gpxe/src/net/infiniband/ib_cm.c - platform/external/syslinux - Git at Google

 /*
  * Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
  * published by the Free Software Foundation; either version 2 of the
  * License, or any later version.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */

 FILE_LICENCE ( GPL2_OR_LATER );

 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <byteswap.h>
 #include <errno.h>
 #include <assert.h>
 #include <gpxe/infiniband.h>
 #include <gpxe/ib_mi.h>
 #include <gpxe/ib_pathrec.h>
 #include <gpxe/ib_cm.h>

 /**
  * @file
  *
  * Infiniband communication management
  *
  */

 /** List of connections */
 static LIST_HEAD ( ib_cm_conns );

 /**
  * Send "ready to use" response
  *
  * @v ibdev		Infiniband device
  * @v mi		Management interface
  * @v conn		Connection
  * @v av		Address vector
  * @ret rc		Return status code
  */
 static int ib_cm_send_rtu ( struct ib_device *ibdev,
 			    struct ib_mad_interface *mi,
 			    struct ib_connection *conn,
 			    struct ib_address_vector *av ) {
 	union ib_mad mad;
 	struct ib_cm_ready_to_use *ready =
 		&mad.cm.cm_data.ready_to_use;
 	int rc;

 	/* Construct "ready to use" response */
 	memset ( &mad, 0, sizeof ( mad ) );
 	mad.hdr.mgmt_class = IB_MGMT_CLASS_CM;
 	mad.hdr.class_version = IB_CM_CLASS_VERSION;
 	mad.hdr.method = IB_MGMT_METHOD_SEND;
 	mad.hdr.attr_id = htons ( IB_CM_ATTR_READY_TO_USE );
 	ready->local_id = htonl ( conn->local_id );
 	ready->remote_id = htonl ( conn->remote_id );
 	if ( ( rc = ib_mi_send ( ibdev, mi, &mad, av ) ) != 0 ){
 		DBGC ( conn, "CM %p could not send RTU: %s\n",
 		       conn, strerror ( rc ) );
 		return rc;
 	}

 	return 0;
 }

 /**
  * Handle duplicate connection replies
  *
  * @v ibdev		Infiniband device
  * @v mi		Management interface
  * @v mad		Received MAD
  * @v av		Source address vector
  * @ret rc		Return status code
  *
  * If a "ready to use" MAD is lost, the peer may resend the connection
  * reply.  We have to respond to these with duplicate "ready to use"
  * MADs, otherwise the peer may time out and drop the connection.
  */
 static void ib_cm_connect_rep ( struct ib_device *ibdev,
 				struct ib_mad_interface *mi,
 				union ib_mad *mad,
 				struct ib_address_vector *av ) {
 	struct ib_cm_connect_reply *connect_rep =
 		&mad->cm.cm_data.connect_reply;
 	struct ib_connection *conn;
 	int rc;

 	/* Identify connection */
 	list_for_each_entry ( conn, &ib_cm_conns, list ) {
 		if ( ntohl ( connect_rep->remote_id ) != conn->local_id )
 			continue;
 		/* Try to send "ready to use" reply */
 		if ( ( rc = ib_cm_send_rtu ( ibdev, mi, conn, av ) ) != 0 ) {
 			/* Ignore errors */
 			return;
 		}
 		return;
 	}

 	DBG ( "CM unidentified connection %08x\n",
 	      ntohl ( connect_rep->remote_id ) );
 }

 /** Communication management agents */
 struct ib_mad_agent ib_cm_agent[] __ib_mad_agent = {
 	{
 		.mgmt_class = IB_MGMT_CLASS_CM,
 		.class_version = IB_CM_CLASS_VERSION,
 		.attr_id = htons ( IB_CM_ATTR_CONNECT_REPLY ),
 		.handle = ib_cm_connect_rep,
 	},
 };

