hw/pci: introduce PCI Expander Bridge (PXB)

PXB is a "light-weight" host bridge whose purpose is to enable
the main host bridge to support multiple PCI root buses
for pc machines.

As oposed to PCI-2-PCI bridge's secondary bus, PXB's bus
is a primary bus and can be associated with a NUMA node
(different from the main host bridge) allowing the guest OS
to recognize the proximity of a pass-through device to
other resources as RAM and CPUs.

The PXB is composed from:
 - A primary PCI bus (can be associated with a NUMA node)
   Acts like a normal pci bus and from the functionality point
   of view is an "expansion" of the bus behind the
   main host bridge.
 - A pci-2-pci bridge behind the primary PCI bus where the actual
   devices will be attached.
 - A host-bridge PCI device
   Situated on the bus behind the main host bridge, allows
   the BIOS to configure the bus number and IO/mem resources.
   It does not have its own config/data register for configuration
   cycles, this being handled by the main host bridge.
-  A host-bridge sysbus to comply with QEMU current design.

Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>

hw/pci-bridge/Makefile.objs

@@ -1,4 +1,5 @@
 common-obj-y += pci_bridge_dev.o
+common-obj-y += pci_expander_bridge.o
 common-obj-$(CONFIG_XIO3130) += xio3130_upstream.o xio3130_downstream.o
 common-obj-$(CONFIG_IOH3420) += ioh3420.o
 common-obj-$(CONFIG_I82801B11) += i82801b11.o

