Re: [PATCH v2] swiotlb: avoid potential left shift overflow

[Christoph Hellwig]

On Sat, Aug 20, 2022 at 09:42:38AM +0800, Chao Gao wrote:
> In an internal effort to measure the impact of swiotlb size to IO
> performance of confidential VM (e.g., TDX VM), we simply added
> SWIOTLB_ANY to the default io_tlb_mem to lift the restriction on swiotlb
> size. Then we hit this issue and worked out this fix. I posted this
> fix because I think the fix by itself is helpful because it removes the
> implicit dependency of the left-shift in slot_addr() on swiotlb size and
> then someone trying to lift the size limitation won't hit the same issue.

SWIOTLB_ANY is used for real, so I think this is a legitimate fix.
I'll apply it.