 /**
  * Convert connection rejection reason to return status code
  *
  * @v reason		Rejection reason (in network byte order)
  * @ret rc		Return status code
  */
 static int ib_cm_rejection_reason_to_rc ( uint16_t reason ) {
 	switch ( reason ) {
 	case htons ( IB_CM_REJECT_BAD_SERVICE_ID ) :
 		return -ENODEV;
 	case htons ( IB_CM_REJECT_STALE_CONN ) :
 		return -EALREADY;
 	case htons ( IB_CM_REJECT_CONSUMER ) :
 		return -ENOTTY;
 	default:
 		return -EPERM;
 	}
 }

 /**
  * Handle connection request transaction completion
  *
  * @v ibdev		Infiniband device
  * @v mi		Management interface
  * @v madx		Management transaction
  * @v rc		Status code
  * @v mad		Received MAD (or NULL on error)
  * @v av		Source address vector (or NULL on error)
  */
 static void ib_cm_req_complete ( struct ib_device *ibdev,
 				 struct ib_mad_interface *mi,
 				 struct ib_mad_transaction *madx,
 				 int rc, union ib_mad *mad,
 				 struct ib_address_vector *av ) {
 	struct ib_connection *conn = ib_madx_get_ownerdata ( madx );
 	struct ib_queue_pair *qp = conn->qp;
 	struct ib_cm_common *common = &mad->cm.cm_data.common;
 	struct ib_cm_connect_reply *connect_rep =
 		&mad->cm.cm_data.connect_reply;
 	struct ib_cm_connect_reject *connect_rej =
 		&mad->cm.cm_data.connect_reject;
 	void *private_data = NULL;
 	size_t private_data_len = 0;

 	/* Report failures */
 	if ( ( rc == 0 ) && ( mad->hdr.status != htons ( IB_MGMT_STATUS_OK ) ))
 		rc = -EIO;
 	if ( rc != 0 ) {
 		DBGC ( conn, "CM %p connection request failed: %s\n",
 		       conn, strerror ( rc ) );
 		goto out;
 	}

 	/* Record remote communication ID */
 	conn->remote_id = ntohl ( common->local_id );

 	/* Handle response */
 	switch ( mad->hdr.attr_id ) {

 	case htons ( IB_CM_ATTR_CONNECT_REPLY ) :
 		/* Extract fields */
 		qp->av.qpn = ( ntohl ( connect_rep->local_qpn ) >> 8 );
 		qp->send.psn = ( ntohl ( connect_rep->starting_psn ) >> 8 );
 		private_data = &connect_rep->private_data;
 		private_data_len = sizeof ( connect_rep->private_data );
 		DBGC ( conn, "CM %p connected to QPN %lx PSN %x\n",
 		       conn, qp->av.qpn, qp->send.psn );

 		/* Modify queue pair */
 		if ( ( rc = ib_modify_qp ( ibdev, qp ) ) != 0 ) {
 			DBGC ( conn, "CM %p could not modify queue pair: %s\n",
 			       conn, strerror ( rc ) );
 			goto out;
 		}

 		/* Send "ready to use" reply */
 		if ( ( rc = ib_cm_send_rtu ( ibdev, mi, conn, av ) ) != 0 ) {
 			/* Treat as non-fatal */
 			rc = 0;
 		}
 		break;

 	case htons ( IB_CM_ATTR_CONNECT_REJECT ) :
 		/* Extract fields */
 		DBGC ( conn, "CM %p connection rejected (reason %d)\n",
 		       conn, ntohs ( connect_rej->reason ) );
 		/* Private data is valid only for a Consumer Reject */
 		if ( connect_rej->reason == htons ( IB_CM_REJECT_CONSUMER ) ) {
 			private_data = &connect_rej->private_data;
 			private_data_len = sizeof (connect_rej->private_data);
 		}
 		rc = ib_cm_rejection_reason_to_rc ( connect_rej->reason );
 		break;

 	default:
 		DBGC ( conn, "CM %p unexpected response (attribute %04x)\n",
 		       conn, ntohs ( mad->hdr.attr_id ) );
 		rc = -ENOTSUP;
 		break;
 	}

  out:
 	/* Destroy the completed transaction */
 	ib_destroy_madx ( ibdev, ibdev->gsi, madx );
 	conn->madx = NULL;

