
@@ -23,6 +23,7 @@ struct PCIBus {
     PCIIOMMUFunc iommu_fn;
     void *iommu_opaque;
     uint8_t devfn_min;
+    uint32_t slot_reserved_mask;
     pci_set_irq_fn set_irq;
     pci_map_irq_fn map_irq;
     pci_route_irq_fn route_intx_to_irq;