[Qemu-devel] [PATCH V2 1/4] hw/pxb: remove the built-in pci bridge

[Marcel Apfelbaum <marcel@redhat.com>]

As part of porting the pxb device to Q35 remove the internal pci-2-pci
bridge. The only way to hot-pug devices on the extra PCI root buses
is by adding a pci-2-pci to the pxb before the firmware assign the
IO/mem resources.

Keep the internal bridge for existing machines.

Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
---
 hw/pci-bridge/pci_expander_bridge.c | 27 +++++++++++++++++++--------
 include/hw/compat.h                 |  4 ++++
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/hw/pci-bridge/pci_expander_bridge.c b/hw/pci-bridge/pci_expander_bridge.c
index 57f8a37..541414c 100644
--- a/hw/pci-bridge/pci_expander_bridge.c
+++ b/hw/pci-bridge/pci_expander_bridge.c
@@ -34,6 +34,9 @@ typedef struct PXBBus {
 #define TYPE_PXB_DEVICE "pxb"
 #define PXB_DEV(obj) OBJECT_CHECK(PXBDev, (obj), TYPE_PXB_DEVICE)
 
+#define PXB_FLAG_ENABLE_BRIDGE_BIT 0
+#define PXB_FLAG_ENABLE_BRIDGE (1 << PXB_FLAG_ENABLE_BRIDGE_BIT)
+
 typedef struct PXBDev {
     /*< private >*/
     PCIDevice parent_obj;
@@ -41,6 +44,7 @@ typedef struct PXBDev {
 
     uint8_t bus_nr;
     uint16_t numa_node;
+    uint32_t flags;
 } PXBDev;
 
 static GList *pxb_dev_list;
@@ -196,7 +200,7 @@ static gint pxb_compare(gconstpointer a, gconstpointer b)
 static int pxb_dev_initfn(PCIDevice *dev)
 {
     PXBDev *pxb = PXB_DEV(dev);
-    DeviceState *ds, *bds;
+    DeviceState *ds, *bds = NULL;
     PCIBus *bus;
     const char *dev_name = NULL;
 
@@ -211,18 +215,21 @@ static int pxb_dev_initfn(PCIDevice *dev)
     }
 
     ds = qdev_create(NULL, TYPE_PXB_HOST);
-    bus = pci_bus_new(ds, "pxb-internal", NULL, NULL, 0, TYPE_PXB_BUS);
+    if (pxb->flags & PXB_FLAG_ENABLE_BRIDGE) {
+        bus = pci_bus_new(ds, "pxb-internal", NULL, NULL, 0, TYPE_PXB_BUS);
+        bds = qdev_create(BUS(bus), "pci-bridge");
+        bds->id = dev_name;
+        qdev_prop_set_uint8(bds, PCI_BRIDGE_DEV_PROP_CHASSIS_NR, pxb->bus_nr);
+        qdev_prop_set_bit(bds, PCI_BRIDGE_DEV_PROP_SHPC, false);
+    } else {
+        bus = pci_bus_new(ds, dev_name, NULL, NULL, 0, TYPE_PXB_BUS);
+    }
 
     bus->parent_dev = dev;
     bus->address_space_mem = dev->bus->address_space_mem;
     bus->address_space_io = dev->bus->address_space_io;
     bus->map_irq = pxb_map_irq_fn;
 
-    bds = qdev_create(BUS(bus), "pci-bridge");
-    bds->id = dev_name;
-    qdev_prop_set_uint8(bds, PCI_BRIDGE_DEV_PROP_CHASSIS_NR, pxb->bus_nr);
-    qdev_prop_set_bit(bds, PCI_BRIDGE_DEV_PROP_SHPC, false);
-
     PCI_HOST_BRIDGE(ds)->bus = bus;
 
     if (pxb_register_bus(dev, bus)) {
@@ -230,7 +237,9 @@ static int pxb_dev_initfn(PCIDevice *dev)
     }
 
     qdev_init_nofail(ds);
-    qdev_init_nofail(bds);
+    if (bds) {
+        qdev_init_nofail(bds);
+    }
 
     pci_word_test_and_set_mask(dev->config + PCI_STATUS,
                                PCI_STATUS_66MHZ | PCI_STATUS_FAST_BACK);
@@ -251,6 +260,8 @@ static Property pxb_dev_properties[] = {
     /* Note: 0 is not a legal a PXB bus number. */
     DEFINE_PROP_UINT8("bus_nr", PXBDev, bus_nr, 0),
     DEFINE_PROP_UINT16("numa_node", PXBDev, numa_node, NUMA_NODE_UNASSIGNED),
+    DEFINE_PROP_BIT("x-enable-internal-bridge", PXBDev, flags,
+                    PXB_FLAG_ENABLE_BRIDGE_BIT, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/include/hw/compat.h b/include/hw/compat.h
index 97feb75..cbf65ee 100644
--- a/include/hw/compat.h
+++ b/include/hw/compat.h
@@ -10,6 +10,10 @@
             .driver   = "virtio-pci",\
             .property = "disable-pcie",\
             .value    = "on",\
+        },{\
+            .driver   = "pxb",\
+            .property = "x-enable-internal-bridge",\
+            .value    = "on",\
         },
 
 #define HW_COMPAT_2_3 \
-- 
2.1.0