Patchwork [V5,17/29] pci: make pci configuration transaction more accurate.

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Submitter Isaku Yamahata
Date Oct. 9, 2009, 6:28 a.m.
Message ID <1255069742-15724-18-git-send-email-yamahata@valinux.co.jp>
Download mbox | patch
Permalink /patch/35565/
State Under Review
Headers show

Comments

Isaku Yamahata - Oct. 9, 2009, 6:28 a.m.
This patch sorts out/enhances pci code to track pci bus topology
more accurately.
- Track host bus bridge with pci domain number. Although the
  current qemu implementation supports only pci domian 0 yet.
- Track pci bridge parent-child relationship.
When looking down from pci host bus for pci sub bus, be aware of
secondary bus/subordinate bus.
Thus pci configuration transaction is more accurately emulated.

This patch adds new member to PCIBus to track pci bus topology.
Since qdev already tracks down bus relationship, those new member
wouldn't be necessary.
However it would be addressed later because not all the pci device
isn't converted to qdev yet.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
---
 hw/pci-hotplug.c |    4 +-
 hw/pci.c         |  115 ++++++++++++++++++++++++++++++++++++++++--------------
 hw/pci.h         |    8 ++-
 3 files changed, 92 insertions(+), 35 deletions(-)
Michael S. Tsirkin - Oct. 9, 2009, 12:52 p.m.
On Fri, Oct 09, 2009 at 03:28:50PM +0900, Isaku Yamahata wrote:
> This patch sorts out/enhances pci code to track pci bus topology
> more accurately.
> - Track host bus bridge with pci domain number. Although the
>   current qemu implementation supports only pci domian 0 yet.
> - Track pci bridge parent-child relationship.
> When looking down from pci host bus for pci sub bus, be aware of
> secondary bus/subordinate bus.
> Thus pci configuration transaction is more accurately emulated.

Overall I think this is a good idea.

> This patch adds new member to PCIBus to track pci bus topology.
> Since qdev already tracks down bus relationship, those new member
> wouldn't be necessary.

Another point: why store these separately at all?
Can't we just use the pci config registers directly?

> However it would be addressed later because not all the pci device
> isn't converted to qdev yet.
> 
> Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>

Some comments below. Could you please test something like windows
boot and verify that using a more complex structure does not
affect boot times?

