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

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

On Wed, Mar 09, 2016 at 09:50:31AM -0700, Alex Williamson wrote:
> On Wed, 9 Mar 2016 18:22:24 +0200
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > On Mon, Mar 07, 2016 at 11:22:59AM +0800, Cao jin wrote:
> > > From: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> > > 
> > > Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>  
> > 
> > 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

I see. The name mislead me.  So what you want to do is validate a
multi-function device, not the bus.

> > > ---
> > >  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)

Is not it true that what you are really after is validating
functions of the given device?
Pls rename this pci_check_valid_functions or something
like this, and change it to only scan functions of the device,
not all devices on the bus.


> > > +{
> > > +    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
> > > 
> > >