On 31/08/17 05:02, Bjorn Helgaas wrote: > On Fri, Aug 11, 2017 at 06:19:33PM +1000, Alexey Kardashevskiy wrote: >> From: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx> >> >> The PowerNV platform is the only user of pcibios_sriov_disable(). >> The IOV BAR could be shifted by pci_iov_update_resource(). The >> warning message in the function is printed if the IOV capability >> is in enabled (PCI_SRIOV_CTRL_VFE && PCI_SRIOV_CTRL_MSE) state. >> >> This is the backtrace of what is happening: >> pci_disable_sriov >> sriov_disable >> pnv_pci_sriov_disable >> pnv_pci_vf_resource_shift >> pci_update_resource >> pci_iov_update_resource >> >> This fixes the issue by disabling IOV capability before calling >> pcibios_sriov_disable(). With it, the disabling path matches >> the enabling path: pcibios_sriov_enable() is called before the >> IOV capability is enabled. >> >> Cc: shan.gavin@xxxxxxxxx >> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> >> Cc: Paul Mackerras <paulus@xxxxxxxxx> >> Reported-by: Carol L Soto <clsoto@xxxxxxxxxx> >> Signed-off-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx> >> Tested-by: Carol L Soto <clsoto@xxxxxxxxxx> >> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx> >> --- >> >> This is repost. Since Gavin left the team, I am trying to push it out. >> The previos converstion is here: https://patchwork.ozlabs.org/patch/732653/ > > I gave up on the previous issue. I think this patch makes sense as-is > at least as far as the fact that we can't update a struct resource > while the device is still consuming it. I reworked the changelog to > emphasize that. > > I assume the fact that pci_iov_update_resource() dropped the resource > update caused some user-visible issue later on, and I might mention > that, too, if I knew what it was. I could not identify any issue so far in my test setup - I recreated VFs several times, run some traffic through them on one of mellanox'es so the message+backtrace seems to be the only issue for now. > Here's what I would consider putting on pci/virtualization (the diff > is unchanged from your post): This sounds good to me, thanks for updating the commit log. I'll still try and finish my homework with updating that comment about the hole in arch/powerpc/platforms/powernv/pci-ioda.c. Cheers. > > > commit 08132e7759b3929bea0ccdf8afe81ebf05351389 > Author: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx> > Date: Fri Aug 11 18:19:33 2017 +1000 > > PCI: Disable VF decoding before updating resources in pcibios_sriov_disable() > > A struct resource represents the address space consumed by a device. We > should not modify that resource while the device is actively using the > address space. For VFs, pci_iov_update_resource() enforces this by > printing a warning and doing nothing if the VFE (VF Enable) and MSE (VF > Memory Space Enable) bits are set. > > Previously, both sriov_enable() and sriov_disable() called the > pcibios_sriov_disable() arch hook, which may update the struct resource, > while VFE and MSE were enabled. This effectively dropped the resource > update pcibios_sriov_disable() intended to do. > > Disable VF memory decoding before calling pcibios_sriov_disable(). > > Reported-by: Carol L Soto <clsoto@xxxxxxxxxx> > Tested-by: Carol L Soto <clsoto@xxxxxxxxxx> > Signed-off-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx> > [bhelgaas: changelog] > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > Cc: shan.gavin@xxxxxxxxx > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > Cc: Paul Mackerras <paulus@xxxxxxxxx> > > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c > index 120485d6f352..ac41c8be9200 100644 > --- a/drivers/pci/iov.c > +++ b/drivers/pci/iov.c > @@ -331,7 +331,6 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn) > while (i--) > pci_iov_remove_virtfn(dev, i, 0); > > - pcibios_sriov_disable(dev); > err_pcibios: > iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE); > pci_cfg_access_lock(dev); > @@ -339,6 +338,8 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn) > ssleep(1); > pci_cfg_access_unlock(dev); > > + pcibios_sriov_disable(dev); > + > if (iov->link != dev->devfn) > sysfs_remove_link(&dev->dev.kobj, "dep_link"); > > @@ -357,14 +358,14 @@ static void sriov_disable(struct pci_dev *dev) > for (i = 0; i < iov->num_VFs; i++) > pci_iov_remove_virtfn(dev, i, 0); > > - pcibios_sriov_disable(dev); > - > iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE); > pci_cfg_access_lock(dev); > pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl); > ssleep(1); > pci_cfg_access_unlock(dev); > > + pcibios_sriov_disable(dev); > + > if (iov->link != dev->devfn) > sysfs_remove_link(&dev->dev.kobj, "dep_link"); > > -- Alexey