> ---
>  hw/pci-hotplug.c |    4 +-
>  hw/pci.c         |  115 ++++++++++++++++++++++++++++++++++++++++--------------
>  hw/pci.h         |    8 ++-
>  3 files changed, 92 insertions(+), 35 deletions(-)
> 
> diff --git a/hw/pci-hotplug.c b/hw/pci-hotplug.c
> index ccd2cf3..d50919b 100644
> --- a/hw/pci-hotplug.c
> +++ b/hw/pci-hotplug.c
> @@ -87,7 +87,7 @@ void drive_hot_add(Monitor *mon, const QDict *qdict)
>          if (pci_read_devaddr(mon, pci_addr, &dom, &pci_bus, &slot)) {
>              goto err;
>          }
> -        dev = pci_find_device(pci_bus, slot, 0);
> +        dev = pci_find_device(pci_find_host_bus(0), pci_bus, slot, 0);
>          if (!dev) {
>              monitor_printf(mon, "no pci device with address %s\n", pci_addr);
>              goto err;
> @@ -222,7 +222,7 @@ void pci_device_hot_remove(Monitor *mon, const char *pci_addr)
>          return;
>      }
>  
> -    d = pci_find_device(bus, slot, 0);
> +    d = pci_find_device(pci_find_host_bus(0), bus, slot, 0);
>      if (!d) {
>          monitor_printf(mon, "slot %d empty\n", slot);
>          return;
> diff --git a/hw/pci.c b/hw/pci.c
> index ee3ab05..33cc476 100644
> --- a/hw/pci.c
> +++ b/hw/pci.c
> @@ -34,9 +34,12 @@
>  # define PCI_DPRINTF(format, ...)       do { } while (0)
>  #endif
>  
> +#define PCI_BUS_NUM_MAX 255
>  struct PCIBus {
>      BusState qbus;
>      int bus_num;
> +    int sub_bus;
> +
>      int devfn_min;
>      pci_set_irq_fn set_irq;
>      pci_map_irq_fn map_irq;
> @@ -45,7 +48,10 @@ struct PCIBus {
>      void *irq_opaque;
>      PCIDevice *devices[256];
>      PCIDevice *parent_dev;
> -    PCIBus *next;
> +
> +    QLIST_HEAD(, PCIBus) child; /* this will be replaced by qdev later */
> +    QLIST_ENTRY(PCIBus) sibling;/* this will be replaced by qdev later */
> +
>      /* The bus IRQ state is the logical OR of the connected devices.
>         Keep a count of the number of devices with raised IRQs.  */
>      int nirq;
> @@ -70,7 +76,13 @@ static void pci_set_irq(void *opaque, int irq_num, int level);
>  target_phys_addr_t pci_mem_base;
>  static uint16_t pci_default_sub_vendor_id = PCI_SUBVENDOR_ID_REDHAT_QUMRANET;
>  static uint16_t pci_default_sub_device_id = PCI_SUBDEVICE_ID_QEMU;
> -static PCIBus *first_bus;
> +
> +struct PCIHostBus {
> +    int domain;
> +    struct PCIBus *bus;
> +    QLIST_ENTRY(PCIHostBus) next;
> +};
> +static QLIST_HEAD(, PCIHostBus) host_buses;
>  
>  static const VMStateDescription vmstate_pcibus = {
>      .name = "PCIBUS",
> @@ -128,6 +140,28 @@ static void pci_bus_reset(void *opaque)
>      }
>  }
>  
> +static void pci_host_bus_register(int domain, PCIBus *bus)
> +{
> +    struct PCIHostBus *host;
> +    host = qemu_mallocz(sizeof(*host));
> +    host->domain = domain;
> +    host->bus = bus;
> +    QLIST_INSERT_HEAD(&host_buses, host, next);
> +}
> +
> +PCIBus *pci_find_host_bus(int domain)
> +{
> +    struct PCIHostBus *host;
> +
> +    QLIST_FOREACH(host, &host_buses, next) {
> +        if (host->domain == domain) {
> +            return host->bus;
> +        }
> +    }
> +
> +    return NULL;
> +}
> +
>  void pci_bus_new_inplace(PCIBus *bus, DeviceState *parent,
>                           const char *name, int devfn_min)
>  {
> @@ -135,8 +169,13 @@ void pci_bus_new_inplace(PCIBus *bus, DeviceState *parent,
>  
>      qbus_create_inplace(&bus->qbus, &pci_bus_info, parent, name);
>      bus->devfn_min = devfn_min;
> -    bus->next = first_bus;
> -    first_bus = bus;
> +
> +    /* host bridge */
> +    bus->bus_num = 0;
> +    bus->sub_bus = PCI_BUS_NUM_MAX;
> +    QLIST_INIT(&bus->child);
> +    pci_host_bus_register(0, bus); /* for now only pci domain 0 is supported */
> +
>      vmstate_register(nbus++, &vmstate_pcibus, bus);
>      qemu_register_reset(pci_bus_reset, bus);
>  }
> @@ -178,7 +217,8 @@ PCIBus *pci_register_bus(DeviceState *parent, const char *name,
>      return bus;
>  }
>  
> -static void pci_register_secondary_bus(PCIBus *bus,
> +static void pci_register_secondary_bus(PCIBus *parent,
> +                                       PCIBus *bus,
>                                         PCIDevice *dev,
>                                         pci_map_irq_fn map_irq,
>                                         const char *name)
> @@ -186,8 +226,11 @@ static void pci_register_secondary_bus(PCIBus *bus,

BTW, should not it be possible to remove buses?
I don't see code removing bus from the tree, anywhere.

>      qbus_create_inplace(&bus->qbus, &pci_bus_info, &dev->qdev, name);
>      bus->map_irq = map_irq;
>      bus->parent_dev = dev;
> -    bus->next = dev->bus->next;
> -    dev->bus->next = bus;
> +
> +    bus->bus_num = dev->config[PCI_SECONDARY_BUS];
> +    bus->sub_bus = dev->config[PCI_SUBORDINATE_BUS];

These seem unnecessary: init value is 0 anyway.
But you need to update these at reset, I don't see where you do this.

