On 1/19/26 09:46, Jan Beulich wrote: > Legacy PCI devices don't have any extended config space. Reading any part > thereof may return all ones or other arbitrary data, e.g. in some cases > base config space contents repeatedly. > > Logic follows Linux 6.19-rc's pci_cfg_space_size(), albeit leveraging our > determination of device type; in particular some comments are taken > verbatim from there. > > Signed-off-by: Jan Beulich <[email protected]>
Reviewed-by: Stewart Hildebrand <[email protected]> > --- > Should we skip re-evaluation when pci_mmcfg_arch_enable() takes its early > exit path? I don't have a strong opinion here, though I'm leaning toward it's OK as is. > > The warning near the bottom of pci_check_extcfg() may be issued multiple > times for a single device now. Should we try to avoid that? If I'm reading Linux drivers/xen/pci.c correctly, my understanding is that dom0 will only invoke PHYSDEVOP_pci_mmcfg_reserved once per mmcfg segment, so in practice it's unlikely to spam. In other words, I think it's OK as is. > > Note that no vPCI adjustments are done here, but they're going to be > needed: Whatever requires extended capabilities will need re- > evaluating / newly establishing / tearing down in case an invocation of > PHYSDEVOP_pci_mmcfg_reserved alters global state. Agreed. The current patch is prerequisite for this work. Hm, perhaps we could create a gitlab ticket for it?
