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

Alex Williamson
2011-07-22T21:30:35Z

On Fri, 2011-07-22 at 14:24 -0700, Chris Wright wrote:
> * Donald Dutile (ddutile@redhat.com) 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 :(

Alex