Hi Claire,
On Thu, Jun 24, 2021 at 11:55:24PM +0800, Claire Chang wrote:
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
include/linux/swiotlb.h | 3 +- kernel/dma/Kconfig | 14 ++++++++ kernel/dma/swiotlb.c | 76 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 92 insertions(+), 1 deletion(-)
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 3b9454d1e498..39284ff2a6cd 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -73,7 +73,8 @@ extern enum swiotlb_force swiotlb_force;
range check to see if the memory was in fact allocated by thisAPI.- @nslabs: The number of IO TLB blocks (in groups of 64) between @start and
@end. This is command line adjustable via setup_io_tlb_npages.
@end. For default swiotlb, this is command line adjustable via
setup_io_tlb_npages.- @used: The number of used IO TLB block.
- @list: The free list describing the number of free entries available
from each index.diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig index 77b405508743..3e961dc39634 100644 --- a/kernel/dma/Kconfig +++ b/kernel/dma/Kconfig @@ -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
This makes SWIOTLB user configurable, which in turn results in
mips64-linux-ld: arch/mips/kernel/setup.o: in function `arch_mem_init': setup.c:(.init.text+0x19c8): undefined reference to `plat_swiotlb_setup' make[1]: *** [Makefile:1280: vmlinux] Error 1
when building mips:allmodconfig.
Should this possibly be "depends on SWIOTLB" ?
Thanks, Guenter