Hi Ben, On Thu, Oct 08, 2015 at 10:20:17AM -0500, Ben Shelton wrote: > For some SR-IOV devices, the number of available virtual functions increases > after enabling ARI. Currently, SRIOV_NUM_VF is read and saved off before the > ARI control bit is enabled in SRIOV_CTRL. This causes an issue when VFs are > enabled. > > At device init, SRIOV_INITIAL_VF and SRIOV_NUM_VF are specified to contain the > number of available VFs for the device. sriov_enable() does a sanity check > that SRIOV_INITIAL_VF is not greater than iov->total_VFs, the saved-off value > of SRIOV_NUM_VF. Since the value of both SRIOV_INITIAL_VF and SRIOV_NUM_VF has > increased after enabling the ARI bit, the check fails, and the VFs cannot be > enabled. > > To fix the issue, write SRIOV_CTRL first, and then read SRIOV_NUM_VF. I think you mean PCI_SRIOV_TOTAL_VR (not NUM_VF), right? This is interesting because the spec says TotalVFs is HwInit, which means it's read-only, and it doesn't mention anything about it changing when ARIis enabled. I can see why it would change in that case, so maybe this is just a goof in the spec. Bjorn > Signed-off-by: Ben Shelton <benjamin.h.shelton@xxxxxxxxx> > --- > > Changes since v1: > * Moved read of SRIOV_NUM_VF rather than re-reading it if ARI was enabled. > > drivers/pci/iov.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c > index ee0ebff..0174044 100644 > --- a/drivers/pci/iov.c > +++ b/drivers/pci/iov.c > @@ -399,10 +399,6 @@ static int sriov_init(struct pci_dev *dev, int pos) > ssleep(1); > } > > - pci_read_config_word(dev, pos + PCI_SRIOV_TOTAL_VF, &total); > - if (!total) > - return 0; > - > ctrl = 0; > list_for_each_entry(pdev, &dev->bus->devices, bus_list) > if (pdev->is_physfn) > @@ -414,6 +410,11 @@ static int sriov_init(struct pci_dev *dev, int pos) > > found: > pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl); > + > + pci_read_config_word(dev, pos + PCI_SRIOV_TOTAL_VF, &total); > + if (!total) > + return 0; > + > pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, 0); > pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset); > pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride); > -- > 1.9.5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