 	/* Hand off to the upper completion handler */
 	conn->op->changed ( ibdev, qp, conn, rc, private_data,
 			    private_data_len );
 }

 /** Connection request operations */
 static struct ib_mad_transaction_operations ib_cm_req_op = {
 	.complete = ib_cm_req_complete,
 };

 /**
  * Handle connection path transaction completion
  *
  * @v ibdev		Infiniband device
  * @v path		Path
  * @v rc		Status code
  * @v av		Address vector, or NULL on error
  */
 static void ib_cm_path_complete ( struct ib_device *ibdev,
 				  struct ib_path *path, int rc,
 				  struct ib_address_vector *av ) {
 	struct ib_connection *conn = ib_path_get_ownerdata ( path );
 	struct ib_queue_pair *qp = conn->qp;
 	union ib_mad mad;
 	struct ib_cm_connect_request *connect_req =
 		&mad.cm.cm_data.connect_request;
 	size_t private_data_len;

 	/* Report failures */
 	if ( rc != 0 ) {
 		DBGC ( conn, "CM %p path lookup failed: %s\n",
 		       conn, strerror ( rc ) );
 		conn->op->changed ( ibdev, qp, conn, rc, NULL, 0 );
 		goto out;
 	}

 	/* Update queue pair peer path */
 	memcpy ( &qp->av, av, sizeof ( qp->av ) );

 	/* Construct connection request */
 	memset ( &mad, 0, sizeof ( mad ) );
 	mad.hdr.mgmt_class = IB_MGMT_CLASS_CM;
 	mad.hdr.class_version = IB_CM_CLASS_VERSION;
 	mad.hdr.method = IB_MGMT_METHOD_SEND;
 	mad.hdr.attr_id = htons ( IB_CM_ATTR_CONNECT_REQUEST );
 	connect_req->local_id = htonl ( conn->local_id );
 	memcpy ( &connect_req->service_id, &conn->service_id,
 		 sizeof ( connect_req->service_id ) );
 	ib_get_hca_info ( ibdev, &connect_req->local_ca );
 	connect_req->local_qpn__responder_resources =
 		htonl ( ( qp->qpn << 8 ) | 1 );
 	connect_req->local_eecn__initiator_depth = htonl ( ( 0 << 8 ) | 1 );
 	connect_req->remote_eecn__remote_timeout__service_type__ee_flow_ctrl =
 		htonl ( ( 0x14 << 3 ) | ( IB_CM_TRANSPORT_RC << 1 ) |
 			( 0 << 0 ) );
 	connect_req->starting_psn__local_timeout__retry_count =
 		htonl ( ( qp->recv.psn << 8 ) | ( 0x14 << 3 ) |
 			( 0x07 << 0 ) );
 	connect_req->pkey = htons ( ibdev->pkey );
 	connect_req->payload_mtu__rdc_exists__rnr_retry =
 		( ( IB_MTU_2048 << 4 ) | ( 1 << 3 ) | ( 0x07 << 0 ) );
 	connect_req->max_cm_retries__srq =
 		( ( 0x0f << 4 ) | ( 0 << 3 ) );
 	connect_req->primary.local_lid = htons ( ibdev->lid );
 	connect_req->primary.remote_lid = htons ( conn->qp->av.lid );
 	memcpy ( &connect_req->primary.local_gid, &ibdev->gid,
 		 sizeof ( connect_req->primary.local_gid ) );
 	memcpy ( &connect_req->primary.remote_gid, &conn->qp->av.gid,
 		 sizeof ( connect_req->primary.remote_gid ) );
 	connect_req->primary.flow_label__rate =
 		htonl ( ( 0 << 12 ) | ( conn->qp->av.rate << 0 ) );
 	connect_req->primary.hop_limit = 0;
 	connect_req->primary.sl__subnet_local =
 		( ( conn->qp->av.sl << 4 ) | ( 1 << 3 ) );
 	connect_req->primary.local_ack_timeout = ( 0x13 << 3 );
 	private_data_len = conn->private_data_len;
 	if ( private_data_len > sizeof ( connect_req->private_data ) )
 		private_data_len = sizeof ( connect_req->private_data );
 	memcpy ( &connect_req->private_data, &conn->private_data,
 		 private_data_len );

