On Thu, Jul 02, 2026 at 10:25:16AM +1000, Alexey Kardashevskiy wrote: > > > not externally available so I'll have to trick the DMA layer into > > > using SWIOTLB (which is still all shared, right?) as I specifically > > > want to skip page conversions. Setting low DMA mask won't guarantee > > > that the DMA layer won't allocate a page outside of SWIOTLB and > > > convert it. Manually do > > > > Why so particular? > > aahhh I missed "pre-". I need a way to get pre-shared pages for my > sev-guest activities.
It sounds to me like you don't, what you are worried about is optimizing the dma_alloc_coherent flow to avoid fragmentation and all CC architetures require this optimization. So I'm strongly against you trying to open code something in your driver. Use the DMA API as-is. Propose general DMA API improvements to reduce the fragmentation problem. It is a real problem. Jason
