On Fri, Aug 18, 2017 at 08:05:42AM +1000, Alexey Kardashevskiy wrote: > On 11/08/17 18:19, 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/ > > > > Two questions were raised then. I'll try to comment on this below. > > Bjorn, ping? Thanks. Thanks for the reminder. This is in patchwork, so it's on my to-do list. My last response in the thread above was: I'm not going to merge this without a comment in pnv_pci_vf_resource_shift() that addresses the two questions I raised in my very first response. I don't think the existing comment about "After doing so, there would be a 'hole'" is sufficient. If it were sufficient, I wouldn't have raised the questions in the first place. The problem here is that I'm looking for a comment *in the code*, and you and Gavin are giving responses and clarifications in email. What we need to do is transfer this email information into something useful when reading the code, i.e., a comment in the code. > >> 1) "res" is already in the resource tree, so we shouldn't be changing > >> its start address, because that may make the tree inconsistent, > >> e.g., the resource may no longer be completely contained in its > >> parent, it may conflict with a sibling, etc. > > > > We should not, yes. But... > > > > At the boot time IOV BAR gets as much MMIO space as it can possibly use. > > (Embarassingly I cannot trace where this is coming from, 8GB is selected > > via pci_assign_unassigned_root_bus_resources() path somehow). > > For example, it is 256*32MB=8GB where 256 is maximum PEs number and 32MB > > is a PF/VF BAR size. Whatever shifting we do afterwards, the boudaries of > > that 8GB area do not change and we test it in pnv_pci_vf_resource_shift(): > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/platforms/powernv/pci-ioda.c#n987 > > > >> 2) If we update "res->start", shouldn't we update "res->end" > >> correspondingly? > > > > We have to update the PF's IOV BAR address as we allocate PEs dynamically > > and we do not know in advance where our VF numbers start in that > > 8GB window. So we change IOV BASR start. Changing the end may make it > > look more like there is a free area to use but in reality it won't be > > usable as well as the area we "release" by shifting the start address. > > > > We could probably move that M64 MMIO window by the same delta in > > opposite direction so the IOV BAR start address would remain the same > > but its VF#0 would be mapped to let's say PF#5. I am just afraid there > > is an alignment requirement for these M64 window start address; and this > > would be even more tricky to manage. > > > > We could also create reserved areas for the amount of space "release" by > > moving the start address, not sure how though. > > > > So how do we proceed with this particular patch now? Thanks. > > --- > > drivers/pci/iov.c | 7 ++++--- > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > 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