 	/* Create connection request */
 	av->qpn = IB_QPN_GSI;
 	av->qkey = IB_QKEY_GSI;
 	conn->madx = ib_create_madx ( ibdev, ibdev->gsi, &mad, av,
 				      &ib_cm_req_op );
 	if ( ! conn->madx ) {
 		DBGC ( conn, "CM %p could not create connection request\n",
 		       conn );
 		conn->op->changed ( ibdev, qp, conn, rc, NULL, 0 );
 		goto out;
 	}
 	ib_madx_set_ownerdata ( conn->madx, conn );

  out:
 	/* Destroy the completed transaction */
 	ib_destroy_path ( ibdev, path );
 	conn->path = NULL;
 }

 /** Connection path operations */
 static struct ib_path_operations ib_cm_path_op = {
 	.complete = ib_cm_path_complete,
 };

 /**
  * Create connection to remote QP
  *
  * @v ibdev		Infiniband device
  * @v qp		Queue pair
  * @v dgid		Target GID
  * @v service_id	Target service ID
  * @v private_data	Connection request private data
  * @v private_data_len	Length of connection request private data
  * @v op		Connection operations
  * @ret conn		Connection
  */
 struct ib_connection *
 ib_create_conn ( struct ib_device *ibdev, struct ib_queue_pair *qp,
 		 struct ib_gid *dgid, struct ib_gid_half *service_id,
 		 void *private_data, size_t private_data_len,
 		 struct ib_connection_operations *op ) {
 	struct ib_connection *conn;

 	/* Allocate and initialise request */
 	conn = zalloc ( sizeof ( *conn ) + private_data_len );
 	if ( ! conn )
 		goto err_alloc_conn;
 	conn->ibdev = ibdev;
 	conn->qp = qp;
 	memset ( &qp->av, 0, sizeof ( qp->av ) );
 	qp->av.gid_present = 1;
 	memcpy ( &qp->av.gid, dgid, sizeof ( qp->av.gid ) );
 	conn->local_id = random();
 	memcpy ( &conn->service_id, service_id, sizeof ( conn->service_id ) );
 	conn->op = op;
 	conn->private_data_len = private_data_len;
 	memcpy ( &conn->private_data, private_data, private_data_len );

 	/* Create path */
 	conn->path = ib_create_path ( ibdev, &qp->av, &ib_cm_path_op );
 	if ( ! conn->path )
 		goto err_create_path;
 	ib_path_set_ownerdata ( conn->path, conn );

 	/* Add to list of connections */
 	list_add ( &conn->list, &ib_cm_conns );

 	DBGC ( conn, "CM %p created for IBDEV %p QPN %lx\n",
 	       conn, ibdev, qp->qpn );
 	DBGC ( conn, "CM %p connecting to %08x:%08x:%08x:%08x %08x:%08x\n",
 	       conn, ntohl ( dgid->u.dwords[0] ), ntohl ( dgid->u.dwords[1] ),
 	       ntohl ( dgid->u.dwords[2] ), ntohl ( dgid->u.dwords[3] ),
 	       ntohl ( service_id->u.dwords[0] ),
 	       ntohl ( service_id->u.dwords[1] ) );

 	return conn;

 	ib_destroy_path ( ibdev, conn->path );
  err_create_path:
 	free ( conn );
  err_alloc_conn:
 	return NULL;
 }

