On 5/20/21 3:43 AM, Jan Beulich wrote: > On 20.05.2021 02:36, Boris Ostrovsky wrote: >> On 5/18/21 12:13 PM, Jan Beulich wrote: >>> >>> @@ -95,22 +95,25 @@ static int __xen_pcibk_add_pci_dev(struc >>> >>> /* >>> * Keep multi-function devices together on the virtual PCI bus, except >>> - * virtual functions. >>> + * that we want to keep virtual functions at func 0 on their own. They >>> + * aren't multi-function devices and hence their presence at func 0 >>> + * may cause guests to not scan the other functions. >> >> So your reading of the original commit is that whatever the issue it was, >> only function zero was causing the problem? In other words, you are not >> concerned that pci_scan_slot() may now look at function 1 and skip all >> higher-numbered function (assuming the problem is still there)? > I'm not sure I understand the question: Whether to look at higher numbered > slots is a function of slot 0's multi-function bit alone, aiui. IOW if > slot 1 is being looked at in the first place, slots 2-7 should also be > looked at.
Wasn't the original patch describing a problem strictly as one for single-function devices, so the multi-function bit is not set? I.e. if all VFs (which are single-function devices) are placed in the same slot then pci_scan_slot() would only look at function 0 and ignore anything higher-numbered. My question is whether it would "only look at function 0 and ignore anything higher-numbered" or "only look at the lowest-numbered function and ignore anything higher-numbered". -boris
