On Tue, 2016-01-26 at 18:04 -0600, Bjorn Helgaas wrote: > On Tue, Jan 26, 2016 at 04:42:23PM -0700, Alex Williamson wrote: > > On Tue, 2016-01-26 at 17:31 -0600, Bjorn Helgaas wrote: > > > Hi Jacek, > > > > > > When you post updated versions, please post the whole series with a > > > new version number. I think there are three postings of [v2 1/2], and > > > I think they're different. In any case, it's hard for me to keep them > > > straight. > > > > > > On Tue, Jan 26, 2016 at 06:12:15PM +0100, Jacek Lawrynowicz wrote: > > > > This patch solves IOMMU support issues with PCIe non-transparent bridges > > > > that use Requester ID look-up tables (LUT), e.g. PEX8733. Before exiting > > > > the bridge, packet's RID is rewritten according to LUT programmed by > > > > a driver. Modified packets are then passed to a destination bus and > > > > processed upstream. The problem is that such packets seem to come from > > > > non-existent nodes that are hidden behind NTB and are not discoverable > > > > by a destination node, so IOMMU discards them. Adding DMA alias for a > > > > given LUT entry allows IOMMU to create a proper mapping that enables > > > > inter-node communication. > > > > > > > > The current DMA alias implementation supports only single alias, so it's > > > > not possible to connect more than two nodes when IOMMU is enabled. This > > > > implementation enables all possible aliases on a given bus (256) that > > > > are stored in a bitset. Alias devfn is directly translated to a bit > > > > number. The bitset is not allocated for devices that have no need for > > > > DMA aliases. > > > > > > > > More details can be found in following article: > > > > http://www.plxtech.com/files/pdf/technical/expresslane/RTC_Enabling%20MulitHostSystemDesigns > > > > .pdf > > > > > > > > Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@xxxxxxxxx> > > > > Acked-By: David Woodhouse <David.Woodhouse@xxxxxxxxx> > > > > --- > > > > drivers/iommu/iommu.c | 11 ++++------- > > > > drivers/pci/pci.c | 27 +++++++++++++++++++++++++++ > > > > drivers/pci/pci.h | 2 ++ > > > > drivers/pci/probe.c | 1 + > > > > drivers/pci/quirks.c | 15 ++++++--------- > > > > drivers/pci/search.c | 14 +++++++++----- > > > > include/linux/pci.h | 14 +++++++------- > > > > 7 files changed, 56 insertions(+), 28 deletions(-) > > > > > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > > > > index 0e3b009..93a89ed 100644 > > > > --- a/drivers/iommu/iommu.c > > > > +++ b/drivers/iommu/iommu.c > > > > @@ -660,8 +660,8 @@ static struct iommu_group *get_pci_function_alias_group(struct pci_dev > > > > *pdev, > > > > } > > > > > > > > /* > > > > - * Look for aliases to or from the given device for exisiting groups. The > > > > - * dma_alias_devfn only supports aliases on the same bus, therefore the search > > > > + * Look for aliases to or from the given device for exisiting groups. DMA > > > > > > s/exisiting/existing/ (Not your change, but might as well fix the > > > typo since you're touching the line anyway.) > > > > > > > + * aliases are only supported on the same bus, therefore the search > > > > * space is quite small (especially since we're really only looking at pcie > > > > * device, and therefore only expect multiple slots on the root complex or > > > > * downstream switch ports). It's conceivable though that a pair of > > > > @@ -686,11 +686,8 @@ static struct iommu_group *get_pci_alias_group(struct pci_dev *pdev, > > > > continue; > > > > > > > > /* We alias them or they alias us */ > > > > - if (((pdev->dev_flags & PCI_DEV_FLAGS_DMA_ALIAS_DEVFN) && > > > > - pdev->dma_alias_devfn == tmp->devfn) || > > > > - ((tmp->dev_flags & PCI_DEV_FLAGS_DMA_ALIAS_DEVFN) && > > > > - tmp->dma_alias_devfn == pdev->devfn)) { > > > > - > > > > + if (pci_dma_alias_is_enabled(pdev, tmp->devfn) || > > > > + pci_dma_alias_is_enabled(tmp, pdev->devfn)) { > > > > > > I was hoping for something that took two pci_dev pointers and returned > > > true if they were aliases of each other, e.g., > > > > > > bool pci_dma_aliases(struct pci_dev *dev1, struct pci_dev *dev2); > > > > Such a thing could already be created with pci_for_each_dma_alias(). > > Does that mean we could get replace the use of for_each_pci_dev() with some > clever use of pci_for_each_dma_alias()? Not remotely, but if we're going to have an is-alias function, should it be limited to aliases on the same bus? What if I call it on a conventional PCI device where everything on the bus is an alias, this implementation of relying only on the bitmap doesn't even work. Thanks, Alex -- 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
