Re: [Qemu-devel] [patch v5 07/12] pci: add a pci_function_is_valid callback to check function if valid

[Alex Williamson <alex.williamson@redhat.com>]

On Wed, 23 Mar 2016 18:12:02 +0800
Cao jin <caoj.fnst@cn.fujitsu.com> wrote:

> From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> 
> PCI hotplug requires that function 0 is added last to close the
> slot.  Since vfio supporting AER, we require that the VM bus
> contains the same set of devices as the host bus to support AER,
> we can perform an AER validation test whenever a function 0 in
> the VM is hot-added.
> 
> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> ---
>  hw/pci/pci.c         | 32 ++++++++++++++++++++++++++++++++
>  include/hw/pci/pci.h |  1 +
>  2 files changed, 33 insertions(+)


This would of course need Michael's ack.

Michael, we can't do this in vfio-pci code because we can't guarantee
that function 0 is a vfio-pci device.  That would allow users to bypass
our configuration requirements by putting any random non-vfio-pci
device at function 0 of a hot-added multifunction device.

> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index e67664d..2a5291a 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -1840,6 +1840,22 @@ PCIDevice *pci_find_device(PCIBus *bus, int bus_num, uint8_t devfn)
>      return bus->devices[devfn];
>  }
>  
> +static void pci_function_is_valid(PCIBus *bus, PCIDevice *d, void *opaque)
> +{
> +    PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(d);
> +    Error **errp = opaque;
> +
> +    if (*errp) {
> +        return;
> +    }
> +
> +    if (!pc->is_valid_func) {
> +        return;
> +    }
> +
> +    pc->is_valid_func(d, errp);
> +}
> +
>  static void pci_qdev_realize(DeviceState *qdev, Error **errp)
>  {
>      PCIDevice *pci_dev = (PCIDevice *)qdev;
> @@ -1882,6 +1898,22 @@ static void pci_qdev_realize(DeviceState *qdev, Error **errp)
>          pci_qdev_unrealize(DEVICE(pci_dev), NULL);
>          return;
>      }
> +
> +    /*
> +     *  If the function number is 0, indicate the closure of the slot.
> +     *  then we get the chance to check all functions on same device
> +     *  if valid.
> +     */
> +    if (DEVICE(pci_dev)->hotplugged &&
> +        pci_get_function_0(pci_dev) == pci_dev) {
> +        pci_for_each_device(bus, pci_bus_num(bus),
> +                            pci_function_is_valid, &local_err);
> +        if (local_err) {
> +            error_propagate(errp, local_err);
> +            pci_qdev_unrealize(DEVICE(pci_dev), NULL);
> +            return;
> +        }
> +    }
>  }
>  
>  static void pci_default_realize(PCIDevice *dev, Error **errp)
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index 0be07c8..4a2f7d4 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -190,6 +190,7 @@ typedef struct PCIDeviceClass {
>  
>      void (*realize)(PCIDevice *dev, Error **errp);
>      int (*init)(PCIDevice *dev);/* TODO convert to realize() and remove */
> +    void (*is_valid_func)(PCIDevice *dev, Error **errp);
>      PCIUnregisterFunc *exit;
>      PCIConfigReadFunc *config_read;
>      PCIConfigWriteFunc *config_write;