Messages in this thread | | | From | FUJITA Tomonori <> | Subject | [PATCH v2 -mm 0/2] x86: per-device dma_mapping_ops | Date | Mon, 19 May 2008 15:31:27 +0900 |
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This is an updated version of the patchset to add per-device dma_mapping_ops support for CONFIG_X86_64 like POWER architecture does:
http://lkml.org/lkml/2008/5/13/36
This is against 2.6.26-rc2-mm1 (the changes since the v1 are pretty trivial like dropping the change for v850 arch).
This enables us to cleanly fix the Calgary IOMMU issue that some devices are not behind the IOMMU [1].
I think that per-device dma_mapping_ops support would be also helpful for KVM people to support PCI passthrough but Andi thinks that this makes it difficult to support the PCI passthrough (see the above thread). So I CC'ed this to KVM camp. Comments are appreciated.
A pointer to dma_mapping_ops to struct dev_archdata is added. If the pointer is non NULL, DMA operations in asm/dma-mapping.h use it. If it's NULL, the system-wide dma_ops pointer is used as before.
If it's useful for KVM people, I plan to implement a mechanism to register a hook called when a new pci (or dma capable) device is created (it works with hot plugging). It enables IOMMUs to set up an appropriate dma_mapping_ops per device.
The major obstacle is that dma_mapping_error doesn't take a pointer to the device unlike other DMA operations. So x86 can't have dma_mapping_ops per device. Note all the POWER IOMMUs use the same dma_mapping_error function so this is not a problem for POWER but x86 IOMMUs use different dma_mapping_error functions.
The first patch adds the device argument to dma_mapping_error. The patch is trivial but large since it touches lots of drivers and dma-mapping.h in all the architecture.
[1] http://lkml.org/lkml/2008/5/8/423
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