> +    QLIST_INIT(&bus->child);
> +    QLIST_INSERT_HEAD(&parent->child, bus, sibling);
>  }
>  
>  int pci_bus_num(PCIBus *s)
> @@ -300,7 +343,7 @@ static int pci_parse_devaddr(const char *addr, int *domp, int *busp, unsigned *s
>  	return -1;
>  
>      /* Note: QEMU doesn't implement domains other than 0 */
> -    if (dom != 0 || pci_find_bus(bus) == NULL)
> +    if (pci_find_bus(pci_find_host_bus(dom), bus) == NULL)

Replace == NULL with ! please.

>  	return -1;
>  
>      *domp = dom;
> @@ -330,7 +373,7 @@ PCIBus *pci_get_bus_devfn(int *devfnp, const char *devaddr)
>  
>      if (!devaddr) {
>          *devfnp = -1;
> -        return pci_find_bus(0);
> +        return pci_find_bus(pci_find_host_bus(0), 0);
>      }
>  
>      if (pci_parse_devaddr(devaddr, &dom, &bus, &slot) < 0) {
> @@ -338,7 +381,7 @@ PCIBus *pci_get_bus_devfn(int *devfnp, const char *devaddr)
>      }
>  
>      *devfnp = slot << 3;
> -    return pci_find_bus(bus);
> +    return pci_find_bus(pci_find_host_bus(0), bus);
>  }
>  
>  static void pci_init_cmask(PCIDevice *dev)
> @@ -622,8 +665,7 @@ void pci_data_write(void *opaque, uint32_t addr, uint32_t val, int len)
>                  addr, val, len);
>  #endif
>      bus_num = (addr >> 16) & 0xff;
> -    while (s && s->bus_num != bus_num)
> -        s = s->next;
> +    s = pci_find_bus(s, bus_num);
>      if (!s)
>          return;
>      pci_dev = s->devices[(addr >> 8) & 0xff];
> @@ -643,8 +685,7 @@ uint32_t pci_data_read(void *opaque, uint32_t addr, int len)
>      uint32_t val;
>  
>      bus_num = (addr >> 16) & 0xff;
> -    while (s && s->bus_num != bus_num)
> -        s= s->next;
> +    s = pci_find_bus(s, bus_num);
>      if (!s)
>          goto fail;
>      pci_dev = s->devices[(addr >> 8) & 0xff];
> @@ -750,7 +791,7 @@ static const pci_class_desc pci_class_descriptions[] =
>      { 0, NULL}
>  };
>  
> -static void pci_info_device(PCIDevice *d)
> +static void pci_info_device(PCIBus *bus, PCIDevice *d)
>  {
>      Monitor *mon = cur_mon;
>      int i, class;
> @@ -805,30 +846,32 @@ static void pci_info_device(PCIDevice *d)
>      }
>      monitor_printf(mon, "      id \"%s\"\n", d->qdev.id ? d->qdev.id : "");
>      if (class == 0x0604 && d->config[0x19] != 0) {
> -        pci_for_each_device(d->config[0x19], pci_info_device);
> +        pci_for_each_device(bus, d->config[0x19], pci_info_device);
>      }
>  }
>  
> -void pci_for_each_device(int bus_num, void (*fn)(PCIDevice *d))
> +void pci_for_each_device(PCIBus *bus, int bus_num,
> +                         void (*fn)(PCIBus *b, PCIDevice *d))
>  {
> -    PCIBus *bus = first_bus;
>      PCIDevice *d;
>      int devfn;
>  
> -    while (bus && bus->bus_num != bus_num)
> -        bus = bus->next;
> +    bus = pci_find_bus(bus, bus_num);
>      if (bus) {
>          for(devfn = 0; devfn < 256; devfn++) {
>              d = bus->devices[devfn];
>              if (d)
> -                fn(d);
> +                fn(bus, d);
>          }
>      }
>  }
>  
>  void pci_info(Monitor *mon)
>  {
> -    pci_for_each_device(0, pci_info_device);
