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When installing a block mapping, we unconditionally overwrite a non-leaf
PTE if we find one. However, this can cause a problem if the following
sequence of events occur:
(1) iommu_map called for a 4k (i.e. PAGE_SIZE) mapping at some address
- We initialise the page table all the way down to a leaf entry
- No TLB maintenance is required, because we're going from invalid
to valid.
(2) iommu_unmap is called on the mapping installed in (1)
- We walk the page table to the final (leaf) entry and zero it
- We only changed a valid leaf entry, so we invalidate leaf-only
(3) iommu_map is called on the same address as (1), but this time for
a 2MB (i.e. BLOCK_SIZE) mapping)
- We walk the page table down to the penultimate level, where we
find a table entry
- We overwrite the table entry with a block mapping and return
without any TLB maintenance and without freeing the memory used
by the now-orphaned table.
This last step can lead to a walk-cache caching the overwritten table
entry, causing unexpected faults when the new mapping is accessed by a
device. One way to fix this would be to collapse the page table when
freeing the last page at a given level, but this would require expensive
iteration on every map call. Instead, this patch detects the case when
we are overwriting a table entry and explicitly unmaps the table first,
which takes care of both freeing and TLB invalidation.
Cc: <stable@vger.kernel.org>
Reported-by: Brian Starkey <brian.starkey@arm.com>
Tested-by: Brian Starkey <brian.starkey@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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| .. | ||
| amd_iommu_init.c | ||
| amd_iommu_proto.h | ||
| amd_iommu_types.h | ||
| amd_iommu_v2.c | ||
| amd_iommu.c | ||
| arm-smmu-v3.c | ||
| arm-smmu.c | ||
| dmar.c | ||
| exynos-iommu.c | ||
| fsl_pamu_domain.c | ||
| fsl_pamu_domain.h | ||
| fsl_pamu.c | ||
| fsl_pamu.h | ||
| intel_irq_remapping.c | ||
| intel-iommu.c | ||
| io-pgtable-arm.c | ||
| io-pgtable.c | ||
| io-pgtable.h | ||
| iommu-sysfs.c | ||
| iommu-traces.c | ||
| iommu.c | ||
| iova.c | ||
| ipmmu-vmsa.c | ||
| irq_remapping.c | ||
| irq_remapping.h | ||
| Kconfig | ||
| Makefile | ||
| msm_iommu_dev.c | ||
| msm_iommu_hw-8xxx.h | ||
| msm_iommu.c | ||
| msm_iommu.h | ||
| of_iommu.c | ||
| omap-iommu-debug.c | ||
| omap-iommu.c | ||
| omap-iommu.h | ||
| omap-iopgtable.h | ||
| rockchip-iommu.c | ||
| shmobile-iommu.c | ||
| shmobile-ipmmu.c | ||
| shmobile-ipmmu.h | ||
| tegra-gart.c | ||
| tegra-smmu.c | ||