iommu/arm-smmu: Work around MMU-500 prefetch errata

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MMU-500 erratum #841119 is tickled by a particular set of circumstances
interacting with the next-page prefetcher. Since said prefetcher is
quite dumb and actually detrimental to performance in some cases (by
causing unwanted TLB evictions for non-sequential access patterns), we
lose very little by turning it off, and what we gain is a guarantee that
the erratum is never hit.

As a bonus, the same workaround will also prevent erratum #826419 once
v7 short descriptor support is implemented.

CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Will Deacon <will.deacon@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

...

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Robin Murphy 2016-04-13 18:12:59 +01:00 • committed by Will Deacon

parent e086d912d4

commit f0cfffc48c

2 changed files with 16 additions and 1 deletions

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1

Documentation/arm64/silicon-errata.txt

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16

drivers/iommu/arm-smmu.c

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