On Thu, 2014-01-09 at 14:39 -0700, Bjorn Helgaas wrote: > On Thu, Jan 9, 2014 at 11:25 AM, Alex Williamson > <alex.williamson@xxxxxxxxxx> wrote: > > On Thu, 2014-01-09 at 11:08 -0700, Bjorn Helgaas wrote: > >> On Thu, Jan 9, 2014 at 8:36 AM, Alex Williamson > >> <alex.williamson@xxxxxxxxxx> wrote: > >> > Per the SR-IOV spec rev 1.1: > >> > > >> > 3.4.1.9 Header Type (Offset 0Eh) > >> > > >> > "... For VFs, this register must be RO Zero." > >> > > >> > Unfortunately some devices get this wrong, ex. Emulex OneConnect 10Gb > >> > NIC. When they do it makes us handle ACS testing and therefore IOMMU > >> > groups as if they were actual multifunction devices and require ACS > >> > capabilities to make sure there's no peer-to-peer between functions. > >> > VFs are never traditional multifunction devices, so simply clear this > >> > bit before we get any further into setup. > >> > >> This seems reasonable. Do you have "lspci -vvxxxx" output for this > >> device? I'd like to save it for future reference. > > > > Sure, here's a VF: > > > > 09:04.0 Ethernet controller: Emulex Corporation OneConnect 10Gb NIC (be3) (rev 01) > > Subsystem: Emulex Corporation Device e722 > > Thanks! I put this in > https://bugzilla.kernel.org/show_bug.cgi?id=68431, and I'll add a > reference to the changelog. > > But I wonder if we can make this slightly more generic by doing > something like this in pci_setup_device(): > > dev->multifunction = (PCI_FUNC(dev->devfn) == 0) && (hdr_type & 0x80); > > That's basically what lspci does in pci_generic_scan_bus(), and > section 3.2.2.3.4 of the PCI 3.0 spec sort of implies that we should > only look at the bit 7 of the header type for function 0: > > If a single function device is detected (i.e., bit 7 in the Header > Type register of function 0 is 0), no more functions for that > Device Number will be checked. If a multi-function device is > detected (i.e., bit 7 in the Header Type register of function 0 > is 1), then all remaining Function Numbers will be checked. We could do that and rely only on pci_scan_slot() to set multifunction=1 for the other functions, but that doesn't completely solve this problem. VFs can occupy function zero and the example device would still set multifunction with that test. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
