On Tue, 2022-08-02 at 09:46 +0200, Ard Biesheuvel wrote: > > If we want this, I would propose (happy to provide the implementation > > but let's discuss the design first) something along the line of a > > generic mechanism to "register" such a system device, which would add > > it to a list. That list would be scanned on PCI device discovery for > > BAR address matches, and the pci_dev/BAR# added to the entry (that or > > put a pointer to the entry into pci_dev for speed/efficiency). > > This means that bus numbers cannot be reassigned, which I don't think > we rely on today. To positively identify a PCI device, you'll need > some kind of path notation to avoid relying on the bus numbers > assigned by the firmware (this could happen for hot-pluggable root > ports where no bus range has been reserved by the firmware) That kind of path notation already exists for the Intel IOMMU, and probably others. See dmar_match_pci_path(), dmar_pci_bus_add_dev() etc. It would be good to lift that out and make it generic, rather than reinventing another version.
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