IB/core: Encorce MR access rights rules on kernel consumers

Enforce the rule that when requesting remote write or atomic permissions, local
write must be indicated as well. See IB spec 11.2.8.2.

Spotted by: Hagay Abramovsky <hagaya@mellanox.com>
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

include/rdma/ib_verbs.h

@@ -2386,4 +2386,17 @@ struct ib_flow *ib_create_flow(struct ib_qp *qp,
 			       struct ib_flow_attr *flow_attr, int domain);
 int ib_destroy_flow(struct ib_flow *flow_id);
 
+static inline int ib_check_mr_access(int flags)
+{
+	/*
+	 * Local write permission is required if remote write or
+	 * remote atomic permission is also requested.
+	 */
+	if (flags & (IB_ACCESS_REMOTE_ATOMIC | IB_ACCESS_REMOTE_WRITE) &&
+	    !(flags & IB_ACCESS_LOCAL_WRITE))
+		return -EINVAL;
+
+	return 0;
+}
+
 #endif /* IB_VERBS_H */