iommu/io-pgtable-arm-v7s: Support lockless operation
Mirroring the LPAE implementation, rework the v7s code to be robust against concurrent operations. The same two potential races exist, and are solved in the same manner, with the fixed 2-level structure making life ever so slightly simpler. What complicates matters compared to LPAE, however, is large page entries, since we can't update a block of 16 PTEs atomically, nor assume available software bits to do clever things with. As most users are never likely to do partial unmaps anyway (due to DMA API rules), it doesn't seem unreasonable for this case to remain behind a serialising lock; we just pull said lock down into the bowels of the implementation so it's well out of the way of the normal call paths. Signed-off-by:Robin Murphy <robin.murphy@arm.com> Signed-off-by:
Will Deacon <will.deacon@arm.com>
parent
2c3d273e
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