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

[Laszlo Ersek <lersek@redhat.com>]

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

Should I also rename the helper function hotplug_enabled() to
shpc_enabled()?

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
>>