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iommu/io-pgtable-arm: Rationalise TTBRn handling

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TTBR1 values have so far been redundant since no users implement any
support for split address spaces. Crucially, though, one of the main
reasons for wanting to do so is to be able to manage each half entirely
independently, e.g. context-switching one set of mappings without
disturbing the other. Thus it seems unlikely that tying two tables
together in a single io_pgtable_cfg would ever be particularly desirable
or useful.

Streamline the configs to just a single conceptual TTBR value
representing the allocated table. This paves the way for future users to
support split address spaces by simply allocating a table and dealing
with the detailed TTBRn logistics themselves.

Tested-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[will: Drop change to ttbr value]
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Robin Murphy 2019-10-25 19:08:37 +01:00 • committed by Will Deacon
parent cd037ff2f9
commit d1e5f26f14
9 changed files with 23 additions and 27 deletions
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4
include/linux/io-pgtable.h
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@ -100,7 +100,7 @@ struct io_pgtable_cfg {
/* Low-level data specific to the table format */
union {
struct {
u64 ttbr[2];
u64 ttbr;
u64 tcr;
u64 mair;
} arm_lpae_s1_cfg;
@ -111,7 +111,7 @@ struct io_pgtable_cfg {
} arm_lpae_s2_cfg;
struct {
u32 ttbr[2];
u32 ttbr;
u32 tcr;
u32 nmrr;
u32 prrr;