 /**
  * Destroy connection to remote QP
  *
  * @v ibdev		Infiniband device
  * @v qp		Queue pair
  * @v conn		Connection
  */
 void ib_destroy_conn ( struct ib_device *ibdev,
 		       struct ib_queue_pair *qp __unused,
 		       struct ib_connection *conn ) {

 	list_del ( &conn->list );
 	if ( conn->madx )
 		ib_destroy_madx ( ibdev, ibdev->gsi, conn->madx );
 	if ( conn->path )
 		ib_destroy_path ( ibdev, conn->path );
 	free ( conn );
 }
	/*
	* Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License as
	* published by the Free Software Foundation; either version 2 of the
	* License, or any later version.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*/

	FILE_LICENCE ( GPL2_OR_LATER );

	#include <stdint.h>
	#include <stdlib.h>
	#include <string.h>
	#include <byteswap.h>
	#include <errno.h>
	#include <assert.h>
	#include <gpxe/infiniband.h>
	#include <gpxe/ib_mi.h>
	#include <gpxe/ib_pathrec.h>
	#include <gpxe/ib_cm.h>

	/**
	* @file
	*
	* Infiniband communication management
	*
	*/

	/** List of connections */
	static LIST_HEAD ( ib_cm_conns );

	/**
	* Send "ready to use" response
	*
	* @v ibdev Infiniband device
	* @v mi Management interface
	* @v conn Connection
	* @v av Address vector
	* @ret rc Return status code
	*/
	static int ib_cm_send_rtu ( struct ib_device *ibdev,
	struct ib_mad_interface *mi,
	struct ib_connection *conn,
	struct ib_address_vector *av ) {
	union ib_mad mad;
	struct ib_cm_ready_to_use *ready =
	&mad.cm.cm_data.ready_to_use;
	int rc;

	/* Construct "ready to use" response */
	memset ( &mad, 0, sizeof ( mad ) );
	mad.hdr.mgmt_class = IB_MGMT_CLASS_CM;
	mad.hdr.class_version = IB_CM_CLASS_VERSION;
	mad.hdr.method = IB_MGMT_METHOD_SEND;
	mad.hdr.attr_id = htons ( IB_CM_ATTR_READY_TO_USE );
	ready->local_id = htonl ( conn->local_id );
	ready->remote_id = htonl ( conn->remote_id );
	if ( ( rc = ib_mi_send ( ibdev, mi, &mad, av ) ) != 0 ){
	DBGC ( conn, "CM %p could not send RTU: %s\n",
	conn, strerror ( rc ) );
	return rc;
	}

	return 0;
	}

	/**
	* Handle duplicate connection replies
	*
	* @v ibdev Infiniband device
	* @v mi Management interface
	* @v mad Received MAD
	* @v av Source address vector
	* @ret rc Return status code
	*
	* If a "ready to use" MAD is lost, the peer may resend the connection
	* reply. We have to respond to these with duplicate "ready to use"
	* MADs, otherwise the peer may time out and drop the connection.
	*/
	static void ib_cm_connect_rep ( struct ib_device *ibdev,
	struct ib_mad_interface *mi,
	union ib_mad *mad,
	struct ib_address_vector *av ) {
	struct ib_cm_connect_reply *connect_rep =
	&mad->cm.cm_data.connect_reply;
	struct ib_connection *conn;
	int rc;

	/* Identify connection */
	list_for_each_entry ( conn, &ib_cm_conns, list ) {
	if ( ntohl ( connect_rep->remote_id ) != conn->local_id )
	continue;
	/* Try to send "ready to use" reply */
	if ( ( rc = ib_cm_send_rtu ( ibdev, mi, conn, av ) ) != 0 ) {
	/* Ignore errors */
	return;
	}
	return;
	}

	DBG ( "CM unidentified connection %08x\n",
	ntohl ( connect_rep->remote_id ) );
	}

	/** Communication management agents */
	struct ib_mad_agent ib_cm_agent[] __ib_mad_agent = {
	{
	.mgmt_class = IB_MGMT_CLASS_CM,
	.class_version = IB_CM_CLASS_VERSION,
	.attr_id = htons ( IB_CM_ATTR_CONNECT_REPLY ),
	.handle = ib_cm_connect_rep,
	},
	};

