Re: [Qemu-devel] [PATCH] pci: Return PCI_INTX_DISABLED when no bus INTx routing support

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

On Wed, Oct 17, 2012 at 08:40:05PM +0200, Jan Kiszka wrote:
> On 2012-10-17 20:25, Alex Williamson wrote:
> > Rather than assert, simply return PCI_INTX_DISABLED when we don't
> > have a pci_route_irq_fn.  PIIX already returns DISABLED for an
> > invalid pin, so users already deal with this state.  Users of this
> > interface should only be acting on an ENABLED or INVERTED return
> > value (though we really have no support for INVERTED).
> > 
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > ---
> > 
> > A compromise to the gridlock; defuse the assert, but don't add
> > a new state to the API.  Thanks,
> 
> But how do you tell "unsupported" apart from "disabled" in VFIO? If the
> chipset truly disabled the line, you must not provide it to the guest in
> some other way.
> 
> Jan

vfio does not care. It merely disables irqfd and delivers irqs to qemu.

> > 
> > Alex
> > 
> >  hw/pci.c |    6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/pci.c b/hw/pci.c
> > index 83d262a..9525220 100644
> > --- a/hw/pci.c
> > +++ b/hw/pci.c
> > @@ -1094,7 +1094,11 @@ PCIINTxRoute pci_device_route_intx_to_irq(PCIDevice *dev, int pin)
> >           pin = bus->map_irq(dev, pin);
> >           dev = bus->parent_dev;
> >      } while (dev);
> > -    assert(bus->route_intx_to_irq);
> > +
> > +    if (!bus->route_intx_to_irq) {
> > +        return (PCIINTxRoute) { PCI_INTX_DISABLED, -1 };
> > +    }
> > +
> >      return bus->route_intx_to_irq(bus->irq_opaque, pin);
> >  }
> >  
> > 
> 
> -- 
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