pci: Allow PCI bus subtypes to support extended config space accesses

Some PHB implementations, eg. PAPR used on pseries machine, act like
a regular PCI bus rather than a PCIe bus, but allow access to the
PCIe extended config space anyway.

Introduce a new PCI bus class method to modelize this behaviour and
use it when adjusting the config space size limit during accesses.

No behaviour change for existing PCI bus types.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <155414130271.574858.4253514266378127489.stgit@bahia.lan>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/pci/pci.c

@@ -147,6 +147,11 @@ static uint16_t pcibus_numa_node(PCIBus *bus)
     return NUMA_NODE_UNASSIGNED;
 }
 
+static bool pcibus_allows_extended_config_space(PCIBus *bus)
+{
+    return false;
+}
+
 static void pci_bus_class_init(ObjectClass *klass, void *data)
 {
     BusClass *k = BUS_CLASS(klass);
@@ -162,6 +167,7 @@ static void pci_bus_class_init(ObjectClass *klass, void *data)
     pbc->is_root = pcibus_is_root;
     pbc->bus_num = pcibus_num;
     pbc->numa_node = pcibus_numa_node;
+    pbc->allows_extended_config_space = pcibus_allows_extended_config_space;
 }
 
 static const TypeInfo pci_bus_info = {
@@ -182,9 +188,22 @@ static const TypeInfo conventional_pci_interface_info = {
     .parent        = TYPE_INTERFACE,
 };
 
+static bool pciebus_allows_extended_config_space(PCIBus *bus)
+{
+    return true;
+}
+
+static void pcie_bus_class_init(ObjectClass *klass, void *data)
+{
+    PCIBusClass *pbc = PCI_BUS_CLASS(klass);
+
+    pbc->allows_extended_config_space = pciebus_allows_extended_config_space;
+}
+
 static const TypeInfo pcie_bus_info = {
     .name = TYPE_PCIE_BUS,
     .parent = TYPE_PCI_BUS,
+    .class_init = pcie_bus_class_init,
 };
 
 static PCIBus *pci_find_bus_nr(PCIBus *bus, int bus_num);
@@ -401,6 +420,11 @@ bool pci_bus_is_root(PCIBus *bus)
     return PCI_BUS_GET_CLASS(bus)->is_root(bus);
 }
 
+bool pci_bus_allows_extended_config_space(PCIBus *bus)
+{
+    return PCI_BUS_GET_CLASS(bus)->allows_extended_config_space(bus);
+}
+
 void pci_root_bus_new_inplace(PCIBus *bus, size_t bus_size, DeviceState *parent,
                               const char *name,
                               MemoryRegion *address_space_mem,

hw/pci/pci_host.c

@@ -54,7 +54,7 @@ static inline PCIDevice *pci_dev_find_by_addr(PCIBus *bus, uint32_t addr)
 static void pci_adjust_config_limit(PCIBus *bus, uint32_t *limit)
 {
     if (*limit > PCI_CONFIG_SPACE_SIZE) {
-        if (!pci_bus_is_express(bus)) {
+        if (!pci_bus_allows_extended_config_space(bus)) {
             *limit = PCI_CONFIG_SPACE_SIZE;
             return;
         }

include/hw/pci/pci.h

@@ -396,6 +396,8 @@ typedef PCIINTxRoute (*pci_route_irq_fn)(void *opaque, int pin);
 
 bool pci_bus_is_express(PCIBus *bus);
 bool pci_bus_is_root(PCIBus *bus);
+bool pci_bus_allows_extended_config_space(PCIBus *bus);
+
 void pci_root_bus_new_inplace(PCIBus *bus, size_t bus_size, DeviceState *parent,
                               const char *name,
                               MemoryRegion *address_space_mem,

include/hw/pci/pci_bus.h

@@ -18,6 +18,7 @@ typedef struct PCIBusClass {
     bool (*is_root)(PCIBus *bus);
     int (*bus_num)(PCIBus *bus);
     uint16_t (*numa_node)(PCIBus *bus);
+    bool (*allows_extended_config_space)(PCIBus *bus);
 } PCIBusClass;
 
 struct PCIBus {