Re: [Qemu-devel] [PATCH v6 3/7] hw/pci-bridge: introduce "hotplug" property

[Laszlo Ersek]

On 06/17/15 16:02, Michael S. Tsirkin wrote:
> On Wed, Jun 17, 2015 at 03:55:32PM +0200, Laszlo Ersek wrote:
>> On 06/17/15 15:42, Michael S. Tsirkin wrote:
>>> On Wed, Jun 17, 2015 at 02:45:01PM +0200, Laszlo Ersek wrote:
>>>> In the PCI expander bridge, we will want to disable those features of
>>>> pci-bridge that relate to SHPC (standard hotplug controller):
>>>>
>>>> - SHPC bar and underlying MemoryRegion
>>>> - interrupt (INTx or MSI)
>>>> - effective hotplug callbacks
>>>> - other SHPC hooks (initialization, cleanup, migration etc)
>>>>
>>>> Introduce a new feature bit in the PCIBridgeDev.flags field, and turn off
>>>> the above if the bit is explicitly cleared.
>>>>
>>>> Suggested-by: Michael S. Tsirkin <address@hidden>
>>>> Cc: Michael S. Tsirkin <address@hidden>
>>>> Cc: Marcel Apfelbaum <address@hidden>
>>>> Signed-off-by: Laszlo Ersek <address@hidden>
>>>
>>>
>>> I think I would prefer naming the property "shpc".
>>> In particular ACPI hotplug still works fine.
>>
>> Will do.
>>
>> Are you okay with the flag's name, PCI_BRIDGE_DEV_F_HOTPLUG? If not,
>> what would be your preference?
> 
> PCI_BRIDGE_DEV_F_SHPC_REQ
> 
> Also add macro for "shpc" property string to avoid duplication.
> Also clear msi explicitly - no need for that to depend on shpc.
> 
>> Should I also rename the helper function hotplug_enabled() to
>> shpc_enabled()?
> 
> It should be tested only once - before shpc is initialized.
> All other users should test QEMU_PCI_CAP_SHPC - if you like,
> using a helper shpc_present.

I'll make one attempt (in v7) to get this right. If I miss it, I'll ask
Marcel to please take over the series.

