On Wed, 23 Jul 2025 16:00:01 +0300 Leon Romanovsky <leon@xxxxxxxxxx> wrote: > From: Leon Romanovsky <leonro@xxxxxxxxxx> > > --------------------------------------------------------------------------- > Based on blk and DMA patches which will be sent during coming merge window. > --------------------------------------------------------------------------- > > This series extends the VFIO PCI subsystem to support exporting MMIO regions > from PCI device BARs as dma-buf objects, enabling safe sharing of non-struct > page memory with controlled lifetime management. This allows RDMA and other > subsystems to import dma-buf FDs and build them into memory regions for PCI > P2P operations. > > The series supports a use case for SPDK where a NVMe device will be owned > by SPDK through VFIO but interacting with a RDMA device. The RDMA device > may directly access the NVMe CMB or directly manipulate the NVMe device's > doorbell using PCI P2P. > > However, as a general mechanism, it can support many other scenarios with > VFIO. This dmabuf approach can be usable by iommufd as well for generic > and safe P2P mappings. I think this will eventually enable DMA mapping of device MMIO through an IOMMUFD IOAS for the VM P2P use cases, right? How do we get from what appears to be a point-to-point mapping between two devices to a shared IOVA between multiple devices? I'm guessing we need IOMMUFD to support something like IOMMU_IOAS_MAP_FILE for dma-buf, but I can't connect all the dots. Thanks, Alex
