summaryrefslogtreecommitdiff
path: root/drivers/iommu
diff options
context:
space:
mode:
authorJacek Lawrynowicz <jacek.lawrynowicz@intel.com>2016-03-03 15:38:02 +0100
committerBjorn Helgaas <bhelgaas@google.com>2016-04-11 14:34:32 -0500
commit338c3149a221527e202ee26b1e35f76c965bb6c0 (patch)
treea5dfc811d70258c5abac1422e7bd4484a550c165 /drivers/iommu
parent48c830809ce6e143781172c03a9794cb66802b31 (diff)
PCI: Add support for multiple DMA aliases
Solve IOMMU support issues with PCIe non-transparent bridges that use Requester ID look-up tables (RID-LUT), e.g., the PEX8733. The NTB connects devices in two independent PCI domains. Devices separated by the NTB are not able to discover each other. A PCI packet being forwared from one domain to another has to have its RID modified so it appears on correct bus and completions are forwarded back to the original domain through the NTB. The RID is translated using a preprogrammed table (LUT) and the PCI packet propagates upstream away from the NTB. If the destination system has IOMMU enabled, the packet will be discarded because the new RID is unknown to the IOMMU. Adding a DMA alias for the new RID allows IOMMU to properly recognize the packet. Each device behind the NTB has a unique RID assigned in the RID-LUT. The current DMA alias implementation supports only a single alias, so it's not possible to support mutiple devices behind the NTB when IOMMU is enabled. Enable 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 the following article: http://www.plxtech.com/files/pdf/technical/expresslane/RTC_Enabling%20MulitHostSystemDesigns.pdf Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Alex Williamson <alex.williamson@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Acked-by: Joerg Roedel <jroedel@suse.de>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/iommu.c10
1 files changed, 3 insertions, 7 deletions
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index bfd4f7c3b1d8..1b49e940a318 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 existing groups. DMA
+ * 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 +686,7 @@ 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_devs_are_dma_aliases(pdev, tmp)) {
group = get_pci_alias_group(tmp, devfns);
if (group) {
pci_dev_put(tmp);