Re: [Xen-devel] [PATCH v2 2/4] Extend device listener interface for PCI to PCI bridges

[Don Slutz <dslutz@xxxxxxxxxxx>]

On 06/09/15 05:08, Paul Durrant wrote:
>> -----Original Message-----
>> From: Don Slutz [mailto:dslutz@xxxxxxxxxxx]
>> Sent: 08 June 2015 22:19
>> To: qemu-devel@xxxxxxxxxx; xen-devel@xxxxxxxxxxxxx
>> Cc: Michael S. Tsirkin; Paul Durrant; Stefano Stabellini; Don Slutz; Don 
>> Slutz
>> Subject: [PATCH v2 2/4] Extend device listener interface for PCI to PCI
>> bridges
>>
>> The commit 707ff80021ccd7a68f4b3d2c44eebf87efbb41c4 assumed that a
>> PCI device has a static address.  This is not true for PCI devices
>> that are on the secondary bus of a PCI to PCI bridge.
>>
>> BIOS and/or guest OS can change the secondary bus number to a new
>> value at any time.
>>
>> Extend the device listener interface to be called when ever the
>> secondary bus number is set to a new value.  This new interface
>> is called for all PCI devices that are on the secondary bridge.
>>
> 
> Can't you just make unrealize and realize calls back-to-back when the bus 
> number changes, rather than having a new callback?
> 

That is what V1 had.  Michael S. Tsirkin did not like this.

   -Don Slutz

>   Paul
> 
>> Signed-off-by: Don Slutz <dslutz@xxxxxxxxxxx>
>> CC: Don Slutz <don.slutz@xxxxxxxxx>
>> ---
>>  hw/core/qdev.c         |  7 +++++++
>>  hw/pci/pci_bridge.c    | 18 ++++++++++++++++++
>>  include/hw/qdev-core.h |  3 +++
>>  3 files changed, 28 insertions(+)
>>
>> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
>> index b0f0f84..7728ee7 100644
>> --- a/hw/core/qdev.c
>> +++ b/hw/core/qdev.c
>> @@ -239,6 +239,13 @@ void device_listener_unregister(DeviceListener
>> *listener)
>>      QTAILQ_REMOVE(&device_listeners, listener, link);
>>  }
>>
>> +void device_listener_change_pci_bus_num(PCIBus *b, PCIDevice *d, void
>> *opaque)
>> +{
>> +    uint8_t oldbus = GPOINTER_TO_INT(opaque);
>> +
>> +    DEVICE_LISTENER_CALL(change_pci_bus_num, Forward, d, oldbus);
>> +}
>> +
>>  static void device_realize(DeviceState *dev, Error **errp)
>>  {
>>      DeviceClass *dc = DEVICE_GET_CLASS(dev);
>> diff --git a/hw/pci/pci_bridge.c b/hw/pci/pci_bridge.c
>> index 40c97b1..742c4d8 100644
>> --- a/hw/pci/pci_bridge.c
>> +++ b/hw/pci/pci_bridge.c
>> @@ -248,6 +248,7 @@ void pci_bridge_write_config(PCIDevice *d,
>>      PCIBridge *s = PCI_BRIDGE(d);
>>      uint16_t oldctl = pci_get_word(d->config + PCI_BRIDGE_CONTROL);
>>      uint16_t newctl;
>> +    uint8_t oldbus = pci_get_byte(d->config + PCI_SECONDARY_BUS);
>>
>>      pci_default_write_config(d, address, val, len);
>>
>> @@ -265,6 +266,14 @@ void pci_bridge_write_config(PCIDevice *d,
>>          pci_bridge_update_mappings(s);
>>      }
>>
>> +    if (oldbus != pci_get_byte(d->config + PCI_SECONDARY_BUS)) {
>> +        PCIBus *sec_bus = pci_bridge_get_sec_bus(s);
>> +
>> +        pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
>> +                            device_listener_change_pci_bus_num,
>> +                            GINT_TO_POINTER(oldbus));
>> +    }
>> +
>>      newctl = pci_get_word(d->config + PCI_BRIDGE_CONTROL);
>>      if (~oldctl & newctl & PCI_BRIDGE_CTL_BUS_RESET) {
>>          /* Trigger hot reset on 0->1 transition. */
>> @@ -297,6 +306,7 @@ void pci_bridge_reset(DeviceState *qdev)
>>  {
>>      PCIDevice *dev = PCI_DEVICE(qdev);
>>      uint8_t *conf = dev->config;
>> +    uint8_t oldbus = conf[PCI_SECONDARY_BUS];
>>
>>      conf[PCI_PRIMARY_BUS] = 0;
>>      conf[PCI_SECONDARY_BUS] = 0;
>> @@ -329,6 +339,14 @@ void pci_bridge_reset(DeviceState *qdev)
>>      pci_set_long(conf + PCI_PREF_LIMIT_UPPER32, 0);
>>
>>      pci_set_word(conf + PCI_BRIDGE_CONTROL, 0);
>> +
>> +    if (oldbus) {
>> +        PCIBus *sec_bus = pci_bridge_get_sec_bus(PCI_BRIDGE(dev));
>> +
>> +        pci_for_each_device(sec_bus, pci_bus_num(sec_bus),
>> +                            device_listener_change_pci_bus_num,
>> +                            GINT_TO_POINTER(oldbus));
>> +    }
>>  }
>>
>>  /* default qdev initialization function for PCI-to-PCI bridge */
>> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
>> index d4be92f..154b4c1 100644
>> --- a/include/hw/qdev-core.h
>> +++ b/include/hw/qdev-core.h
>> @@ -168,6 +168,8 @@ struct DeviceState {
>>  struct DeviceListener {
>>      void (*realize)(DeviceListener *listener, DeviceState *dev);
>>      void (*unrealize)(DeviceListener *listener, DeviceState *dev);
>> +    void (*change_pci_bus_num)(DeviceListener *listener, PCIDevice *d,
>> +                               uint8_t oldbus);
>>      QTAILQ_ENTRY(DeviceListener) link;
>>  };
>>
>> @@ -387,5 +389,6 @@ static inline bool qbus_is_hotpluggable(BusState
>> *bus)
>>
>>  void device_listener_register(DeviceListener *listener);
>>  void device_listener_unregister(DeviceListener *listener);
>> +void device_listener_change_pci_bus_num(PCIBus *b, PCIDevice *d, void
>> *opaque);
>>
>>  #endif
>> --
>> 1.8.4
> 

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