On Mon, Nov 02, 2015 at 07:39:48AM -0800, Alexander Duyck wrote: >On 11/02/2015 12:27 AM, Wei Yang wrote: >>On Fri, Oct 30, 2015 at 09:03:54AM -0700, Alexander Duyck wrote: >>>On 10/29/2015 10:22 PM, Wei Yang wrote: >>>>On Thu, Oct 29, 2015 at 05:23:36PM -0500, Bjorn Helgaas wrote: >>>>>From: Alexander Duyck <[email protected]> >>>>> >>>>>VF bus numbers depend on the First VF Offset and VF Stride, and per >>>>>sections 3.3.9 and 3.3.10 of the SR-IOV spec r1.1, these depend on the >>>>>NumVF value. >>>>> >>>>>Wait until after we set NumVFs to compute and validate the bus number of >>>>>the last VF. >>>>> >>>>>[bhelgaas: changelog, add spec reference, split to separate patch for >>>>>reviewability] >>>>>Signed-off-by: Alexander Duyck <[email protected]> >>>>>Signed-off-by: Bjorn Helgaas <[email protected]> >>>>>--- >>>>>drivers/pci/iov.c | 18 ++++++++++-------- >>>>>1 file changed, 10 insertions(+), 8 deletions(-) >>>>> >>>>>diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c >>>>>index bd1c4fa..9d29712 100644 >>>>>--- a/drivers/pci/iov.c >>>>>+++ b/drivers/pci/iov.c >>>>>@@ -274,13 +274,6 @@ static int sriov_enable(struct pci_dev *dev, int >>>>>nr_virtfn) >>>>> return -ENOMEM; >>>>> } >>>>> >>>>>- bus = pci_iov_virtfn_bus(dev, nr_virtfn - 1); >>>>>- if (bus > dev->bus->busn_res.end) { >>>>>- dev_err(&dev->dev, "can't enable %d VFs (bus %02x out of range >>>>>of %pR)\n", >>>>>- nr_virtfn, bus, &dev->bus->busn_res); >>>>>- return -ENOMEM; >>>>>- } >>>>>- >>>>> if (pci_enable_resources(dev, bars)) { >>>>> dev_err(&dev->dev, "SR-IOV: IOV BARS not allocated\n"); >>>>> return -ENOMEM; >>>>>@@ -304,6 +297,15 @@ static int sriov_enable(struct pci_dev *dev, int >>>>>nr_virtfn) >>>>> } >>>>> >>>>> pci_iov_set_numvfs(dev, nr_virtfn); >>>>How about move it up? >>> >>>The idea with moving the write down is to keep the pollution of the SR-IOV >>>capability to a minimum. Basically we have addressed all of the possible >>>software issues at this point so all that remains is possible hardware >>>complications. In addition by moving this code down we only have to modify >>>this code instead of adding "rc=X; goto foo;" in places where "return X;" was >>>used. >>> >> >>I think your logic is clear, while it is not easy to classify the software >>issue and hardware complications. For example, at the beginning of >>sriov_enable(), the hardware value initial VFs number is checked. >> >>And in my mind, this is reasonable to check the hardware issue before software >>issue. >> >>For your comment, adding "rc=X; goto foo;", I don't see this would happen. >>The code in my mind would like this: >> >> >>+ pci_iov_set_numvfs(dev, nr_virtfn); >> bus = pci_iov_virtfn_bus(dev, nr_virtfn - 1); >> if (bus > dev->bus->busn_res.end) { >> dev_err(&dev->dev, "can't enable %d VFs (bus %02x out of range >> of %pR)\n", >> nr_virtfn, bus, &dev->bus->busn_res); >> return -ENOMEM; >> } >> >> if (pci_enable_resources(dev, bars)) { >> dev_err(&dev->dev, "SR-IOV: IOV BARS not allocated\n"); >> return -ENOMEM; >> >>Do I missed something? > >The problem is that pci_iov_set_numvfs has side effects visible to the user >since they can read NumVFs lspci and via sysfs. As such we want to keep the >two in sync, and if you get the bus error here that is not the case. > >That is why you must call pci_iov_set_numvfs(dev, 0) if this fails. >
That's the reason. Thanks for letting me know :-) >- Alex -- Richard Yang Help you, Help me -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