Thanks
Laszlo

> 
>>
>> Thanks
>> Laszlo
>>
>>>
>>>
>>>> ---
>>>>
>>>> Notes:
>>>>     v6:
>>>>     - new in v6 (replaces "hw/pci-bridge: create interrupt-less,
>>>>       hotplug-less bridge for PXB" from v5) [Michael]
>>>>     - I tested migration-to-file and migration-from-file, with a single PXB
>>>>       behind which a virtio-scsi HBA lived
>>>>     - No idea how to test the hotplug callbacks. I tried the device_add and
>>>>       device_del HMP commands with a virtio-scsi HBA behind the PXB, and 
>>>> the
>>>>       monitor reports no error at all; the callbacks don't seem to be
>>>>       reached.
>>>>     - Retested with windows 2012; it works
>>>>
>>>>  hw/pci-bridge/pci_bridge_dev.c | 90 
>>>> ++++++++++++++++++++++++++++++++++++------
>>>>  1 file changed, 78 insertions(+), 12 deletions(-)
>>>>
>>>> diff --git a/hw/pci-bridge/pci_bridge_dev.c 
>>>> b/hw/pci-bridge/pci_bridge_dev.c
>>>> index d697c7b..a0a1ce9 100644
>>>> --- a/hw/pci-bridge/pci_bridge_dev.c
>>>> +++ b/hw/pci-bridge/pci_bridge_dev.c
>>>> @@ -40,10 +40,16 @@ struct PCIBridgeDev {
>>>>      MemoryRegion bar;
>>>>      uint8_t chassis_nr;
>>>>  #define PCI_BRIDGE_DEV_F_MSI_REQ 0
>>>> +#define PCI_BRIDGE_DEV_F_HOTPLUG 1
>>>>      uint32_t flags;
>>>>  };
>>>>  typedef struct PCIBridgeDev PCIBridgeDev;
>>>>  
>>>> +static inline bool hotplug_enabled(const PCIBridgeDev *bridge_dev)
>>>> +{
>>>> +    return !!(bridge_dev->flags & (1u << PCI_BRIDGE_DEV_F_HOTPLUG));
>>>> +}
>>>> +
>>>>  static int pci_bridge_dev_initfn(PCIDevice *dev)
>>>>  {
>>>>      PCIBridge *br = PCI_BRIDGE(dev);
>>>> @@ -54,16 +60,26 @@ static int pci_bridge_dev_initfn(PCIDevice *dev)
>>>>      if (err) {
>>>>          goto bridge_error;
>>>>      }
>>>> -    dev->config[PCI_INTERRUPT_PIN] = 0x1;
>>>> -    memory_region_init(&bridge_dev->bar, OBJECT(dev), "shpc-bar", 
>>>> shpc_bar_size(dev));
>>>> -    err = shpc_init(dev, &br->sec_bus, &bridge_dev->bar, 0);
>>>> -    if (err) {
>>>> -        goto shpc_error;
>>>> +
>>>> +    if (hotplug_enabled(bridge_dev)) {
>>>> +        dev->config[PCI_INTERRUPT_PIN] = 0x1;
>>>> +        memory_region_init(&bridge_dev->bar, OBJECT(dev), "shpc-bar",
>>>> +                           shpc_bar_size(dev));
>>>> +        err = shpc_init(dev, &br->sec_bus, &bridge_dev->bar, 0);
>>>> +        if (err) {
>>>> +            goto shpc_error;
>>>> +        }
>>>>      }
>>>> +
>>>>      err = slotid_cap_init(dev, 0, bridge_dev->chassis_nr, 0);
>>>>      if (err) {
>>>>          goto slotid_error;
>>>>      }
>>>> +
>>>> +    if (!hotplug_enabled(bridge_dev)) {
>>>> +        return 0;
>>>> +    }
>>>> +
>>>>      if ((bridge_dev->flags & (1 << PCI_BRIDGE_DEV_F_MSI_REQ)) &&
>>>>          msi_supported) {
>>>>          err = msi_init(dev, 0, 1, true, true);
>>>> @@ -79,7 +95,9 @@ static int pci_bridge_dev_initfn(PCIDevice *dev)
>>>>  msi_error:
>>>>      slotid_cap_cleanup(dev);
>>>>  slotid_error:
>>>> -    shpc_cleanup(dev, &bridge_dev->bar);
>>>> +    if (hotplug_enabled(bridge_dev)) {
>>>> +        shpc_cleanup(dev, &bridge_dev->bar);
>>>> +    }
>>>>  shpc_error:
>>>>      pci_bridge_exitfn(dev);
>>>>  bridge_error:
>>>> @@ -89,53 +107,101 @@ bridge_error:
>>>>  static void pci_bridge_dev_exitfn(PCIDevice *dev)
>>>>  {
>>>>      PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(dev);
>>>> +
>>>>      if (msi_present(dev)) {
>>>>          msi_uninit(dev);
>>>>      }
>>>>      slotid_cap_cleanup(dev);
>>>> -    shpc_cleanup(dev, &bridge_dev->bar);
>>>> +    if (hotplug_enabled(bridge_dev)) {
>>>> +        shpc_cleanup(dev, &bridge_dev->bar);
>>>> +    }
>>>>      pci_bridge_exitfn(dev);
>>>>  }
>>>>  
>>>>  static void pci_bridge_dev_instance_finalize(Object *obj)
>>>>  {
>>>> +    /* this function is idempotent and handles (PCIDevice.shpc == NULL) */
>>>>      shpc_free(PCI_DEVICE(obj));
>>>>  }
>>>>  
