4 files changed, 1212 insertions, 0 deletions

diff --git a/drivers/target/loopback/Kconfig b/drivers/target/loopback/Kconfig
new file mode 100644
index 0000000000..f40f316073
--- /dev/null
+++ b/drivers/target/loopback/Kconfig
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config LOOPBACK_TARGET
+	tristate "TCM Virtual SAS target and Linux/SCSI LDD fabric loopback module"
+	depends on SCSI
+	help
+	  Say Y here to enable the TCM Virtual SAS target and Linux/SCSI LLD
+	  fabric loopback module.
diff --git a/drivers/target/loopback/Makefile b/drivers/target/loopback/Makefile
new file mode 100644
index 0000000000..336bd44bf9
--- /dev/null
+++ b/drivers/target/loopback/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_LOOPBACK_TARGET)	+= tcm_loop.o
diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c
new file mode 100644
index 0000000000..4ec99a55ac
--- /dev/null
+++ b/drivers/target/loopback/tcm_loop.c
@@ -0,0 +1,1149 @@
+/*******************************************************************************
+ *
+ * This file contains the Linux/SCSI LLD virtual SCSI initiator driver
+ * for emulated SAS initiator ports
+ *
+ * © Copyright 2011-2013 Datera, Inc.
+ *
+ * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
+ *
+ * Author: Nicholas A. Bellinger <nab@risingtidesystems.com>
+ *
+ * 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
+ * (at your option) 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.
+ ****************************************************************************/
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/configfs.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_tcq.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_cmnd.h>
+
+#include <target/target_core_base.h>
+#include <target/target_core_fabric.h>
+
+#include "tcm_loop.h"
+
+#define to_tcm_loop_hba(hba)	container_of(hba, struct tcm_loop_hba, dev)
+
+static struct kmem_cache *tcm_loop_cmd_cache;
+
+static int tcm_loop_hba_no_cnt;
+
+static int tcm_loop_queue_status(struct se_cmd *se_cmd);
+
+static unsigned int tcm_loop_nr_hw_queues = 1;
+module_param_named(nr_hw_queues, tcm_loop_nr_hw_queues, uint, 0644);
+
+static unsigned int tcm_loop_can_queue = 1024;
+module_param_named(can_queue, tcm_loop_can_queue, uint, 0644);
+
+static unsigned int tcm_loop_cmd_per_lun = 1024;
+module_param_named(cmd_per_lun, tcm_loop_cmd_per_lun, uint, 0644);
+
+/*
+ * Called from struct target_core_fabric_ops->check_stop_free()
+ */
+static int tcm_loop_check_stop_free(struct se_cmd *se_cmd)
+{
+	return transport_generic_free_cmd(se_cmd, 0);
+}
+
+static void tcm_loop_release_cmd(struct se_cmd *se_cmd)
+{
+	struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
+				struct tcm_loop_cmd, tl_se_cmd);
+	struct scsi_cmnd *sc = tl_cmd->sc;
+
+	if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
+		kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
+	else
+		scsi_done(sc);
+}
+
+static int tcm_loop_show_info(struct seq_file *m, struct Scsi_Host *host)
+{
+	seq_puts(m, "tcm_loop_proc_info()\n");
+	return 0;
+}
+
+static int tcm_loop_driver_probe(struct device *);
+static void tcm_loop_driver_remove(struct device *);
+
+static struct bus_type tcm_loop_lld_bus = {
+	.name			= "tcm_loop_bus",
+	.probe			= tcm_loop_driver_probe,
+	.remove			= tcm_loop_driver_remove,
+};
+
+static struct device_driver tcm_loop_driverfs = {
+	.name			= "tcm_loop",
+	.bus			= &tcm_loop_lld_bus,
+};
+/*
+ * Used with root_device_register() in tcm_loop_alloc_core_bus() below
+ */
+static struct device *tcm_loop_primary;
+
+static void tcm_loop_target_queue_cmd(struct tcm_loop_cmd *tl_cmd)
+{
+	struct se_cmd *se_cmd = &tl_cmd->tl_se_cmd;
+	struct scsi_cmnd *sc = tl_cmd->sc;
+	struct tcm_loop_nexus *tl_nexus;
+	struct tcm_loop_hba *tl_hba;
+	struct tcm_loop_tpg *tl_tpg;
+	struct scatterlist *sgl_bidi = NULL;
+	u32 sgl_bidi_count = 0, transfer_length;
+
+	tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
+	tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
+
+	/*
+	 * Ensure that this tl_tpg reference from the incoming sc->device->id
+	 * has already been configured via tcm_loop_make_naa_tpg().
