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@xxxxxxxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Tested-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> > Tested-by: Will Deacon <will@xxxxxxxxxx> > --- > 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 this > * API. > * @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
