[WIP] Use pcie-pci-bridge for the same iommu group

[mikem-zed]

Rebase original PR https://github.com/lf-edge/eve/pull/2544

Here is the latest comment from @eriknordmark in the original PR

@mikem-zed is this sharing of address space something we can detect (from spec.sh or otherwise?) Our fallback position is that the hardware model needs to be tested and if it turns out that some devices must be assigned together then the user can edit the model file manually. (but if we have a way to detect it even better.)

We can detect address space overlapping by looking at BAR registers. It can be done at runtime. But this is exactly why Linux kernel put these devices into a single IOMMU group even with ACS override patch. Basically this check was already done by linux kernel. Are there any other reasons for putting >1 device in IOMMU group with ACS patch override? Good question. We can add a logic to check for address space overlaping and ad pci-pci bridge only in this case but the rule remains the same: the entier iommu group must be assigned to an app with or without extra pci-pci bridge

[OhmSpectator]

@rucoder, do you think we can convert the PR into a draft for now?

[rucoder]

@rucoder, do you think we can convert the PR into a draft for now?

I'd love to, but I do not have permissions, which is weird

[OhmSpectator]

Since #4394 is merged, this one is to be closed, I think.

[rene]

@rucoder , since https://github.com/lf-edge/eve/pull/4394 it's already merged, let's close this PR to avoid any confusion. At this point, it's better to provide new changes through a new PR...