On Tue, Feb 24, 2015 at 11:10:33AM -0600, Bjorn Helgaas wrote:
>On Tue, Feb 24, 2015 at 3:00 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
>> On Tue, Feb 24, 2015 at 02:34:57AM -0600, Bjorn Helgaas wrote:
>>> From: Wei Yang <weiyang@xxxxxxxxxxxxxxxxxx>
>>>
>>> On PowerNV platform, resource position in M64 implies the PE# the resource
>>> belongs to. In some cases, adjustment of a resource is necessary to locate
>>> it to a correct position in M64.
>>>
>>> Add pnv_pci_vf_resource_shift() to shift the 'real' PF IOV BAR address
>>> according to an offset.
>>>
>>> [bhelgaas: rework loops, rework overlap check, index resource[]
>>> conventionally, remove pci_regs.h include, squashed with next patch]
>>> Signed-off-by: Wei Yang <weiyang@xxxxxxxxxxxxxxxxxx>
>>> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>>
>> ...
>>
>>> +#ifdef CONFIG_PCI_IOV
>>> +static int pnv_pci_vf_resource_shift(struct pci_dev *dev, int offset)
>>> +{
>>> + struct pci_dn *pdn = pci_get_pdn(dev);
>>> + int i;
>>> + struct resource *res, res2;
>>> + resource_size_t size;
>>> + u16 vf_num;
>>> +
>>> + if (!dev->is_physfn)
>>> + return -EINVAL;
>>> +
>>> + /*
>>> + * "offset" is in VFs. The M64 windows are sized so that when they
>>> + * are segmented, each segment is the same size as the IOV BAR.
>>> + * Each segment is in a separate PE, and the high order bits of the
>>> + * address are the PE number. Therefore, each VF's BAR is in a
>>> + * separate PE, and changing the IOV BAR start address changes the
>>> + * range of PEs the VFs are in.
>>> + */
>>> + vf_num = pdn->vf_pes;
>>> + for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
>>> + res = &dev->resource[i + PCI_IOV_RESOURCES];
>>> + if (!res->flags || !res->parent)
>>> + continue;
>>> +
>>> + if (!pnv_pci_is_mem_pref_64(res->flags))
>>> + continue;
>>> +
>>> + /*
>>> + * The actual IOV BAR range is determined by the start address
>>> + * and the actual size for vf_num VFs BAR. This check is to
>>> + * make sure that after shifting, the range will not overlap
>>> + * with another device.
>>> + */
>>> + size = pci_iov_resource_size(dev, i + PCI_IOV_RESOURCES);
>>> + res2.flags = res->flags;
>>> + res2.start = res->start + (size * offset);
>>> + res2.end = res2.start + (size * vf_num) - 1;
>>> +
>>> + if (res2.end > res->end) {
>>> + dev_err(&dev->dev, "VF BAR%d: %pR would extend past %pR (trying to enable %d VFs shifted by %d)\n",
>>> + i, &res2, res, vf_num, offset);
>>> + return -EBUSY;
>>> + }
>>> + }
>>> +
>>> + for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
>>> + res = &dev->resource[i + PCI_IOV_RESOURCES];
>>> + if (!res->flags || !res->parent)
>>> + continue;
>>> +
>>> + if (!pnv_pci_is_mem_pref_64(res->flags))
>>> + continue;
>>> +
>>> + size = pci_iov_resource_size(dev, i + PCI_IOV_RESOURCES);
>>> + res2 = *res;
>>> + res->start += size * offset;
>>
>> I'm still not happy about this fiddling with res->start.
>>
>> Increasing res->start means that in principle, the "size * offset" bytes
>> that we just removed from res are now available for allocation to somebody
>> else. I don't think we *will* give that space to anything else because of
>> the alignment restrictions you're enforcing, but "res" now doesn't
>> correctly describe the real resource map.
>>
>> Would you be able to just update the BAR here while leaving the struct
>> resource alone? In that case, it would look a little funny that lspci
>> would show a BAR value in the middle of the region in /proc/iomem, but
>> the /proc/iomem region would be more correct.
>
>I guess this would also require a tweak where we compute the addresses
>of each of the VF resources. Today it's probably just "base + VF_num
>* size", where "base" is res->start. We'd have to account for the
>offset there if we don't adjust it here.
>
Oh, this is really an interesting idea.
I will do some tests to see the result.
>>> +
>>> + dev_info(&dev->dev, "VF BAR%d: %pR shifted to %pR (enabling %d VFs shifted by %d)\n",
>>> + i, &res2, res, vf_num, offset);
>>> + pci_update_resource(dev, i + PCI_IOV_RESOURCES);
>>> + }
>>> + pdn->max_vfs -= offset;
>>> + return 0;
>>> +}
>>> +#endif /* CONFIG_PCI_IOV */
--
Richard Yang
Help you, Help me
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