pci: add reserved slot check to do_pci_register_device()

Add a new slot_reserved_mask bitmask to PCIBus indicating whether or not each
PCI slot on the bus is reserved. Ensure that it is initialised to zero to
maintain the existing behaviour that all slots are available by default, and
add the additional check with appropriate error reporting to
do_pci_register_device().

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

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;