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swiotlb: Add restricted DMA pool initialization

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Add the initialization function to create restricted DMA pools from
matching reserved-memory nodes.

Regardless of swiotlb setting, the restricted DMA pool is preferred if
available.

The restricted DMA pools provide a basic level of protection against the
DMA overwriting buffer contents at unexpected times. However, to protect
against general data leakage and system memory corruption, the system
needs to provide a way to lock down the memory access, e.g., MPU.

Signed-off-by: Claire Chang <tientzu@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Stefano Stabellini <sstabellini@kernel.org>
Tested-by: Will Deacon <will@kernel.org>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Claire Chang
2021-06-19 11:40:41 +08:00
committed by Konrad Rzeszutek Wilk
parent f4111e39a5
commit 0b84e4f8b7
3 changed files with 92 additions and 1 deletions
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14
kernel/dma/Kconfig
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@@ -80,6 +80,20 @@ config SWIOTLB
bool
select NEED_DMA_MAP_STATE
config DMA_RESTRICTED_POOL
bool "DMA Restricted Pool"
depends on OF && OF_RESERVED_MEM
select SWIOTLB
help
This enables support for restricted DMA pools which provide a level of
DMA memory protection on systems with limited hardware protection
capabilities, such as those lacking an IOMMU.
For more information see
<Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt>
and <kernel/dma/swiotlb.c>.
If unsure, say "n".
#
# Should be selected if we can mmap non-coherent mappings to userspace.
# The only thing that is really required is a way to set an uncached bit