> +    struct PCIHostBus *host;
> +    QLIST_FOREACH(host, &host_buses, next) {
> +        pci_for_each_device(host->bus, 0, pci_info_device);
> +    }
>  }
>  
>  static const char * const pci_nic_models[] = {
> @@ -917,21 +960,33 @@ static void pci_bridge_write_config(PCIDevice *d,
>  
>      pci_default_write_config(d, address, val, len);
>      s->bus.bus_num = d->config[PCI_SECONDARY_BUS];
> +    s->bus.sub_bus = d->config[PCI_SUBORDINATE_BUS];
>  }
>  
> -PCIBus *pci_find_bus(int bus_num)
> +PCIBus *pci_find_bus(PCIBus *bus, int bus_num)
>  {
> -    PCIBus *bus = first_bus;
> +    PCIBus *sec;
>  
> -    while (bus && bus->bus_num != bus_num)
> -        bus = bus->next;
> +    if (!bus)
> +        return NULL;
>  
> -    return bus;
> +    if (bus->bus_num == bus_num) {
> +        return bus;
> +    }
> +
> +    /* try child bus */
> +    QLIST_FOREACH(sec, &bus->child, sibling) {
> +        if (sec->bus_num <= bus_num && bus_num <= sec->sub_bus) {
> +            return pci_find_bus(sec, bus_num);
> +        }
> +    }
> +
> +    return NULL;
>  }
>  
> -PCIDevice *pci_find_device(int bus_num, int slot, int function)
> +PCIDevice *pci_find_device(PCIBus *bus, int bus_num, int slot, int function)
>  {
> -    PCIBus *bus = pci_find_bus(bus_num);
> +    bus = pci_find_bus(bus, bus_num);
>  
>      if (!bus)
>          return NULL;
> @@ -973,7 +1028,7 @@ PCIBus *pci_bridge_init(PCIBus *bus, int devfn, uint16_t vid, uint16_t did,
>      qdev_init_nofail(&dev->qdev);
>  
>      s = DO_UPCAST(PCIBridge, dev, dev);
> -    pci_register_secondary_bus(&s->bus, &s->dev, map_irq, name);
> +    pci_register_secondary_bus(bus, &s->bus, &s->dev, map_irq, name);
>      return &s->bus;
>  }
>  
> diff --git a/hw/pci.h b/hw/pci.h
> index 269981a..3a3838d 100644
> --- a/hw/pci.h
> +++ b/hw/pci.h
> @@ -159,6 +159,7 @@ typedef struct PCIIORegion {
>  #define PCI_COMMAND_RESERVED_MASK_HI (PCI_COMMAND_RESERVED >> 8)
>  
>  /* Header type 1 (PCI-to-PCI bridges) */
> +#define PCI_SUBORDINATE_BUS     0x1a    /* Highest bus number behind the bridge */
>  #define PCI_ROM_ADDRESS1        0x38    /* Same as PCI_ROM_ADDRESS, but for htype 1 */
>  
>  /* Size of the standard PCI config header */
> @@ -270,9 +271,10 @@ PCIDevice *pci_nic_init_nofail(NICInfo *nd, const char *default_model,
>  void pci_data_write(void *opaque, uint32_t addr, uint32_t val, int len);
>  uint32_t pci_data_read(void *opaque, uint32_t addr, int len);
>  int pci_bus_num(PCIBus *s);
> -void pci_for_each_device(int bus_num, void (*fn)(PCIDevice *d));
> -PCIBus *pci_find_bus(int bus_num);
> -PCIDevice *pci_find_device(int bus_num, int slot, int function);
> +void pci_for_each_device(PCIBus *bus, int bus_num, void (*fn)(PCIBus *bus, PCIDevice *d));
> +PCIBus *pci_find_host_bus(int domain);
> +PCIBus *pci_find_bus(PCIBus *bus, int bus_num);
> +PCIDevice *pci_find_device(PCIBus *bus, int bus_num, int slot, int function);
>  PCIBus *pci_get_bus_devfn(int *devfnp, const char *devaddr);
>  
>  int pci_read_devaddr(Monitor *mon, const char *addr, int *domp, int *busp,
> -- 
> 1.6.0.2