hw/pci-bridge/pci_expander_bridge.c

@@ -0,0 +1,196 @@
+/*
+ * PCI Expander Bridge Device Emulation
+ *
+ * Copyright (C) 2015 Red Hat Inc
+ *
+ * Authors:
+ *   Marcel Apfelbaum <marcel@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "hw/pci/pci.h"
+#include "hw/pci/pci_bus.h"
+#include "hw/pci/pci_host.h"
+#include "hw/pci/pci_bus.h"
+#include "hw/i386/pc.h"
+#include "qemu/range.h"
+#include "qemu/error-report.h"
+
+#define TYPE_PXB_BUS "pxb-bus"
+#define PXB_BUS(obj) OBJECT_CHECK(PXBBus, (obj), TYPE_PXB_BUS)
+
+typedef struct PXBBus {
+    /*< private >*/
+    PCIBus parent_obj;
+    /*< public >*/
+
+    char bus_path[8];
+} PXBBus;
+
+#define TYPE_PXB_DEVICE "pxb"
+#define PXB_DEV(obj) OBJECT_CHECK(PXBDev, (obj), TYPE_PXB_DEVICE)
+
+typedef struct PXBDev {
+    /*< private >*/
+    PCIDevice parent_obj;
+    /*< public >*/
+
+    uint8_t bus_nr;
+} PXBDev;
+
+#define TYPE_PXB_HOST "pxb-host"
+
+static int pxb_bus_num(PCIBus *bus)
+{
+    PXBDev *pxb = PXB_DEV(bus->parent_dev);
+
+    return pxb->bus_nr;
+}
+
+static bool pxb_is_root(PCIBus *bus)
+{
+    return true; /* by definition */
+}
+
+static void pxb_bus_class_init(ObjectClass *class, void *data)
+{
+    PCIBusClass *pbc = PCI_BUS_CLASS(class);
+
+    pbc->bus_num = pxb_bus_num;
+    pbc->is_root = pxb_is_root;
+}
+
+static const TypeInfo pxb_bus_info = {
+    .name          = TYPE_PXB_BUS,
+    .parent        = TYPE_PCI_BUS,
+    .instance_size = sizeof(PXBBus),
+    .class_init    = pxb_bus_class_init,
+};
+
+static const char *pxb_host_root_bus_path(PCIHostState *host_bridge,
+                                          PCIBus *rootbus)
+{
+    PXBBus *bus = PXB_BUS(rootbus);
+
+    snprintf(bus->bus_path, 8, "0000:%02x", pxb_bus_num(rootbus));
+    return bus->bus_path;
+}
+
+static void pxb_host_class_init(ObjectClass *class, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(class);
+    PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_CLASS(class);
+
+    dc->fw_name = "pci";
+    hc->root_bus_path = pxb_host_root_bus_path;
+}
+
+static const TypeInfo pxb_host_info = {
+    .name          = TYPE_PXB_HOST,
+    .parent        = TYPE_PCI_HOST_BRIDGE,
+    .class_init    = pxb_host_class_init,
+};
+
+/*
+ * Registers the PXB bus as a child of the i440fx root bus.
+ *
+ * Returns 0 on successs, -1 if i440fx host was not
+ * found or the bus number is already in use.
+ */
+static int pxb_register_bus(PCIDevice *dev, PCIBus *pxb_bus)
+{
+    PCIBus *bus = dev->bus;
+    int pxb_bus_num = pci_bus_num(pxb_bus);
+
+    if (bus->parent_dev) {
+        error_report("PXB devices can be attached only to root bus.");
+        return -1;
+    }
+
+    QLIST_FOREACH(bus, &bus->child, sibling) {
+        if (pci_bus_num(bus) == pxb_bus_num) {
+            error_report("Bus %d is already in use.", pxb_bus_num);
+            return -1;
+        }
+    }
+    QLIST_INSERT_HEAD(&dev->bus->child, pxb_bus, sibling);
+
+    return 0;
+}
+
+static int pxb_dev_initfn(PCIDevice *dev)
+{
+    PXBDev *pxb = PXB_DEV(dev);
+    DeviceState *ds, *bds;
+    PCIBus *bus;
+    const char *dev_name = NULL;
+
+    if (dev->qdev.id && *dev->qdev.id) {
+        dev_name = dev->qdev.id;
+    }
+
+    ds = qdev_create(NULL, TYPE_PXB_HOST);
+    bus = pci_bus_new(ds, "pxb-internal", 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 = pci_swizzle_map_irq_fn;
+
+    bds = qdev_create(BUS(bus), "pci-bridge");
+    bds->id = dev_name;
+    qdev_prop_set_uint8(bds, "chassis_nr", pxb->bus_nr);
+
+    PCI_HOST_BRIDGE(ds)->bus = bus;
+
+    if (pxb_register_bus(dev, bus)) {
+        return -EINVAL;
+    }
+
+    qdev_init_nofail(ds);
+    qdev_init_nofail(bds);
+
+    pci_word_test_and_set_mask(dev->config + PCI_STATUS,
+                               PCI_STATUS_66MHZ | PCI_STATUS_FAST_BACK);
+    pci_config_set_class(dev->config, PCI_CLASS_BRIDGE_HOST);
+
+    return 0;
+}
+
+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_END_OF_LIST(),
+};
+
+static void pxb_dev_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
+
+    k->init = pxb_dev_initfn;
+    k->vendor_id = PCI_VENDOR_ID_REDHAT;
+    k->device_id = PCI_DEVICE_ID_REDHAT_PXB;
+    k->class_id = PCI_CLASS_BRIDGE_HOST;
+
+    dc->desc = "PCI Expander Bridge";
+    dc->props = pxb_dev_properties;
+}
+
+static const TypeInfo pxb_dev_info = {
+    .name          = TYPE_PXB_DEVICE,
+    .parent        = TYPE_PCI_DEVICE,
+    .instance_size = sizeof(PXBDev),
+    .class_init    = pxb_dev_class_init,
+};
+
+static void pxb_register_types(void)
+{
+    type_register_static(&pxb_bus_info);
+    type_register_static(&pxb_host_info);
+    type_register_static(&pxb_dev_info);
+}
+
+type_init(pxb_register_types)

include/hw/pci/pci.h

@@ -91,6 +91,7 @@
 #define PCI_DEVICE_ID_REDHAT_ROCKER      0x0006
 #define PCI_DEVICE_ID_REDHAT_SDHCI       0x0007
 #define PCI_DEVICE_ID_REDHAT_PCIE_HOST   0x0008
+#define PCI_DEVICE_ID_REDHAT_PXB         0x0009
 #define PCI_DEVICE_ID_REDHAT_QXL         0x0100
 
 #define FMT_PCIBUS                      PRIx64