	/**
	* Convert connection rejection reason to return status code
	*
	* @v reason Rejection reason (in network byte order)
	* @ret rc Return status code
	*/
	static int ib_cm_rejection_reason_to_rc ( uint16_t reason ) {
	switch ( reason ) {
	case htons ( IB_CM_REJECT_BAD_SERVICE_ID ) :
	return -ENODEV;
	case htons ( IB_CM_REJECT_STALE_CONN ) :
	return -EALREADY;
	case htons ( IB_CM_REJECT_CONSUMER ) :
	return -ENOTTY;
	default:
	return -EPERM;
	}
	}

	/**
	* Handle connection request transaction completion
	*
	* @v ibdev Infiniband device
	* @v mi Management interface
	* @v madx Management transaction
	* @v rc Status code
	* @v mad Received MAD (or NULL on error)
	* @v av Source address vector (or NULL on error)
	*/
	static void ib_cm_req_complete ( struct ib_device *ibdev,
	struct ib_mad_interface *mi,
	struct ib_mad_transaction *madx,
	int rc, union ib_mad *mad,
	struct ib_address_vector *av ) {
	struct ib_connection *conn = ib_madx_get_ownerdata ( madx );
	struct ib_queue_pair *qp = conn->qp;
	struct ib_cm_common *common = &mad->cm.cm_data.common;
	struct ib_cm_connect_reply *connect_rep =
	&mad->cm.cm_data.connect_reply;
	struct ib_cm_connect_reject *connect_rej =
	&mad->cm.cm_data.connect_reject;
	void *private_data = NULL;
	size_t private_data_len = 0;

	/* Report failures */
	if ( ( rc == 0 ) && ( mad->hdr.status != htons ( IB_MGMT_STATUS_OK ) ))
	rc = -EIO;
	if ( rc != 0 ) {
	DBGC ( conn, "CM %p connection request failed: %s\n",
	conn, strerror ( rc ) );
	goto out;
	}

	/* Record remote communication ID */
	conn->remote_id = ntohl ( common->local_id );

	/* Handle response */
	switch ( mad->hdr.attr_id ) {

	case htons ( IB_CM_ATTR_CONNECT_REPLY ) :
	/* Extract fields */
	qp->av.qpn = ( ntohl ( connect_rep->local_qpn ) >> 8 );
	qp->send.psn = ( ntohl ( connect_rep->starting_psn ) >> 8 );
	private_data = &connect_rep->private_data;
	private_data_len = sizeof ( connect_rep->private_data );
	DBGC ( conn, "CM %p connected to QPN %lx PSN %x\n",
	conn, qp->av.qpn, qp->send.psn );

	/* Modify queue pair */
	if ( ( rc = ib_modify_qp ( ibdev, qp ) ) != 0 ) {
	DBGC ( conn, "CM %p could not modify queue pair: %s\n",
	conn, strerror ( rc ) );
	goto out;
	}

	/* Send "ready to use" reply */
	if ( ( rc = ib_cm_send_rtu ( ibdev, mi, conn, av ) ) != 0 ) {
	/* Treat as non-fatal */
	rc = 0;
	}
	break;

	case htons ( IB_CM_ATTR_CONNECT_REJECT ) :
	/* Extract fields */
	DBGC ( conn, "CM %p connection rejected (reason %d)\n",
	conn, ntohs ( connect_rej->reason ) );
	/* Private data is valid only for a Consumer Reject */
	if ( connect_rej->reason == htons ( IB_CM_REJECT_CONSUMER ) ) {
	private_data = &connect_rej->private_data;
	private_data_len = sizeof (connect_rej->private_data);
	}
	rc = ib_cm_rejection_reason_to_rc ( connect_rej->reason );
	break;

	default:
	DBGC ( conn, "CM %p unexpected response (attribute %04x)\n",
	conn, ntohs ( mad->hdr.attr_id ) );
	rc = -ENOTSUP;
	break;
	}

	out:
	/* Destroy the completed transaction */
	ib_destroy_madx ( ibdev, ibdev->gsi, madx );
	conn->madx = NULL;