Patch

diff --git a/hw/pci-hotplug.c b/hw/pci-hotplug.c
index ccd2cf3..d50919b 100644
--- a/hw/pci-hotplug.c
+++ b/hw/pci-hotplug.c
@@ -87,7 +87,7 @@  void drive_hot_add(Monitor *mon, const QDict *qdict)
         if (pci_read_devaddr(mon, pci_addr, &dom, &pci_bus, &slot)) {
             goto err;
         }
-        dev = pci_find_device(pci_bus, slot, 0);
+        dev = pci_find_device(pci_find_host_bus(0), pci_bus, slot, 0);
         if (!dev) {
             monitor_printf(mon, "no pci device with address %s\n", pci_addr);
             goto err;
@@ -222,7 +222,7 @@  void pci_device_hot_remove(Monitor *mon, const char *pci_addr)
         return;
     }
 
-    d = pci_find_device(bus, slot, 0);
+    d = pci_find_device(pci_find_host_bus(0), bus, slot, 0);
     if (!d) {
         monitor_printf(mon, "slot %d empty\n", slot);
         return;
diff --git a/hw/pci.c b/hw/pci.c
index ee3ab05..33cc476 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -34,9 +34,12 @@ 
 # define PCI_DPRINTF(format, ...)       do { } while (0)
 #endif
 
+#define PCI_BUS_NUM_MAX 255
 struct PCIBus {
     BusState qbus;
     int bus_num;
+    int sub_bus;
+
     int devfn_min;
     pci_set_irq_fn set_irq;
     pci_map_irq_fn map_irq;
@@ -45,7 +48,10 @@  struct PCIBus {
     void *irq_opaque;
     PCIDevice *devices[256];
     PCIDevice *parent_dev;
-    PCIBus *next;
+
+    QLIST_HEAD(, PCIBus) child; /* this will be replaced by qdev later */
+    QLIST_ENTRY(PCIBus) sibling;/* this will be replaced by qdev later */
+
     /* The bus IRQ state is the logical OR of the connected devices.
        Keep a count of the number of devices with raised IRQs.  */
     int nirq;
@@ -70,7 +76,13 @@  static void pci_set_irq(void *opaque, int irq_num, int level);
 target_phys_addr_t pci_mem_base;
 static uint16_t pci_default_sub_vendor_id = PCI_SUBVENDOR_ID_REDHAT_QUMRANET;
 static uint16_t pci_default_sub_device_id = PCI_SUBDEVICE_ID_QEMU;
-static PCIBus *first_bus;
+
+struct PCIHostBus {
+    int domain;
+    struct PCIBus *bus;
+    QLIST_ENTRY(PCIHostBus) next;
+};
+static QLIST_HEAD(, PCIHostBus) host_buses;
 
 static const VMStateDescription vmstate_pcibus = {
     .name = "PCIBUS",
@@ -128,6 +140,28 @@  static void pci_bus_reset(void *opaque)
     }
 }
 
+static void pci_host_bus_register(int domain, PCIBus *bus)
+{
+    struct PCIHostBus *host;
+    host = qemu_mallocz(sizeof(*host));
+    host->domain = domain;
+    host->bus = bus;
+    QLIST_INSERT_HEAD(&host_buses, host, next);
+}
+
+PCIBus *pci_find_host_bus(int domain)
+{
+    struct PCIHostBus *host;
+
+    QLIST_FOREACH(host, &host_buses, next) {
+        if (host->domain == domain) {
+            return host->bus;
+        }
+    }
+
+    return NULL;
+}
+
 void pci_bus_new_inplace(PCIBus *bus, DeviceState *parent,
                          const char *name, int devfn_min)
 {
@@ -135,8 +169,13 @@  void pci_bus_new_inplace(PCIBus *bus, DeviceState *parent,
 
     qbus_create_inplace(&bus->qbus, &pci_bus_info, parent, name);
     bus->devfn_min = devfn_min;
-    bus->next = first_bus;
-    first_bus = bus;
+
+    /* host bridge */
+    bus->bus_num = 0;
+    bus->sub_bus = PCI_BUS_NUM_MAX;
+    QLIST_INIT(&bus->child);
+    pci_host_bus_register(0, bus); /* for now only pci domain 0 is supported */
+
     vmstate_register(nbus++, &vmstate_pcibus, bus);
     qemu_register_reset(pci_bus_reset, bus);
 }
@@ -178,7 +217,8 @@  PCIBus *pci_register_bus(DeviceState *parent, const char *name,
     return bus;
 }
 
