On Wed, Mar 30, 2022 at 02:10:17PM -0500, Bjorn Helgaas wrote: > On Wed, Mar 30, 2022 at 12:37:20PM -0300, Jason Gunthorpe wrote: > > On Wed, Mar 30, 2022 at 05:08:23PM +0300, Shlomo Pongratz wrote: > > > @@ -350,7 +353,10 @@ static struct pci_dev *pci_host_bridge_dev(struct pci_host_bridge *host) > > > > > > if (!root) > > > return NULL; > > > - if (root->devfn != PCI_DEVFN(0, 0)) > > > + > > > + /* Is it a host bridge or a root port? */ > > > > This is a better comment: > > > > /* host bridges must have a 0 devfn, but some of the entries in the > > whilelist are root ports that can have any devfn */ > > Is this something in the spec or is it just common practice? The PCIe > spec says very little about "host bridges" and I don't remember > anything about them having to be devfn 0 or even that they have to be > materialized as PCI devices. I think we are relying on common practice here, but I don't know why this check was added in the first place? Logan? Jason
