iommu/vt-d: Implement SVM_FLAG_SUPERVISOR_MODE for kernel access

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This is only usable for the static 1:1 mapping of physical memory.

Any access to vmalloc or module regions will require some way of doing
an IOTLB flush. It's theoretically possible to hook into the
tlb_flush_kernel_range() function, but that seems like overkill — most
of the addresses accessed through a kernel PASID *will* be in the 1:1
mapping.

If we really need to allow access to more interesting kernel regions,
then the answer will probably be an explicit IOTLB flush call after use,
akin to the DMA API's unmap function.

In fact, it might be worth introducing that sooner rather than later, and
making it just BUG() if the address isn't in the static 1:1 mapping.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

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This commit is contained in:

David Woodhouse 2015-10-15 15:52:15 +01:00

parent 569e4f7782

commit 5cec753709

2 changed files with 45 additions and 13 deletions

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43

drivers/iommu/intel-svm.c

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15

include/linux/intel-svm.h

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