>>>>  static void pci_bridge_dev_write_config(PCIDevice *d,
>>>>                                          uint32_t address, uint32_t val, 
>>>> int len)
>>>>  {
>>>> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(d);
>>>> +
>>>>      pci_bridge_write_config(d, address, val, len);
>>>>      if (msi_present(d)) {
>>>>          msi_write_config(d, address, val, len);
>>>>      }
>>>> -    shpc_cap_write_config(d, address, val, len);
>>>> +    if (hotplug_enabled(bridge_dev)) {
>>>> +        shpc_cap_write_config(d, address, val, len);
>>>> +    }
>>>>  }
>>>>  
>>>>  static void qdev_pci_bridge_dev_reset(DeviceState *qdev)
>>>>  {
>>>>      PCIDevice *dev = PCI_DEVICE(qdev);
>>>> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(dev);
>>>>  
>>>>      pci_bridge_reset(qdev);
>>>> -    shpc_reset(dev);
>>>> +    if (hotplug_enabled(bridge_dev)) {
>>>> +        shpc_reset(dev);
>>>> +    }
>>>>  }
>>>>  
>>>>  static Property pci_bridge_dev_properties[] = {
>>>>                      /* Note: 0 is not a legal chassis number. */
>>>>      DEFINE_PROP_UINT8("chassis_nr", PCIBridgeDev, chassis_nr, 0),
>>>>      DEFINE_PROP_BIT("msi", PCIBridgeDev, flags, PCI_BRIDGE_DEV_F_MSI_REQ, 
>>>> true),
>>>> +    DEFINE_PROP_BIT("hotplug", PCIBridgeDev, flags, 
>>>> PCI_BRIDGE_DEV_F_HOTPLUG,
>>>> +                    true),
>>>>      DEFINE_PROP_END_OF_LIST(),
>>>>  };
>>>>  
>>>> +static bool pci_bridge_dev_shpc_exists(void *opaque, int version_id)
>>>> +{
>>>> +    PCIDevice *dev = opaque;
>>>> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(dev);
>>>> +
>>>> +    return hotplug_enabled(bridge_dev);
>>>> +}
>>>> +
>>>>  static const VMStateDescription pci_bridge_dev_vmstate = {
>>>>      .name = "pci_bridge",
>>>>      .fields = (VMStateField[]) {
>>>>          VMSTATE_PCI_DEVICE(parent_obj, PCIBridge),
>>>> -        SHPC_VMSTATE(shpc, PCIDevice, NULL),
>>>> +        SHPC_VMSTATE(shpc, PCIDevice, pci_bridge_dev_shpc_exists),
>>>>          VMSTATE_END_OF_LIST()
>>>>      }
>>>>  };
>>>>  
>>>> +static void pci_bridge_dev_hotplug_cb(HotplugHandler *hotplug_dev,
>>>> +                                      DeviceState *dev, Error **errp)
>>>> +{
>>>> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(hotplug_dev);
>>>> +
>>>> +    if (!hotplug_enabled(bridge_dev)) {
>>>> +        error_setg(errp, "standard hotplug controller has been disabled 
>>>> for "
>>>> +                   "this %s", TYPE_PCI_BRIDGE_DEV);
>>>> +        return;
>>>> +    }
>>>> +    shpc_device_hotplug_cb(hotplug_dev, dev, errp);
>>>> +}
>>>> +
>>>> +static void pci_bridge_dev_hot_unplug_request_cb(HotplugHandler 
>>>> *hotplug_dev,
>>>> +                                                 DeviceState *dev,
>>>> +                                                 Error **errp)
>>>> +{
>>>> +    PCIBridgeDev *bridge_dev = PCI_BRIDGE_DEV(hotplug_dev);
>>>> +
>>>> +    if (!hotplug_enabled(bridge_dev)) {
>>>> +        error_setg(errp, "standard hotplug controller has been disabled 
>>>> for "
>>>> +                   "this %s", TYPE_PCI_BRIDGE_DEV);
>>>> +        return;
>>>> +    }
>>>> +    shpc_device_hot_unplug_request_cb(hotplug_dev, dev, errp);
>>>> +}
>>>> +
>>>>  static void pci_bridge_dev_class_init(ObjectClass *klass, void *data)
>>>>  {
>>>>      DeviceClass *dc = DEVICE_CLASS(klass);
>>>> @@ -154,8 +220,8 @@ static void pci_bridge_dev_class_init(ObjectClass 
>>>> *klass, void *data)
>>>>      dc->props = pci_bridge_dev_properties;
>>>>      dc->vmsd = &pci_bridge_dev_vmstate;
>>>>      set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
>>>> -    hc->plug = shpc_device_hotplug_cb;
>>>> -    hc->unplug_request = shpc_device_hot_unplug_request_cb;
>>>> +    hc->plug = pci_bridge_dev_hotplug_cb;
>>>> +    hc->unplug_request = pci_bridge_dev_hot_unplug_request_cb;
>>>>  }
>>>>  
>>>>  static const TypeInfo pci_bridge_dev_info = {
>>>> -- 
>>>> 1.8.3.1
>>>>