verbs: Introduce ibv_import/unimport_mr() verbs

Introduce ibv_import/unimport_mr() verbs, this enables an application which previously imported the device and an associated PD to import an MR that is associated with. A detailed man page as part of this patch describes the expected usage and flow. Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
linux-rdma · Jul 9, 2020 · 4fdaac9 · 4fdaac9
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diff --git a/debian/libibverbs1.symbols b/debian/libibverbs1.symbols
@@ -68,6 +68,7 @@ libibverbs.so.1 libibverbs1 #MINVER#
  ibv_get_pkey_index@IBVERBS_1.5 20
  ibv_get_sysfs_path@IBVERBS_1.0 1.1.6
  ibv_import_device@IBVERBS_1.10 31
+ ibv_import_mr@IBVERBS_1.10 31
  ibv_import_pd@IBVERBS_1.10 31
  ibv_init_ah_from_wc@IBVERBS_1.1 1.1.6
  ibv_modify_qp@IBVERBS_1.0 1.1.6
@@ -105,6 +106,7 @@ libibverbs.so.1 libibverbs1 #MINVER#
  ibv_resize_cq@IBVERBS_1.1 1.1.6
  ibv_resolve_eth_l2_from_gid@IBVERBS_1.1 1.2.0
  ibv_set_ece@IBVERBS_1.10 31
+ ibv_unimport_mr@IBVERBS_1.10 31
  ibv_unimport_pd@IBVERBS_1.10 31
  ibv_wc_status_str@IBVERBS_1.1 1.1.6
  mbps_to_ibv_rate@IBVERBS_1.1 1.1.8

diff --git a/libibverbs/driver.h b/libibverbs/driver.h
@@ -318,6 +318,8 @@ struct verbs_context_ops {
 	void (*free_context)(struct ibv_context *context);
 	int (*free_dm)(struct ibv_dm *dm);
 	int (*get_srq_num)(struct ibv_srq *srq, uint32_t *srq_num);
+	struct ibv_mr *(*import_mr)(struct ibv_pd *pd,
+				    uint32_t mr_handle);
 	struct ibv_pd *(*import_pd)(struct ibv_context *context,
 				    uint32_t pd_handle);
 	int (*modify_cq)(struct ibv_cq *cq, struct ibv_modify_cq_attr *attr);
@@ -372,6 +374,7 @@ struct verbs_context_ops {
 			void *addr, size_t length, int access);
 	int (*resize_cq)(struct ibv_cq *cq, int cqe);
 	int (*set_ece)(struct ibv_qp *qp, struct ibv_ece *ece);
+	void (*unimport_mr)(struct ibv_mr *mr);
 	void (*unimport_pd)(struct ibv_pd *pd);
 };
 

diff --git a/libibverbs/dummy_ops.c b/libibverbs/dummy_ops.c
@@ -287,6 +287,13 @@ static int get_srq_num(struct ibv_srq *srq, uint32_t *srq_num)
 	return EOPNOTSUPP;
 }
 
+static struct ibv_mr *import_mr(struct ibv_pd *pd,
+				uint32_t mr_handle)
+{
+	errno = EOPNOTSUPP;
+	return NULL;
+}
+
 static struct ibv_pd *import_pd(struct ibv_context *context,
 				uint32_t pd_handle)
 {
@@ -467,6 +474,10 @@ static int set_ece(struct ibv_qp *qp, struct ibv_ece *ece)
 	return EOPNOTSUPP;
 }
 
+static void unimport_mr(struct ibv_mr *mr)
+{
+}
+
 static void unimport_pd(struct ibv_pd *pd)
 {
 }
@@ -525,6 +536,7 @@ const struct verbs_context_ops verbs_dummy_ops = {
 	free_context,
 	free_dm,
 	get_srq_num,
+	import_mr,
 	import_pd,
 	modify_cq,
 	modify_flow_action_esp,
@@ -553,6 +565,7 @@ const struct verbs_context_ops verbs_dummy_ops = {
 	rereg_mr,
 	resize_cq,
 	set_ece,
+	unimport_mr,
 	unimport_pd,
 };
 
@@ -645,6 +658,7 @@ void verbs_set_ops(struct verbs_context *vctx,
 	SET_PRIV_OP_IC(ctx, free_context);
 	SET_OP(vctx, free_dm);
 	SET_OP(vctx, get_srq_num);
+	SET_PRIV_OP_IC(vctx, import_mr);
 	SET_PRIV_OP_IC(vctx, import_pd);
 	SET_OP(vctx, modify_cq);
 	SET_OP(vctx, modify_flow_action_esp);
@@ -673,6 +687,7 @@ void verbs_set_ops(struct verbs_context *vctx,
 	SET_PRIV_OP(ctx, rereg_mr);
 	SET_PRIV_OP(ctx, resize_cq);
 	SET_PRIV_OP_IC(vctx, set_ece);
+	SET_PRIV_OP_IC(vctx, unimport_mr);
 	SET_PRIV_OP_IC(vctx, unimport_pd);
 
