[PATCH rdma-next v3 3/3] RDMA/mlx5: Use UMEM attribute for SRQ doorbell record

[Jiri Pirko <jiri@resnulli.us>]

From: Jiri Pirko <jiri@nvidia.com>

Add an optional mlx5 driver-namespace UMEM attribute on SRQ create so
userspace can supply the doorbell record umem explicitly, symmetric to
the CQ and QP sides. Resolve it inside mlx5_ib_db_map_user() and use it
as a private DBR page when present; otherwise take the existing UHW
share-or-pin path that preserves per-page DBR sharing across CQ/QP/SRQ
in the same process.

Add mlx5's first UVERBS_OBJECT_SRQ UAPI definition chain to attach the
new attr.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
 drivers/infiniband/hw/mlx5/main.c        |  1 +
 drivers/infiniband/hw/mlx5/mlx5_ib.h     |  1 +
 drivers/infiniband/hw/mlx5/srq.c         | 19 ++++++++++++++++++-
 include/uapi/rdma/mlx5_user_ioctl_cmds.h |  4 ++++
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index 02809114fc79..bdf59537f87b 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -4477,6 +4477,7 @@ static const struct uapi_definition mlx5_ib_defs[] = {
 	UAPI_DEF_CHAIN(mlx5_ib_dm_defs),
 	UAPI_DEF_CHAIN(mlx5_ib_create_cq_defs),
 	UAPI_DEF_CHAIN(mlx5_ib_create_qp_defs),
+	UAPI_DEF_CHAIN(mlx5_ib_create_srq_defs),
 
 	UAPI_DEF_CHAIN_OBJ_TREE(UVERBS_OBJECT_DEVICE, &mlx5_ib_query_context),
 	UAPI_DEF_CHAIN_OBJ_TREE(UVERBS_OBJECT_MR, &mlx5_ib_reg_dmabuf_mr),
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 522984d958bb..e9ddf2e97a76 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -1517,6 +1517,7 @@ extern const struct uapi_definition mlx5_ib_qos_defs[];
 extern const struct uapi_definition mlx5_ib_std_types_defs[];
 extern const struct uapi_definition mlx5_ib_create_cq_defs[];
 extern const struct uapi_definition mlx5_ib_create_qp_defs[];
+extern const struct uapi_definition mlx5_ib_create_srq_defs[];
 
 static inline int is_qp1(enum ib_qp_type qp_type)
 {
diff --git a/drivers/infiniband/hw/mlx5/srq.c b/drivers/infiniband/hw/mlx5/srq.c
index 6fa4c5a9a0d5..a973c1b7515f 100644
--- a/drivers/infiniband/hw/mlx5/srq.c
+++ b/drivers/infiniband/hw/mlx5/srq.c
@@ -10,6 +10,9 @@
 #include "mlx5_ib.h"
 #include "srq.h"
 
+#define UVERBS_MODULE_NAME mlx5_ib
+#include <rdma/uverbs_named_ioctl.h>
+
 static void *get_wqe(struct mlx5_ib_srq *srq, int n)
 {
 	return mlx5_frag_buf_get_wqe(&srq->fbc, n);
@@ -78,7 +81,9 @@ static int create_srq_user(struct ib_pd *pd, struct mlx5_ib_srq *srq,
 	}
 	in->umem = srq->umem;
 
-	err = mlx5_ib_db_map_user(ucontext, NULL, 0, ucmd.db_addr, &srq->db);
+	err = mlx5_ib_db_map_user(ucontext, attrs,
+				  MLX5_IB_ATTR_CREATE_SRQ_DBR_BUF_UMEM,
+				  ucmd.db_addr, &srq->db);
 	if (err) {
 		mlx5_ib_dbg(dev, "map doorbell failed\n");
 		goto err_umem;
@@ -466,3 +471,15 @@ int mlx5_ib_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
 
 	return err;
 }
+
+ADD_UVERBS_ATTRIBUTES_SIMPLE(
+	mlx5_ib_srq_create,
+	UVERBS_OBJECT_SRQ,
+	UVERBS_METHOD_SRQ_CREATE,
+	UVERBS_ATTR_UMEM(MLX5_IB_ATTR_CREATE_SRQ_DBR_BUF_UMEM,
+			 UA_OPTIONAL));
+
+const struct uapi_definition mlx5_ib_create_srq_defs[] = {
+	UAPI_DEF_CHAIN_OBJ_TREE(UVERBS_OBJECT_SRQ, &mlx5_ib_srq_create),
+	{},
+};
diff --git a/include/uapi/rdma/mlx5_user_ioctl_cmds.h b/include/uapi/rdma/mlx5_user_ioctl_cmds.h
index ddb898afd813..3528743e3858 100644
--- a/include/uapi/rdma/mlx5_user_ioctl_cmds.h
+++ b/include/uapi/rdma/mlx5_user_ioctl_cmds.h
@@ -281,6 +281,10 @@ enum mlx5_ib_create_qp_attrs {
 	MLX5_IB_ATTR_CREATE_QP_DBR_BUF_UMEM = UVERBS_ID_DRIVER_NS_WITH_UHW,
 };
 
+enum mlx5_ib_create_srq_attrs {
+	MLX5_IB_ATTR_CREATE_SRQ_DBR_BUF_UMEM = 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),
 };
-- 
2.54.0