	/* Hand off to the upper completion handler */
	conn->op->changed ( ibdev, qp, conn, rc, private_data,
	private_data_len );
	}

	/** Connection request operations */
	static struct ib_mad_transaction_operations ib_cm_req_op = {
	.complete = ib_cm_req_complete,
	};

	/**
	* Handle connection path transaction completion
	*
	* @v ibdev Infiniband device
	* @v path Path
	* @v rc Status code
	* @v av Address vector, or NULL on error
	*/
	static void ib_cm_path_complete ( struct ib_device *ibdev,
	struct ib_path *path, int rc,
	struct ib_address_vector *av ) {
	struct ib_connection *conn = ib_path_get_ownerdata ( path );
	struct ib_queue_pair *qp = conn->qp;
	union ib_mad mad;
	struct ib_cm_connect_request *connect_req =
	&mad.cm.cm_data.connect_request;
	size_t private_data_len;

	/* Report failures */
	if ( rc != 0 ) {
	DBGC ( conn, "CM %p path lookup failed: %s\n",
	conn, strerror ( rc ) );
	conn->op->changed ( ibdev, qp, conn, rc, NULL, 0 );
	goto out;
	}

	/* Update queue pair peer path */
	memcpy ( &qp->av, av, sizeof ( qp->av ) );

	/* Construct connection request */
	memset ( &mad, 0, sizeof ( mad ) );
	mad.hdr.mgmt_class = IB_MGMT_CLASS_CM;
	mad.hdr.class_version = IB_CM_CLASS_VERSION;
	mad.hdr.method = IB_MGMT_METHOD_SEND;
	mad.hdr.attr_id = htons ( IB_CM_ATTR_CONNECT_REQUEST );
	connect_req->local_id = htonl ( conn->local_id );
	memcpy ( &connect_req->service_id, &conn->service_id,
	sizeof ( connect_req->service_id ) );
	ib_get_hca_info ( ibdev, &connect_req->local_ca );
	connect_req->local_qpn__responder_resources =
	htonl ( ( qp->qpn << 8 ) \| 1 );
	connect_req->local_eecn__initiator_depth = htonl ( ( 0 << 8 ) \| 1 );
	connect_req->remote_eecn__remote_timeout__service_type__ee_flow_ctrl =
	htonl ( ( 0x14 << 3 ) \| ( IB_CM_TRANSPORT_RC << 1 ) \|
	( 0 << 0 ) );
	connect_req->starting_psn__local_timeout__retry_count =
	htonl ( ( qp->recv.psn << 8 ) \| ( 0x14 << 3 ) \|
	( 0x07 << 0 ) );
	connect_req->pkey = htons ( ibdev->pkey );
	connect_req->payload_mtu__rdc_exists__rnr_retry =
	( ( IB_MTU_2048 << 4 ) \| ( 1 << 3 ) \| ( 0x07 << 0 ) );
	connect_req->max_cm_retries__srq =
	( ( 0x0f << 4 ) \| ( 0 << 3 ) );
	connect_req->primary.local_lid = htons ( ibdev->lid );
	connect_req->primary.remote_lid = htons ( conn->qp->av.lid );
	memcpy ( &connect_req->primary.local_gid, &ibdev->gid,
	sizeof ( connect_req->primary.local_gid ) );
	memcpy ( &connect_req->primary.remote_gid, &conn->qp->av.gid,
	sizeof ( connect_req->primary.remote_gid ) );
	connect_req->primary.flow_label__rate =
	htonl ( ( 0 << 12 ) \| ( conn->qp->av.rate << 0 ) );
	connect_req->primary.hop_limit = 0;
	connect_req->primary.sl__subnet_local =
	( ( conn->qp->av.sl << 4 ) \| ( 1 << 3 ) );
	connect_req->primary.local_ack_timeout = ( 0x13 << 3 );
	private_data_len = conn->private_data_len;
	if ( private_data_len > sizeof ( connect_req->private_data ) )
	private_data_len = sizeof ( connect_req->private_data );
	memcpy ( &connect_req->private_data, &conn->private_data,
	private_data_len );

