RDMA/mlx5: Add support for DMABUF MR registrations with Data-direct

Add support for DMABUF MR registrations with Data-direct device.

Upon userspace calling to register a DMABUF MR with the data direct bit
set, the below algorithm will be followed.

1) Obtain a pinned DMABUF umem from the IB core using the user input
parameters (FD, offset, length) and the DMA PF device.  The DMA PF
device is needed to allow the IOMMU to enable the DMA PF to access the
user buffer over PCI.

2) Create a KSM MKEY by setting its entries according to the user buffer
VA to IOVA mapping, with the MKEY being the data direct device-crossed
MKEY. This KSM MKEY is umrable and will be used as part of the MR cache.
The PD for creating it is the internal device 'data direct' kernel one.

3) Create a crossing MKEY that points to the KSM MKEY using the crossing
access mode.

4) Manage the KSM MKEY by adding it to a list of 'data direct' MKEYs
managed on the mlx5_ib device.

5) Return the crossing MKEY to the user, created with its supplied PD.

Upon DMA PF unbind flow, the driver will revoke the KSM entries.
The final deregistration will occur under the hood once the application
deregisters its MKEY.

Notes:
- This version supports only the PINNED UMEM mode, so there is no
  dependency on ODP.
- The IOVA supplied by the application must be system page aligned due to
  HW translations of KSM.
- The crossing MKEY will not be umrable or part of the MR cache, as we
  cannot change its crossed (i.e. KSM) MKEY over UMR.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://patch.msgid.link/1f99d8020ed540d9702b9e2252a145a439609ba6.1722512548.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>

2 files changed, 8 insertions, 0 deletions

diff --git a/include/uapi/rdma/mlx5_user_ioctl_cmds.h b/include/uapi/rdma/mlx5_user_ioctl_cmds.h
index 5b74d6534899..106276a4cce7 100644
--- a/include/uapi/rdma/mlx5_user_ioctl_cmds.h
+++ b/include/uapi/rdma/mlx5_user_ioctl_cmds.h
@@ -274,6 +274,10 @@ enum mlx5_ib_create_cq_attrs {
 	MLX5_IB_ATTR_CREATE_CQ_UAR_INDEX = UVERBS_ID_DRIVER_NS_WITH_UHW,
 };
 
+enum mlx5_ib_reg_dmabuf_mr_attrs {
+	MLX5_IB_ATTR_REG_DMABUF_MR_ACCESS_FLAGS = (1U << UVERBS_ID_NS_SHIFT),
+};
+
 #define MLX5_IB_DW_MATCH_PARAM 0xA0
 
 struct mlx5_ib_match_params {
diff --git a/include/uapi/rdma/mlx5_user_ioctl_verbs.h b/include/uapi/rdma/mlx5_user_ioctl_verbs.h
index 3189c7f08d17..7c233df475e7 100644
--- a/include/uapi/rdma/mlx5_user_ioctl_verbs.h
+++ b/include/uapi/rdma/mlx5_user_ioctl_verbs.h
@@ -54,6 +54,10 @@ enum mlx5_ib_uapi_flow_action_packet_reformat_type {
 	MLX5_IB_UAPI_FLOW_ACTION_PACKET_REFORMAT_TYPE_L2_TO_L3_TUNNEL = 0x3,
 };
 
+enum mlx5_ib_uapi_reg_dmabuf_flags {
+	MLX5_IB_UAPI_REG_DMABUF_ACCESS_DATA_DIRECT = 1 << 0,
+};
+
 struct mlx5_ib_uapi_devx_async_cmd_hdr {
 	__aligned_u64	wr_id;
 	__u8		out_data[];