generic DMA bypass flag

[Christoph Hellwig]

On Fri, Nov 15, 2019 at 06:12:48PM +0000, Robin Murphy wrote:
> And is that any different from where you would choose to "just" set a 
> generic bypass flag?

Same spots, as intel-iommu moves from the identify to a dma domain when
setting a 32-bit mask.  But that means once a 32-bit mask is set we can't
ever go back to the 64-bit one.  And we had a couple drivers playing
interesting games there.  FYI, this is the current intel-iommu
WIP conversion to the dma bypass flag:

http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-bypass