Re: ARI and igb emulation

[Ani Sinha]

> On 28-Jun-2023, at 6:15 PM, Akihiko Odaki <akihiko.odaki@daynix.com> wrote:
> 
> Adding CC.
> 
> On 2023/06/28 21:24, Akihiko Odaki wrote:
>> On 2023/06/27 23:32, Ani Sinha wrote:
>>> Hi :
>>> I am proposing a patch in QEMU [1] which may or may not break ARI but I 
>>> wanted to give my best shot in making sure I am not breaking anything with 
>>> ARI enabled. I see that your igb emulation code enables ARI with its SRIOV 
>>> emulation. I ran the qtest and avocado tests that are mentioned in [2] and 
>>> they both pass. Is there anything else/any tweaks that I should be doing to 
>>> make sure I am not breaking ARI with igb?
>>> 
>>> Thanks for information,
>>> Ani
>>> 
>>> 1. https://lists.gnu.org/archive/html/qemu-devel/2023-06/msg05478.html
>>> 2. https://www.qemu.org/docs/master/system/devices/igb.html
>>> 
>>> 
>> This indeed resulted in the following error message with igb:
>> qemu-system-aarch64: PCI: slot 16 is not valid for igbvf, parent device only 
>> allows plugging into slot 0.
>> To reproduce the issue, add the following to QEMU command line:
>> -device pcie-root-port,id=p -device igb,bus=p
>> And enable 7 virtual functions on the guest. For Linux, see:
>> https://docs.kernel.org/PCI/pci-iov-howto.html
>> You may only enforce the slot number restriction only for devices without 
>> ARI. The slot number is assumed as 0 when ARI is enabled if I understand 
>> correctly.

So I guess mst was correct as to the reason why the previous conditional checks 
for !vf :-) Very interesting!