-static void pci_register_secondary_bus(PCIBus *bus,
+static void pci_register_secondary_bus(PCIBus *parent,
+                                       PCIBus *bus,
                                        PCIDevice *dev,
                                        pci_map_irq_fn map_irq,
                                        const char *name)
@@ -186,8 +226,11 @@  static void pci_register_secondary_bus(PCIBus *bus,
     qbus_create_inplace(&bus->qbus, &pci_bus_info, &dev->qdev, name);
     bus->map_irq = map_irq;
     bus->parent_dev = dev;
-    bus->next = dev->bus->next;
-    dev->bus->next = bus;
+
+    bus->bus_num = dev->config[PCI_SECONDARY_BUS];
+    bus->sub_bus = dev->config[PCI_SUBORDINATE_BUS];
+    QLIST_INIT(&bus->child);
+    QLIST_INSERT_HEAD(&parent->child, bus, sibling);
 }
 
 int pci_bus_num(PCIBus *s)
@@ -300,7 +343,7 @@  static int pci_parse_devaddr(const char *addr, int *domp, int *busp, unsigned *s
 	return -1;
 
     /* Note: QEMU doesn't implement domains other than 0 */
-    if (dom != 0 || pci_find_bus(bus) == NULL)
+    if (pci_find_bus(pci_find_host_bus(dom), bus) == NULL)
 	return -1;
 
     *domp = dom;
@@ -330,7 +373,7 @@  PCIBus *pci_get_bus_devfn(int *devfnp, const char *devaddr)
 
     if (!devaddr) {
         *devfnp = -1;
-        return pci_find_bus(0);
+        return pci_find_bus(pci_find_host_bus(0), 0);
     }
 
     if (pci_parse_devaddr(devaddr, &dom, &bus, &slot) < 0) {
@@ -338,7 +381,7 @@  PCIBus *pci_get_bus_devfn(int *devfnp, const char *devaddr)
     }
 
     *devfnp = slot << 3;
-    return pci_find_bus(bus);
+    return pci_find_bus(pci_find_host_bus(0), bus);
 }
 
 static void pci_init_cmask(PCIDevice *dev)
@@ -622,8 +665,7 @@  void pci_data_write(void *opaque, uint32_t addr, uint32_t val, int len)
                 addr, val, len);
 #endif
     bus_num = (addr >> 16) & 0xff;
-    while (s && s->bus_num != bus_num)
-        s = s->next;
+    s = pci_find_bus(s, bus_num);
     if (!s)
         return;
     pci_dev = s->devices[(addr >> 8) & 0xff];
@@ -643,8 +685,7 @@  uint32_t pci_data_read(void *opaque, uint32_t addr, int len)
     uint32_t val;
 
     bus_num = (addr >> 16) & 0xff;
-    while (s && s->bus_num != bus_num)
-        s= s->next;
+    s = pci_find_bus(s, bus_num);
     if (!s)
         goto fail;
     pci_dev = s->devices[(addr >> 8) & 0xff];
@@ -750,7 +791,7 @@  static const pci_class_desc pci_class_descriptions[] =
     { 0, NULL}
 };
 
-static void pci_info_device(PCIDevice *d)
+static void pci_info_device(PCIBus *bus, PCIDevice *d)
 {
     Monitor *mon = cur_mon;
     int i, class;
@@ -805,30 +846,32 @@  static void pci_info_device(PCIDevice *d)
     }
     monitor_printf(mon, "      id \"%s\"\n", d->qdev.id ? d->qdev.id : "");
     if (class == 0x0604 && d->config[0x19] != 0) {
-        pci_for_each_device(d->config[0x19], pci_info_device);
+        pci_for_each_device(bus, d->config[0x19], pci_info_device);
     }
 }
 
-void pci_for_each_device(int bus_num, void (*fn)(PCIDevice *d))
+void pci_for_each_device(PCIBus *bus, int bus_num,
+                         void (*fn)(PCIBus *b, PCIDevice *d))
 {
-    PCIBus *bus = first_bus;
     PCIDevice *d;
     int devfn;
 
