On 25.03.2026 20:23, Jiri Pirko wrote: > From: Jiri Pirko <[email protected]> > > Confidential computing (CoCo) VMs/guests, such as AMD SEV and Intel TDX, > run with private/encrypted memory which creates a challenge > for devices that do not support DMA to it (no TDISP support). > > For kernel-only DMA operations, swiotlb bounce buffering provides a > transparent solution by copying data through shared memory. > However, the only way to get this memory into userspace is via the DMA > API's dma_alloc_pages()/dma_mmap_pages() type interfaces which limits > the use of the memory to a single DMA device, and is incompatible with > pin_user_pages(). > > These limitations are particularly problematic for the RDMA subsystem > which makes heavy use of pin_user_pages() and expects flexible memory > usage between many different DMA devices. > > This patch series enables userspace to explicitly request shared > (decrypted) memory allocations from new dma-buf system_cc_shared heap. > Userspace can mmap this memory and pass the dma-buf fd to other > existing importers such as RDMA or DRM devices to access the > memory. The DMA API is improved to allow the dma heap exporter to DMA > map the shared memory to each importing device. > > Based on dma-mapping-for-next e7442a68cd1ee797b585f045d348781e9c0dde0d
I would like to merge this to dma-mapping-next, but I feel a bit uncomfortable with my lack of knowledge about CoCo and friends. Could those who know a bit more about it provide some Reviewed-by tags? Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
