pci: replace the magic, 256, for the maximum of devfn

Introduce symbol PCI_SLOT_MAX for the # of slots,
and replace the magic, 256.
Signed-off-by: NIsaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/pci.h

@@ -16,6 +16,7 @@
 #define PCI_DEVFN(slot, func)   ((((slot) & 0x1f) << 3) | ((func) & 0x07))
 #define PCI_SLOT(devfn)         (((devfn) >> 3) & 0x1f)
 #define PCI_FUNC(devfn)         ((devfn) & 0x07)
+#define PCI_SLOT_MAX            32
 #define PCI_FUNC_MAX            8
 
 /* Class, Vendor and Device IDs from Linux's pci_ids.h */

hw/pci_internals.h

@@ -22,7 +22,7 @@ struct PCIBus {
     pci_hotplug_fn hotplug;
     DeviceState *hotplug_qdev;
     void *irq_opaque;
-    PCIDevice *devices[256];
+    PCIDevice *devices[PCI_SLOT_MAX * PCI_FUNC_MAX];
     PCIDevice *parent_dev;
     target_phys_addr_t mem_base;