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iommu/io-pgtable-arm: Improve attribute handling

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By VMSA rules, using Normal Non-Cacheable type with a shareability
attribute of anything other than Outer Shareable is liable to lead into
unpredictable territory:

| Overlaying the shareability attribute (B3-1377, ARM DDI 0406C.c)
|
| A memory region with a resultant memory type attribute of Normal, and
| a resultant cacheability attribute of Inner Non-cacheable, Outer
| Non-cacheable, must have a resultant shareability attribute of Outer
| Shareable, otherwise shareability is UNPREDICTABLE

Although the SMMU architectures seem to give some slightly stronger
guarantees of Non-Cacheable output types becoming implicitly Outer
Shareable in most cases, we may as well be explicit and not take any
chances. It's also weird that LPAE attribute handling is currently split
between prot_to_pte() and init_pte() given that it can all be statically
determined up-front. Thus, collect *all* the LPAE attributes into
prot_to_pte() in order to logically pick the shareability based on the
incoming IOMMU API prot value, and tweak the short-descriptor code to
stop setting TTBR0.NOS for Non-Cacheable walks.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Robin Murphy 2020-01-10 15:21:51 +00:00 committed by Will Deacon
parent 30d2acb673
commit 7618e47909
2 changed files with 14 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
drivers/iommu/io-pgtable-arm-v7s.c
View file

@ -823,10 +823,9 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
wmb();
/* TTBR */
cfg->arm_v7s_cfg.ttbr = virt_to_phys(data->pgd) |
ARM_V7S_TTBR_S | ARM_V7S_TTBR_NOS |
(cfg->coherent_walk ?
(ARM_V7S_TTBR_IRGN_ATTR(ARM_V7S_RGN_WBWA) |
cfg->arm_v7s_cfg.ttbr = virt_to_phys(data->pgd) | ARM_V7S_TTBR_S |
(cfg->coherent_walk ? (ARM_V7S_TTBR_NOS |
ARM_V7S_TTBR_IRGN_ATTR(ARM_V7S_RGN_WBWA) |
ARM_V7S_TTBR_ORGN_ATTR(ARM_V7S_RGN_WBWA)) :
(ARM_V7S_TTBR_IRGN_ATTR(ARM_V7S_RGN_NC) |
ARM_V7S_TTBR_ORGN_ATTR(ARM_V7S_RGN_NC)));

17
drivers/iommu/io-pgtable-arm.c
View file

@ -293,17 +293,11 @@ static void __arm_lpae_init_pte(struct arm_lpae_io_pgtable *data,
{
arm_lpae_iopte pte = prot;
if (data->iop.cfg.quirks & IO_PGTABLE_QUIRK_ARM_NS)
pte |= ARM_LPAE_PTE_NS;
if (data->iop.fmt != ARM_MALI_LPAE && lvl == ARM_LPAE_MAX_LEVELS - 1)
pte |= ARM_LPAE_PTE_TYPE_PAGE;
else
pte |= ARM_LPAE_PTE_TYPE_BLOCK;
if (data->iop.fmt != ARM_MALI_LPAE)
pte |= ARM_LPAE_PTE_AF;
pte |= ARM_LPAE_PTE_SH_IS;
pte |= paddr_to_iopte(paddr, data);
__arm_lpae_set_pte(ptep, pte, &data->iop.cfg);
@ -460,9 +454,20 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
<< ARM_LPAE_PTE_ATTRINDX_SHIFT);
}
if (prot & IOMMU_CACHE)
pte |= ARM_LPAE_PTE_SH_IS;
else
pte |= ARM_LPAE_PTE_SH_OS;
if (prot & IOMMU_NOEXEC)
pte |= ARM_LPAE_PTE_XN;
if (data->iop.cfg.quirks & IO_PGTABLE_QUIRK_ARM_NS)
pte |= ARM_LPAE_PTE_NS;
if (data->iop.fmt != ARM_MALI_LPAE)
pte |= ARM_LPAE_PTE_AF;
return pte;
}