Re: [Qemu-devel] [PATCH] pci: Error on PCI capability collisions

[Alex Williamson]

On Tue, 2011-08-23 at 21:17 +0300, Michael S. Tsirkin wrote:
> On Tue, Aug 23, 2011 at 07:28:08PM +0200, Jan Kiszka wrote:
> > From: Alex Williamson <address@hidden>
> > 
> > Nothing good can happen when we overlap capabilities
> > 
> > [ Jan: rebased over qemu, minor formatting ]
> > 
> > Signed-off-by: Jan Kiszka <address@hidden>
> 
> I'll stick an assert there instead. Normal devices
> don't generate overlapping caps unless there's a bug,
> and device assignment should do it's own checks.
> 
> I really have a mind to rip out the used array too.

So you'd rather kill qemu rather than have a reasonable error return
path... great :(

Alex

> > ---
> >  hw/pci.c |   14 ++++++++++++++
> >  1 files changed, 14 insertions(+), 0 deletions(-)
> > 
> > diff --git a/hw/pci.c b/hw/pci.c
> > index 6124790..ff20631 100644
> > --- a/hw/pci.c
> > +++ b/hw/pci.c
> > @@ -1952,11 +1952,25 @@ int pci_add_capability(PCIDevice *pdev, uint8_t 
> > cap_id,
> >                         uint8_t offset, uint8_t size)
> >  {
> >      uint8_t *config;
> > +    int i;
> > +
> >      if (!offset) {
> >          offset = pci_find_space(pdev, size);
> >          if (!offset) {
> >              return -ENOSPC;
> >          }
> > +    } else {
> > +        for (i = offset; i < offset + size; i++) {
> > +            if (pdev->used[i]) {
> > +                fprintf(stderr, "ERROR: %04x:%02x:%02x.%x "
> > +                        "Attempt to add PCI capability %x at offset "
> > +                        "%x overlaps existing capability %x at offset 
> > %x\n",
> > +                        pci_find_domain(pdev->bus), pci_bus_num(pdev->bus),
> > +                        PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn),
> > +                        cap_id, offset, pdev->config_map[i], i);
> > +                return -EFAULT;
> > +            }
> > +        }
> >      }
> >  
> >      config = pdev->config + offset;
> > -- 
> > 1.7.3.4