[Qemu-devel] Re: [PATCH V5 17/29] pci: make pci configuration transaction more accurate.

["Michael S. Tsirkin" <mst@redhat.com>]

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