Re: Bug report: the extended PCI config space is missed with 6.2-rc2

[Bjorn Helgaas]

On Wed, Jan 04, 2023 at 09:39:56AM -0500, Liang, Kan wrote:
> Hi Bjorn,
> 
> Happy new year!
> 
> We found some PCI issues with the latest 6.2-rc2.
> 
> - Using the lspci -xxxx, the extended PCI config space of all PCI
> devices are missed with the latest 6.2-rc2. The system we used had 932
> PCI devices, at least 800 which have extended space as seen when booted
> into a 5.15 kernel. But none of them appeared in 6.2-rc2.
> - The drivers which rely on the information in the extended PCI config
> space don't work anymore. We have confirmed that the perf uncore driver
> (uncore performance monitoring) and Intel VSEC driver (telemetry) don't
> work in 6.2-rc2. There could be more drivers which are impacted.
> 
> After a bisect, we found the regression is caused by the below commit
> 07eab0901ede ("efi/x86: Remove EfiMemoryMappedIO from E820 map").
> After reverting the commit, the issues are gone.
> 
> Could you please take a look at the issues?

Certainly.  Can you capture the complete dmesg log, please?

Bjorn