From 0ac6f4056c4a257f4b230b910e3e6fee6c6fc9b9 Mon Sep 17 00:00:00 2001 From: Yishai Hadas Date: Sun, 1 Feb 2026 16:34:05 +0200 Subject: RDMA/uverbs: Add DMABUF object type and operations MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Expose DMABUF functionality to userspace through the uverbs interface, enabling InfiniBand/RDMA devices to export PCI based memory regions (e.g. device memory) as DMABUF file descriptors. This allows zero-copy sharing of RDMA memory with other subsystems that support the dma-buf framework. A new UVERBS_OBJECT_DMABUF object type and allocation method were introduced. During allocation, uverbs invokes the driver to supply the rdma_user_mmap_entry associated with the given page offset (pgoff). Based on the returned rdma_user_mmap_entry, uverbs requests the driver to provide the corresponding physical-memory details as well as the driver’s PCI provider information. Using this information, dma_buf_export() is called; if it succeeds, uobj->object is set to the underlying file pointer returned by the dma-buf framework. The file descriptor number follows the standard uverbs allocation flow, but the file pointer comes from the dma-buf subsystem, including its own fops and private data. When an mmap entry is removed, uverbs iterates over its associated DMABUFs, marks them as revoked, and calls dma_buf_move_notify() so that their importers are notified. The same procedure applies during the disassociate flow; final cleanup occurs when the application closes the file. Signed-off-by: Yishai Hadas Signed-off-by: Edward Srouji Link: https://patch.msgid.link/20260201-dmabuf-export-v3-2-da238b614fe3@nvidia.com Signed-off-by: Leon Romanovsky --- include/uapi/rdma/ib_user_ioctl_cmds.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'include/uapi/rdma') diff --git a/include/uapi/rdma/ib_user_ioctl_cmds.h b/include/uapi/rdma/ib_user_ioctl_cmds.h index 35da4026f452..72041c1b0ea5 100644 --- a/include/uapi/rdma/ib_user_ioctl_cmds.h +++ b/include/uapi/rdma/ib_user_ioctl_cmds.h @@ -56,6 +56,7 @@ enum uverbs_default_objects { UVERBS_OBJECT_COUNTERS, UVERBS_OBJECT_ASYNC_EVENT, UVERBS_OBJECT_DMAH, + UVERBS_OBJECT_DMABUF, }; enum { @@ -263,6 +264,15 @@ enum uverbs_methods_dmah { UVERBS_METHOD_DMAH_FREE, }; +enum uverbs_attrs_alloc_dmabuf_cmd_attr_ids { + UVERBS_ATTR_ALLOC_DMABUF_HANDLE, + UVERBS_ATTR_ALLOC_DMABUF_PGOFF, +}; + +enum uverbs_methods_dmabuf { + UVERBS_METHOD_DMABUF_ALLOC, +}; + enum uverbs_attrs_reg_dm_mr_cmd_attr_ids { UVERBS_ATTR_REG_DM_MR_HANDLE, UVERBS_ATTR_REG_DM_MR_OFFSET, -- cgit v1.2.3