-    while (bus && bus->bus_num != bus_num)
-        bus = bus->next;
+    bus = pci_find_bus(bus, bus_num);
     if (bus) {
         for(devfn = 0; devfn < 256; devfn++) {
             d = bus->devices[devfn];
             if (d)
-                fn(d);
+                fn(bus, d);
         }
     }
 }
 
 void pci_info(Monitor *mon)
 {
-    pci_for_each_device(0, pci_info_device);
+    struct PCIHostBus *host;
+    QLIST_FOREACH(host, &host_buses, next) {
+        pci_for_each_device(host->bus, 0, pci_info_device);
+    }
 }
 
 static const char * const pci_nic_models[] = {
@@ -917,21 +960,33 @@  static void pci_bridge_write_config(PCIDevice *d,
 
     pci_default_write_config(d, address, val, len);
     s->bus.bus_num = d->config[PCI_SECONDARY_BUS];
+    s->bus.sub_bus = d->config[PCI_SUBORDINATE_BUS];
 }
 
-PCIBus *pci_find_bus(int bus_num)
+PCIBus *pci_find_bus(PCIBus *bus, int bus_num)
 {
-    PCIBus *bus = first_bus;
+    PCIBus *sec;
 
-    while (bus && bus->bus_num != bus_num)
-        bus = bus->next;
+    if (!bus)
+        return NULL;
 
-    return bus;
+    if (bus->bus_num == bus_num) {
+        return bus;
+    }
+
+    /* try child bus */
+    QLIST_FOREACH(sec, &bus->child, sibling) {
+        if (sec->bus_num <= bus_num && bus_num <= sec->sub_bus) {
+            return pci_find_bus(sec, bus_num);
+        }
+    }
+
+    return NULL;
 }
 
-PCIDevice *pci_find_device(int bus_num, int slot, int function)
+PCIDevice *pci_find_device(PCIBus *bus, int bus_num, int slot, int function)
 {
-    PCIBus *bus = pci_find_bus(bus_num);
+    bus = pci_find_bus(bus, bus_num);
 
     if (!bus)
         return NULL;
@@ -973,7 +1028,7 @@  PCIBus *pci_bridge_init(PCIBus *bus, int devfn, uint16_t vid, uint16_t did,
     qdev_init_nofail(&dev->qdev);
 
     s = DO_UPCAST(PCIBridge, dev, dev);
-    pci_register_secondary_bus(&s->bus, &s->dev, map_irq, name);
+    pci_register_secondary_bus(bus, &s->bus, &s->dev, map_irq, name);
     return &s->bus;
 }
 
diff --git a/hw/pci.h b/hw/pci.h
index 269981a..3a3838d 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -159,6 +159,7 @@  typedef struct PCIIORegion {
 #define PCI_COMMAND_RESERVED_MASK_HI (PCI_COMMAND_RESERVED >> 8)
 
 /* Header type 1 (PCI-to-PCI bridges) */
+#define PCI_SUBORDINATE_BUS     0x1a    /* Highest bus number behind the bridge */
 #define PCI_ROM_ADDRESS1        0x38    /* Same as PCI_ROM_ADDRESS, but for htype 1 */
 
 /* Size of the standard PCI config header */
@@ -270,9 +271,10 @@  PCIDevice *pci_nic_init_nofail(NICInfo *nd, const char *default_model,
 void pci_data_write(void *opaque, uint32_t addr, uint32_t val, int len);
 uint32_t pci_data_read(void *opaque, uint32_t addr, int len);
 int pci_bus_num(PCIBus *s);
-void pci_for_each_device(int bus_num, void (*fn)(PCIDevice *d));
-PCIBus *pci_find_bus(int bus_num);
-PCIDevice *pci_find_device(int bus_num, int slot, int function);
+void pci_for_each_device(PCIBus *bus, int bus_num, void (*fn)(PCIBus *bus, PCIDevice *d));
+PCIBus *pci_find_host_bus(int domain);
+PCIBus *pci_find_bus(PCIBus *bus, int bus_num);
+PCIDevice *pci_find_device(PCIBus *bus, int bus_num, int slot, int function);
 PCIBus *pci_get_bus_devfn(int *devfnp, const char *devaddr);
 
 int pci_read_devaddr(Monitor *mon, const char *addr, int *domp, int *busp,