[edk2-devel] uefi VM and IO window overlap issue

[Gerd Hoffmann]

On Mon, Jun 12, 2023 at 07:27:37PM +0000, Kallol Biswas [C] wrote:
> Hi,
>     We have been observing an issue that IO BARs can't be claimed due to resource
> conflict.
> 
> [    0.457693] pci 0000:00:1d.0: can't claim BAR 4 [io  0x92a0-0x92bf]: address conflict with PCI Bus 0000:01 [io  0x9000-0x9fff]
> [    0.457705] pci 0000:00:1d.1: can't claim BAR 4 [io  0x9280-0x929f]: address conflict with PCI Bus 0000:01 [io  0x9000-0x9fff]
> [    0.457715] pci 0000:00:1d.2: can't claim BAR 4 [io  0x9260-0x927f]: address conflict with PCI Bus 0000:01 [io  0x9000-0x9fff]
> [    0.457743] pci 0000:00:1f.2: can't claim BAR 4 [io  0x9240-0x925f]: address conflict with PCI Bus 0000:01 [io  0x9000-0x9fff]
> [    0.457754] pci 0000:00:1f.3: can't claim BAR 4 [io  0x9200-0x923f]: address conflict with PCI Bus 0000:01 [io  0x9000-0x9fff]
> 
> 
> Please see the discussion thread:
> 
> https://www.spinics.net/lists/linux-pci/msg133740.html
> 
> The root of the problem is that OVMF does not take into account the limit register's granularity (limit) of a bridge,
> and programs EPs with overlapping IO ranges in a different bus.
> 
> Should we fix the issue in the OVMF?

IMHO yes.

https://edk2.groups.io/g/devel/message/96645

Jiewen suggested to fix it somewhere in PCI code instead.
No response from the PCI maintainers on that comment.

Jiewen, Ard?
How move forward with that?

take care,
  Gerd



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