Re: [PATCH v4] Subject: PCI: Enable io space 1k granularity for intel cpu root port

Ethan Zhao
2024-07-24T05:39:58Z

On 7/24/2024 11:38 AM, Zhou Shengqing wrote:
>> On 7/23/2024 4:04 PM, Zhou Shengqing wrote:
>>>> I think this has potential. Can you include a more complete citation
>>>> for the Intel spec? Complete name, document number if available,
>>>> revision, section? Hopefully it's publically available?
>>> Most of intel CPU EDS specs are under NDA. But you can refer to
>>> https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/xeon-e5-v2-datasheet-vol-2.pdf
>>> keyword:"EN1K".
>>> ...
>>>
>>> while ((d = pci_get_device(PCI_VENDOR_ID_INTEL, 0x09a2, d))) {
>>> if (pci_domain_nr(d->bus) == pci_domain_nr(dev->bus)) {
>> Perhaps it is enough to check if the 0x09a2 VT-d and the rootport are on the smae bus
>> e.g. On my SPR, domain 0000
> Thank you for your comment.
>
> Do you mean it shoud be like this?
>
> while ((d = pci_get_device(PCI_VENDOR_ID_INTEL, 0x09a2, d))) {
> if (d->bus->number == dev->bus->number) {
> pci_read_config_word(d, 0x1c0, &en1k);
> if (en1k & 0x4) {
> pci_info(dev, "1K I/O windows enabled per %s EN1K setting\n", pci_name(d));
> dev->io_window_1k = 1;
> }
> }
> }
>
>> 00:00.0 System peripheral: Intel Corporation Device 09a2 (rev 20)
>> 00:0f.0 PCI bridge: Intel Corporation Device 1bbf (rev 10) (prog-if 00 [Normal decode])
>>
>>
>> 15:00.0 System peripheral: Intel Corporation Device 09a2 (rev 20)
>> 15:01.0 PCI bridge: Intel Corporation Device 352a (rev 04) (prog-if 00 [Normal decode])
>>
>> and if you check domain number only, they might sit on different bus, perhaps that
>> would make thing complex, could you make sure the VT-d is on the upstream bus of the
>> bridge ?
> I checked it on ICX SPR EMR GNR, VT-d is always on the same bus with root port,
> and VT-d device and function number is always 0.

Yes, every VT-d instance in the root complex and the root port integrated are
on the same bus. and VT-d is the first device of that bus.

The EDS doesn't say if there is exception one of the VT-d instances in an
system its EN1K wasn't set while others were set, vice vesa. so I suggest
just check the VT-d and then set the root port's io_windows_1k of the same bus.

Hope that works for your case.

Thanks,
Ethan

>
> Please let me know if further modifications are needed.
>
>> Thanks,
>> Ethan