 #undef SET_OP

diff --git a/libibverbs/libibverbs.map.in b/libibverbs/libibverbs.map.in
@@ -134,9 +134,11 @@ IBVERBS_1.9 {
 IBVERBS_1.10 {
 	global:
 		ibv_import_device;
+		ibv_import_mr;
 		ibv_import_pd;
 		ibv_query_ece;
 		ibv_set_ece;
+		ibv_unimport_mr;
 		ibv_unimport_pd;
 } IBVERBS_1.9;
 

diff --git a/libibverbs/man/CMakeLists.txt b/libibverbs/man/CMakeLists.txt
@@ -38,6 +38,7 @@ rdma_man_pages(
   ibv_get_pkey_index.3.md
   ibv_get_srq_num.3.md
   ibv_import_device.3.md
+  ibv_import_mr.3.md
   ibv_import_pd.3.md
   ibv_inc_rkey.3.md
   ibv_modify_qp.3
@@ -103,6 +104,7 @@ rdma_alias_man_pages(
   ibv_get_cq_event.3 ibv_ack_cq_events.3
   ibv_get_device_list.3 ibv_free_device_list.3
   ibv_import_pd.3 ibv_unimport_pd.3
+  ibv_import_mr.3 ibv_unimport_mr.3
   ibv_open_device.3 ibv_close_device.3
   ibv_open_xrcd.3 ibv_close_xrcd.3
   ibv_rate_to_mbps.3 mbps_to_ibv_rate.3

diff --git a/libibverbs/man/ibv_import_mr.3.md b/libibverbs/man/ibv_import_mr.3.md
@@ -0,0 +1,64 @@
+---
+date: 2020-5-3
+footer: libibverbs
+header: "Libibverbs Programmer's Manual"
+layout: page
+license: 'Licensed under the OpenIB.org BSD license (FreeBSD Variant) - See COPYING.md'
+section: 3
+title: ibv_import_mr ibv_unimport_mr
+---
+
+# NAME
+
+ibv_import_mr - import an MR from a given ibv_pd
+
+ibv_unimport_mr - unimport an MR
+
+# SYNOPSIS
+
+```c
+#include <infiniband/verbs.h>
+
+struct ibv_mr *ibv_import_mr(struct ibv_pd *pd, uint32_t mr_handle);
+void ibv_unimport_mr(struct ibv_mr *mr)
+
+```
+
+
+# DESCRIPTION
+
+**ibv_import_mr()** returns a Memory region (MR) that is associated with the given
+*mr_handle* in the RDMA context that assosicated with the given *pd*.
+
+The input *mr_handle* value must be a valid kernel handle for an MR object in the assosicated RDMA context.
+It can be achieved from the original MR by getting its ibv_mr->handle member value.
+
+**ibv_unimport_mr()** un import the MR.
+Once the MR usage has been ended ibv_dereg_mr() or ibv_unimport_mr() should be called.
+The first one will go to the kernel to destroy the object once the second one way cleanup what
+ever is needed/opposite of the import without calling the kernel.
+
+This is the responsibility of the application to coordinate between all ibv_context(s) that use this MR.
+Once destroy is done no other process can touch the object except for unimport. All users of the context must
+collaborate to ensure this.
+
+# RETURN VALUE
+
+**ibv_import_mr()** returns a pointer to the allocated MR, or NULL if the request fails.
+
+# NOTES
+
+The *addr* field in the imported MR is not applicable, NULL value is expected.
+
+# SEE ALSO
+
+**ibv_reg_mr**(3),
+**ibv_reg_dm_mr**(3),
+**ibv_reg_mr_iova**(3),
+**ibv_reg_mr_iova2**(3),
+**ibv_dereg_mr**(3),
+
+# AUTHOR
+
+Yishai Hadas <yishaih@mellanox.com>
+
diff --git a/libibverbs/verbs.c b/libibverbs/verbs.c
@@ -366,6 +366,22 @@ void ibv_unimport_pd(struct ibv_pd *pd)
 }
 
 
+/**
+ * ibv_import_mr - Import a memory region
+ */
+struct ibv_mr *ibv_import_mr(struct ibv_pd *pd, uint32_t mr_handle)
+{
+	return get_ops(pd->context)->import_mr(pd, mr_handle);
+}
+
+/**
+ * ibv_unimport_mr - Unimport a memory region
+ */
+void ibv_unimport_mr(struct ibv_mr *mr)
+{
+	get_ops(mr->context)->unimport_mr(mr);
+}
+
 LATEST_SYMVER_FUNC(ibv_rereg_mr, 1_1, "IBVERBS_1.1",
 		   int,
 		   struct ibv_mr *mr, int flags,

diff --git a/libibverbs/verbs.h b/libibverbs/verbs.h
@@ -2257,6 +2257,16 @@ struct ibv_pd *ibv_import_pd(struct ibv_context *context,
  */
 void ibv_unimport_pd(struct ibv_pd *pd);
 
+/**
+ * ibv_import_mr - Import a memory region
+ */
+struct ibv_mr *ibv_import_mr(struct ibv_pd *pd, uint32_t mr_handle);
+
+/**
+ * ibv_unimport_mr - Unimport a memory region
+ */
+void ibv_unimport_mr(struct ibv_mr *mr);
+
 /**
  * ibv_get_async_event - Get next async event
  * @event: Pointer to use to return async event