On Tuesday, May 05, 2015 07:15:21 PM Ryan Stone wrote: > On Tue, May 5, 2015 at 9:17 AM, Eric Badger <eric_bad...@dell.com> wrote: > > > Hi Ryan and -current, > > > > During IOV config, when setting up VF bars, several calls are made to > > 'pci_read_bar' (in sys/dev/pci/pci.c) in order to size VF BARs, which > > causes memory decoding to be turned off temporarily for the PF associated > > with those VFs. I'm finding that this can interfere with an already running > > PF. > > > > Ouch. That's a nasty bug. Thanks for tracking this down. > > > > 1. Check the value of the 'reg' arg to 'pci_read_bar' and, if it is > > outside a standard BAR range, don't disable memory decoding. This is > > simple, but feels a little hackish and may have consequences I'm missing. > > > 2. Pass some flag/context through such that pci_read_bar knows it is > > configuring VF BARs (we might instead disable VF MSE in this case, if it is > > enabled). It would be necessary to carry this flag/context through several > > function calls before reaching pci_read_bar, which might end up being ugly. > > > 3. Rearrange the calls so that VF BARs are sized when the PF is not yet > > running, and that info saved until VFs are created. Probably it would be > > done when the PF BARs are sized for any device supporting IOV, even if that > > device never creates VFs. > > > > I don't think that #3 is possible. Unfortunately the BAR is sized again > when the BAR is allocated so it's difficult so it wouldn't be enough to > just size the BAR during attach. I would have to reserve the memory space > during attach, but that might reserve physical address space that other > devices need to function. > > Actually, that problem will prevent #2 from being easy to implement too. > We'd have to add an extra flag to pci_alloc_multi_resource. I think that > #1 is the best option. There's already a precedent for something similar > has it has a special base for the device ROM BAR. > > I haven't had a chance to test this yet, but I believe that this patch will > solve the problem: > > https://people.freebsd.org/~rstone/patches/iov_bar.diff
There are some devices with BARs in non-standard locations. :( If there is a flag to just disable the VF bar decoding, then ideally we should just be doing that and leaving the global decoding flag alone while sizing the VF BAR. -- John Baldwin _______________________________________________ firstname.lastname@example.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"