	/* Create connection request */
	av->qpn = IB_QPN_GSI;
	av->qkey = IB_QKEY_GSI;
	conn->madx = ib_create_madx ( ibdev, ibdev->gsi, &mad, av,
	&ib_cm_req_op );
	if ( ! conn->madx ) {
	DBGC ( conn, "CM %p could not create connection request\n",
	conn );
	conn->op->changed ( ibdev, qp, conn, rc, NULL, 0 );
	goto out;
	}
	ib_madx_set_ownerdata ( conn->madx, conn );

	out:
	/* Destroy the completed transaction */
	ib_destroy_path ( ibdev, path );
	conn->path = NULL;
	}

	/** Connection path operations */
	static struct ib_path_operations ib_cm_path_op = {
	.complete = ib_cm_path_complete,
	};

	/**
	* Create connection to remote QP
	*
	* @v ibdev Infiniband device
	* @v qp Queue pair
	* @v dgid Target GID
	* @v service_id Target service ID
	* @v private_data Connection request private data
	* @v private_data_len Length of connection request private data
	* @v op Connection operations
	* @ret conn Connection
	*/
	struct ib_connection *
	ib_create_conn ( struct ib_device ibdev, struct ib_queue_pair qp,
	struct ib_gid dgid, struct ib_gid_half service_id,
	void *private_data, size_t private_data_len,
	struct ib_connection_operations *op ) {
	struct ib_connection *conn;

	/* Allocate and initialise request */
	conn = zalloc ( sizeof ( *conn ) + private_data_len );
	if ( ! conn )
	goto err_alloc_conn;
	conn->ibdev = ibdev;
	conn->qp = qp;
	memset ( &qp->av, 0, sizeof ( qp->av ) );
	qp->av.gid_present = 1;
	memcpy ( &qp->av.gid, dgid, sizeof ( qp->av.gid ) );
	conn->local_id = random();
	memcpy ( &conn->service_id, service_id, sizeof ( conn->service_id ) );
	conn->op = op;
	conn->private_data_len = private_data_len;
	memcpy ( &conn->private_data, private_data, private_data_len );

	/* Create path */
	conn->path = ib_create_path ( ibdev, &qp->av, &ib_cm_path_op );
	if ( ! conn->path )
	goto err_create_path;
	ib_path_set_ownerdata ( conn->path, conn );

	/* Add to list of connections */
	list_add ( &conn->list, &ib_cm_conns );

	DBGC ( conn, "CM %p created for IBDEV %p QPN %lx\n",
	conn, ibdev, qp->qpn );
	DBGC ( conn, "CM %p connecting to %08x:%08x:%08x:%08x %08x:%08x\n",
	conn, ntohl ( dgid->u.dwords[0] ), ntohl ( dgid->u.dwords[1] ),
	ntohl ( dgid->u.dwords[2] ), ntohl ( dgid->u.dwords[3] ),
	ntohl ( service_id->u.dwords[0] ),
	ntohl ( service_id->u.dwords[1] ) );

	return conn;

	ib_destroy_path ( ibdev, conn->path );
	err_create_path:
	free ( conn );
	err_alloc_conn:
	return NULL;
	}

	/**
	* Destroy connection to remote QP
	*
	* @v ibdev Infiniband device
	* @v qp Queue pair
	* @v conn Connection
	*/
	void ib_destroy_conn ( struct ib_device *ibdev,
	struct ib_queue_pair *qp __unused,
	struct ib_connection *conn ) {

	list_del ( &conn->list );
	if ( conn->madx )
	ib_destroy_madx ( ibdev, ibdev->gsi, conn->madx );
	if ( conn->path )
	ib_destroy_path ( ibdev, conn->path );
	free ( conn );
	}