Commit ffff8858 authored Apr 13, 2017 by Jayachandran C Committed by Bjorn Helgaas Apr 13, 2017

PCI: Add device flag PCI_DEV_FLAGS_BRIDGE_XLATE_ROOT

Add a new quirk flag PCI_DEV_FLAGS_BRIDGE_XLATE_ROOT to limit the DMA alias
search to go no further than the bridge where the IOMMU unit is attached.

The flag will be used to indicate a bridge device which forwards the
address translation requests to the IOMMU, i.e., where the interrupt and
DMA requests leave the PCIe hierarchy and go into the system blocks.

Usually this happens at the PCI RC, so this flag is not needed.  But on
systems where there are bridges that introduce aliases above the IOMMU,
this flag prevents pci_for_each_dma_alias() from generating aliases that
the IOMMU will never see.

The function pci_for_each_dma_alias() is updated to stop when it see a
bridge with this flag set.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=195447


Signed-off-by: Jayachandran C <jnair@caviumnetworks.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: David Daney <david.daney@cavium.com>

parent b77d537d

drivers/pci/search.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -60,6 +60,10 @@ int pci_for_each_dma_alias(struct pci_dev *pdev,

		tmp = bus->self;

		/* stop at bridge where translation unit is associated */
		if (tmp->dev_flags & PCI_DEV_FLAGS_BRIDGE_XLATE_ROOT)
		return ret;

		/*
		* PCIe-to-PCI/X bridges alias transactions from downstream
		* devices using the subordinate bus number (PCI Express to

include/linux/pci.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -178,6 +178,8 @@ enum pci_dev_flags {
		PCI_DEV_FLAGS_NO_PM_RESET = (__force pci_dev_flags_t) (1 << 7),
		/* Get VPD from function 0 VPD */
		PCI_DEV_FLAGS_VPD_REF_F0 = (__force pci_dev_flags_t) (1 << 8),
		/* a non-root bridge where translation occurs, stop alias search here */
		PCI_DEV_FLAGS_BRIDGE_XLATE_ROOT = (__force pci_dev_flags_t) (1 << 9),
		};

		enum pci_irq_reroute_variant {

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