Re: pci passthrough issue introduced between 4.14.1 and 4.15.0

[Jan Beulich <jbeulich@xxxxxxxx>]

On 01.06.2021 16:06, AL13N wrote:
> Jan Beulich schreef op 2021-06-01 12:08:
>> On 01.06.2021 09:36, AL13N wrote:
>>> Not 100% it's a bug or something i did wrong, but,
>>>
>>> with xl create i start a PV with 3 pci passthroughs
>>>
>>> after wards, xl pci-list shows all 3 nicely
>>>
>>> looking at the domU boot logs, pcifront is only creating one pci 
>>> device
>>> and lspci in the guest shows only 1 pci entry
>>>
>>> in at least 4.14.1 it still works.
>>
>> This reminds me of my report at
>> https://lists.xen.org/archives/html/xen-devel/2021-03/msg00956.html
>>
>> Meanwhile the proposed pciback change has gone in upstream:
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/xen/xen-pciback?id=c81d3d24602540f65256f98831d0a25599ea6b87
>>
>> I wasn't, however, aware that this may have been an issue going
>> from 4.14.1 to 4.15.0, i.e. something that was presumably (as
>> George also has just said) a regression in the tools. Or else I
>> probably wouldn't have suggested taking care of this in Linux.
>> Nevertheless you may want to give that change a try.
> 
> Well, both tests have only different tools en hypervisor, no kernel was 
> changed between both tests, neither in dom0 or domU , so, it might not 
> be pciback?

Well, if the problem was introduced in the tools and this having been
the reason for me running into the same or a similar issue, the patch
may still address the issue, even if - in case it's a regression in
the tools - it would have been better to also address the issue there.
As said, when analyzing the issue I didn't have indications of changed
tool stack behavior, i.e. I assumed the problem would have always been
there.

Jan