On Fri, Feb 20, 2015 at 05:47:09PM -0600, Bjorn Helgaas wrote: >On Tue, Feb 10, 2015 at 07:14:45PM +1100, Benjamin Herrenschmidt wrote: >> On Tue, 2015-02-10 at 14:25 +0800, Wei Yang wrote: >> > PF's resource will be assigned first, including normal BARs and IOV >> > BARs. >> > >> > Then PF's driver will create VFs, in virtfn_add(). In this function, >> > VF's >> > resources is calculated from its PF's IOV BAR. >> > >> > If you reset VF's resource as PFs, no one will try to assign it again. >> >> So the problem is that the flag indicating VF is lost ? IE. We should >> still mark them unset, but preserve that flag ? > >I think the problem is that the normal path for PCI_REASSIGN_ALL_RSRC is >at boot-time, where we do this: > > pcibios_init > pcibios_scan_phb > pci_scan_child_bus > ... > pci_device_add > pci_fixup_device(pci_fixup_header) > pcibios_fixup_resources # header fixup > for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) > dev->resource[i].start = 0 > pcibios_resource_survey > pcibios_allocate_resources > >and we assign dev->resource[] for everything in >pcibios_allocate_resources(). > >But VFs are enumerated later, when they are enabled by the PF driver after >boot, so we have this path: > > pci_enable_sriov > sriov_enable > virtfn_add(vf_id) > for (i = 0; i < 6; i++) > vf->resource[i].start = pf->resource[IOV + i].start + (size * vf_id) > pci_device_add > pci_fixup_device(pci_fixup_header) > pcibios_fixup_resources # header fixup > for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) > vf->resource[i].start = 0 > >Here, we clear out vf->resource[0..5] in the header fixup, but we're not >going to call pcibios_allocate_resources() again to reassign them. > >So I think the *intent* of PCI_REASSIGN_ALL_RSRC is preserved if >pcibios_fixup_resources() leaves the VF resources alone, because the VF >resources are completely determined by the PF resources, and the PF >resources have already been reassigned. > >If my understanding is correct, I think the patch is reasonable, and I >would try to put some of this explanation into the changelog. Yep, it is correct, thanks for your explanation. I did a chat on IRC with Ben, I guess he has got the idea :-) > >Bjorn -- Richard Yang Help you, Help me -- 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
