Re: [Qemu-devel] [PATCH v2 06/11] pci: add a is_valid_func callback to check device if complete

[Alex Williamson]

On Wed, 9 Mar 2016 18:22:24 +0200
"Michael S. Tsirkin" <address@hidden> wrote:

> On Mon, Mar 07, 2016 at 11:22:59AM +0800, Cao jin wrote:
> > From: Chen Fan <address@hidden>
> > 
> > Signed-off-by: Chen Fan <address@hidden>  
> 
> So if you create a mess, you discover it when
> you later add function 0.
> Why not call this when function is added?
> O(N^2) on # of functions, but that # is up to 256 so maybe
> that is not too bad.

Because the configuration isn't valid until the slot is closed.  Take a
dual port NIC example again, after we add the first function, the
configuration is invalid because we have an AER indicated device that
can't do a bus reset because the second function, which may be in a
separate IOMMU group, hasn't been added yet.  Therefore we can only
check the configuration when the slot is complete.  Thanks,

Alex
 
> > ---
> >  hw/pci/pci.c         | 39 +++++++++++++++++++++++++++++++++++++++
> >  include/hw/pci/pci.h |  1 +
> >  2 files changed, 40 insertions(+)
> > 
> > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > index d940f79..72650c5 100644
> > --- a/hw/pci/pci.c
> > +++ b/hw/pci/pci.c
> > @@ -1836,6 +1836,31 @@ PCIDevice *pci_find_device(PCIBus *bus, int bus_num, 
> > uint8_t devfn)
> >      return bus->devices[devfn];
> >  }
> >  
> > +static void pci_bus_check_device(PCIDevice *pdev, Error **errp)
> > +{
> > +    PCIBus *bus = pdev->bus;
> > +    PCIDeviceClass *pc;
> > +    int i;
> > +    Error *local_err = NULL;
> > +
> > +    for (i = 0; i < ARRAY_SIZE(bus->devices); ++i) {
> > +        if (!bus->devices[i]) {
> > +            continue;
> > +        }
> > +
> > +        pc = PCI_DEVICE_GET_CLASS(bus->devices[i]);
> > +        if (!pc->is_valid_func) {
> > +            continue;
> > +        }
> > +
> > +        pc->is_valid_func(bus->devices[i], &local_err);
> > +        if (local_err) {
> > +            error_propagate(errp, local_err);
> > +            return;
> > +        }
> > +    }
> > +}
> > +
> >  static void pci_qdev_realize(DeviceState *qdev, Error **errp)
> >  {
> >      PCIDevice *pci_dev = (PCIDevice *)qdev;
> > @@ -1878,6 +1903,20 @@ 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.
> > +     *  then we get the chance to check all functions on same device
> > +     *  if valid.
> > +     */
> > +    if (pci_get_function_0(pci_dev) == pci_dev) {
> > +        pci_bus_check_device(pci_dev, &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 dedf277..4e56256 100644
> > --- a/include/hw/pci/pci.h
> > +++ b/include/hw/pci/pci.h
> > @@ -191,6 +191,7 @@ 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;
> > -- 
> > 1.9.3
> > 
> >