Re: [PATCH v3] pci: correct pci config size default for cap version 2 endpoints

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* Alex Williamson (alex.williamson@xxxxxxxxxx) wrote:
> On Fri, 2011-07-22 at 14:24 -0700, Chris Wright wrote:
> > * Donald Dutile (ddutile@xxxxxxxxxx) wrote:
> > > diff --git a/hw/device-assignment.c b/hw/device-assignment.c
> > > index 36ad6b0..34db52e 100644
> > > --- a/hw/device-assignment.c
> > > +++ b/hw/device-assignment.c
> > > @@ -1419,16 +1419,18 @@ static int assigned_device_pci_cap_init(PCIDevice *pci_dev)
> > >      }
> > >  
> > >      if ((pos = pci_find_cap_offset(pci_dev, PCI_CAP_ID_EXP, 0))) {
> > > -        uint8_t version;
> > > +        uint8_t version, size;
> > >          uint16_t type, devctl, lnkcap, lnksta;
> > >          uint32_t devcap;
> > > -        int size = 0x3c; /* version 2 size */
> > >  
> > >          version = pci_get_byte(pci_dev->config + pos + PCI_EXP_FLAGS);
> > >          version &= PCI_EXP_FLAGS_VERS;
> > >          if (version == 1) {
> > >              size = 0x14;
> > > -        } else if (version > 2) {
> > > +        } else if (version == 2) {
> > > +            /* don't include slot cap/stat/ctrl 2 regs; only support endpoints */
> > > +            size = 0x34;
> > 
> > That doesn't look correct to me.  The size is fixed, just that some
> > registers are Reserved Zero when they do not apply (e.g. endpoint only).
> 
> Apparently it can be interpreted differently.  In this case, we've seen
> a tg3 device expose a v2 PCI express capability at offset 0xcc.  Using
> 0x3c bytes, we extend 8 bytes past the legacy config space area :(

Wow, that device sounds broken to me.  The spec is pretty clear.
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