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H A Dntb_transport.cdiff c59666bb32b91da84b1d3df0e88789de9e827f61 Fri Jan 18 18:10:01 CST 2019 Logan Gunthorpe <logang@deltatee.com> NTB: ntb_transport: Ensure the destination buffer is mapped for TX DMA

Presently, when ntb_transport is used with DMA and the IOMMU turned on,
it fails with errors from the IOMMU such as:

DMAR: DRHD: handling fault status reg 202
DMAR: [DMA Write] Request device [00:04.0] fault addr
381fc0340000 [fault reason 05] PTE Write access is not set

This is because ntb_transport does not map the BAR space with the IOMMU.

To fix this, we map the entire MW region for each QP after we assign
the DMA channel. This prevents needing an extra DMA map in the fast
path.

Link: https://lore.kernel.org/linux-pci/499934e7-3734-1aee-37dd-b42a5d2a2608@intel.com/
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>