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

[Ethan Zhao]

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