Re: [Qemu-devel] [PATCH v13 09/13] add check reset mechanism when hotplug vfio device

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

On Wed, Nov 11, 2015 at 06:34:27PM +0800, Cao jin wrote:
> From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> 
> Since we support multi-function hotplug. the function 0 indicate
> the closure of the slot, so we have the chance to do the check.
> 
> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> ---
>  hw/pci/pci.c             | 29 +++++++++++++++++++++++++++++
>  hw/vfio/pci.c            | 19 +++++++++++++++++++
>  hw/vfio/pci.h            |  2 ++
>  include/hw/pci/pci_bus.h |  5 +++++
>  4 files changed, 55 insertions(+)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 168b9cc..f6ca6ef 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -81,6 +81,7 @@ static void pci_bus_realize(BusState *qbus, Error **errp)
>      PCIBus *bus = PCI_BUS(qbus);
>  
>      vmstate_register(NULL, -1, &vmstate_pcibus, bus);
> +    notifier_with_return_list_init(&bus->hotplug_notifiers);
>  }
>  
>  static void pci_bus_unrealize(BusState *qbus, Error **errp)
> @@ -1835,6 +1836,22 @@ PCIDevice *pci_find_device(PCIBus *bus, int bus_num, uint8_t devfn)
>      return bus->devices[devfn];
>  }
>  
> +void pci_bus_add_hotplug_notifier(PCIBus *bus, NotifierWithReturn *notify)
> +{
> +    notifier_with_return_list_add(&bus->hotplug_notifiers, notify);
> +}
> +
> +void pci_bus_remove_hotplug_notifier(NotifierWithReturn *notifier)
> +{
> +    notifier_with_return_remove(notifier);
> +}
> +
> +static int pci_bus_hotplug_notifier(PCIBus *bus, void *opaque)
> +{
> +    return notifier_with_return_list_notify(&bus->hotplug_notifiers,
> +                                            opaque);
> +}
> +
>  static void pci_qdev_realize(DeviceState *qdev, Error **errp)
>  {
>      PCIDevice *pci_dev = (PCIDevice *)qdev;
> @@ -1877,6 +1894,18 @@ static void pci_qdev_realize(DeviceState *qdev, Error **errp)
>          pci_qdev_unrealize(DEVICE(pci_dev), NULL);
>          return;
>      }
> +
> +    /*
> +     *  If the function is func 0, indicate the closure of the slot.
> +     *  signal the callback.
> +     */
> +    if (DEVICE(pci_dev)->hotplugged &&
> +        pci_get_function_0(pci_dev) == pci_dev &&
> +        pci_bus_hotplug_notifier(bus, pci_dev)) {
> +        error_setg(errp, "failed to hotplug function 0");
> +        pci_qdev_unrealize(DEVICE(pci_dev), NULL);
> +        return;
> +    }

I don't understand why this is required in pci core.
PCI Device is already constructed anyway.
Just do the checks and call unrealize in vfio.

I also don't see why you are tying this to hotplug.
I would check each function as it's added.
But that's a vfio thing, if both you and Alex think
it's a good idea, fine by me.

>  }
>  
>  static void pci_default_realize(PCIDevice *dev, Error **errp)
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 31ffd44..e619998 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -1990,6 +1990,19 @@ static int vfio_check_devices_host_bus_reset(void)
>      return 0;
>  }
>  
> +static int vfio_check_bus_reset(NotifierWithReturn *n, void *opaque)
> +{
> +    VFIOPCIDevice *vdev = container_of(n, VFIOPCIDevice, hotplug_notifier);
> +    PCIDevice *pci_dev = PCI_DEVICE(vdev);
> +    PCIDevice *pci_func0 = opaque;
> +
> +    if (pci_get_function_0(pci_dev) != pci_func0) {
> +        return 0;
> +    }
> +
> +    return vfio_check_host_bus_reset(vdev);
> +}
> +
>  static int vfio_setup_aer(VFIOPCIDevice *vdev, uint8_t cap_ver,
>                            int pos, uint16_t size)
>  {
> @@ -2044,6 +2057,9 @@ static int vfio_setup_aer(VFIOPCIDevice *vdev, uint8_t cap_ver,
>          return ret;
>      }
>  
> +    vdev->hotplug_notifier.notify = vfio_check_bus_reset;
> +    pci_bus_add_hotplug_notifier(pdev->bus, &vdev->hotplug_notifier);
> +
>      return 0;
>  
>  error:
> @@ -2919,6 +2935,9 @@ static void vfio_exitfn(PCIDevice *pdev)
>      vfio_unregister_req_notifier(vdev);
>      vfio_unregister_err_notifier(vdev);
>      pci_device_set_intx_routing_notifier(&vdev->pdev, NULL);
> +    if (vdev->features & VFIO_FEATURE_ENABLE_AER) {
> +        pci_bus_remove_hotplug_notifier(&vdev->hotplug_notifier);
> +    }
>      vfio_disable_interrupts(vdev);
>      if (vdev->intx.mmap_timer) {
>          timer_free(vdev->intx.mmap_timer);
> diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
> index 59ae194..b385f07 100644
> --- a/hw/vfio/pci.h
> +++ b/hw/vfio/pci.h
> @@ -142,6 +142,8 @@ typedef struct VFIOPCIDevice {
>      bool no_kvm_intx;
>      bool no_kvm_msi;
>      bool no_kvm_msix;
> +
> +    NotifierWithReturn hotplug_notifier;
>  } VFIOPCIDevice;
>  
>  uint32_t vfio_pci_read_config(PCIDevice *pdev, uint32_t addr, int len);
> diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
> index 403fec6..7812fa9 100644
> --- a/include/hw/pci/pci_bus.h
> +++ b/include/hw/pci/pci_bus.h
> @@ -39,8 +39,13 @@ struct PCIBus {
>         Keep a count of the number of devices with raised IRQs.  */
>      int nirq;
>      int *irq_count;
> +
> +    NotifierWithReturnList hotplug_notifiers;
>  };
>  
> +void pci_bus_add_hotplug_notifier(PCIBus *bus, NotifierWithReturn *notify);
> +void pci_bus_remove_hotplug_notifier(NotifierWithReturn *notify);
> +
>  typedef struct PCIBridgeWindows PCIBridgeWindows;
>  
>  /*
> -- 
> 1.9.3