On 1/5/21 7:41 PM, Claire Chang wrote:

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 restrict the DMA to a predefined memory
region.

Signed-off-by: Claire Chang <redacted>

You could probably split this patch into two:

- one that introduces the get_io_tlb_mem() getter, updates all callers
of is_swiotlb_buffer() to gain a 'struct device' argument
- another one that does add support for a non-default swiotlb pool and
adds dev->dma_io_tlb_mem

Other than that, LGTM!
-- 
Florian