Hey all,
This is a followup to my previous RFC [1], which now makes use of the dynamic attachment API implemented in the RDMA subsystem, but calls dma_buf_pin() in order to make sure that the move_notify callback will not be used, as suggested by Christian. As explained in the previous RFC, move_notify requires the RDMA device to support on-demand-paging (ODP) which is not common on most devices (only supported by mlx5).
While the dynamic requirement makes sense for certain GPUs, some devices (such as habanalabs) have device memory that is always "pinned" and do not need/use the move_notify operation.
The first patch changes the dmabuf documentation to make it clear that pinning does not necessarily mean the memory must be moved to system memory, it is up to the exporter to decide.
The motivation of this RFC is to use habanalabs as the dmabuf exporter, and EFA as the importer to allow for peer2peer access through libibverbs.
[1] https://lore.kernel.org/linux-rdma/20210818074352.29950-1-galpress@amazon.co...
Thanks
Gal Pressman (2): dma-buf: Fix pin callback comment RDMA/efa: Add support for dmabuf memory regions
drivers/infiniband/hw/efa/efa.h | 4 + drivers/infiniband/hw/efa/efa_main.c | 1 + drivers/infiniband/hw/efa/efa_verbs.c | 166 +++++++++++++++++++++----- include/linux/dma-buf.h | 4 +- 4 files changed, 142 insertions(+), 33 deletions(-)