+	 */
+	if (!tl_tpg->tl_hba) {
+		set_host_byte(sc, DID_NO_CONNECT);
+		goto out_done;
+	}
+	if (tl_tpg->tl_transport_status == TCM_TRANSPORT_OFFLINE) {
+		set_host_byte(sc, DID_TRANSPORT_DISRUPTED);
+		goto out_done;
+	}
+	tl_nexus = tl_tpg->tl_nexus;
+	if (!tl_nexus) {
+		scmd_printk(KERN_ERR, sc,
+			    "TCM_Loop I_T Nexus does not exist\n");
+		set_host_byte(sc, DID_ERROR);
+		goto out_done;
+	}
+
+	transfer_length = scsi_transfer_length(sc);
+	if (!scsi_prot_sg_count(sc) &&
+	    scsi_get_prot_op(sc) != SCSI_PROT_NORMAL) {
+		se_cmd->prot_pto = true;
+		/*
+		 * loopback transport doesn't support
+		 * WRITE_GENERATE, READ_STRIP protection
+		 * information operations, go ahead unprotected.
+		 */
+		transfer_length = scsi_bufflen(sc);
+	}
+
+	se_cmd->tag = tl_cmd->sc_cmd_tag;
+	target_init_cmd(se_cmd, tl_nexus->se_sess, &tl_cmd->tl_sense_buf[0],
+			tl_cmd->sc->device->lun, transfer_length,
+			TCM_SIMPLE_TAG, sc->sc_data_direction, 0);
+
+	if (target_submit_prep(se_cmd, sc->cmnd, scsi_sglist(sc),
+			       scsi_sg_count(sc), sgl_bidi, sgl_bidi_count,
+			       scsi_prot_sglist(sc), scsi_prot_sg_count(sc),
+			       GFP_ATOMIC))
+		return;
+
+	target_queue_submission(se_cmd);
+	return;
+
+out_done:
+	scsi_done(sc);
+}
+
+/*
+ * ->queuecommand can be and usually is called from interrupt context, so
+ * defer the actual submission to a workqueue.
+ */
+static int tcm_loop_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc)
+{
+	struct tcm_loop_cmd *tl_cmd = scsi_cmd_priv(sc);
+
+	pr_debug("%s() %d:%d:%d:%llu got CDB: 0x%02x scsi_buf_len: %u\n",
+		 __func__, sc->device->host->host_no, sc->device->id,
+		 sc->device->channel, sc->device->lun, sc->cmnd[0],
+		 scsi_bufflen(sc));
+
+	memset(tl_cmd, 0, sizeof(*tl_cmd));
+	tl_cmd->sc = sc;
+	tl_cmd->sc_cmd_tag = scsi_cmd_to_rq(sc)->tag;
+
+	tcm_loop_target_queue_cmd(tl_cmd);
+	return 0;
+}
+
+/*
+ * Called from SCSI EH process context to issue a LUN_RESET TMR
+ * to struct scsi_device
+ */
+static int tcm_loop_issue_tmr(struct tcm_loop_tpg *tl_tpg,
+			      u64 lun, int task, enum tcm_tmreq_table tmr)
+{
+	struct se_cmd *se_cmd;
+	struct se_session *se_sess;
+	struct tcm_loop_nexus *tl_nexus;
+	struct tcm_loop_cmd *tl_cmd;
+	int ret = TMR_FUNCTION_FAILED, rc;
+
+	/*
+	 * Locate the tl_nexus and se_sess pointers
+	 */
+	tl_nexus = tl_tpg->tl_nexus;
+	if (!tl_nexus) {
+		pr_err("Unable to perform device reset without active I_T Nexus\n");
+		return ret;
+	}
+
+	tl_cmd = kmem_cache_zalloc(tcm_loop_cmd_cache, GFP_KERNEL);
+	if (!tl_cmd)
+		return ret;
+
+	init_completion(&tl_cmd->tmr_done);
+
+	se_cmd = &tl_cmd->tl_se_cmd;
+	se_sess = tl_tpg->tl_nexus->se_sess;
+
+	rc = target_submit_tmr(se_cmd, se_sess, tl_cmd->tl_sense_buf, lun,
+			       NULL, tmr, GFP_KERNEL, task,
+			       TARGET_SCF_ACK_KREF);
+	if (rc < 0)
+		goto release;
+	wait_for_completion(&tl_cmd->tmr_done);
+	ret = se_cmd->se_tmr_req->response;
+	target_put_sess_cmd(se_cmd);
+
+out:
+	return ret;
+
+release:
+	kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
+	goto out;
+}
+
+static int tcm_loop_abort_task(struct scsi_cmnd *sc)
+{
+	struct tcm_loop_hba *tl_hba;
+	struct tcm_loop_tpg *tl_tpg;
+	int ret;
+
+	/*
+	 * Locate the tcm_loop_hba_t pointer
+	 */
+	tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
+	tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
+	ret = tcm_loop_issue_tmr(tl_tpg, sc->device->lun,
+				 scsi_cmd_to_rq(sc)->tag, TMR_ABORT_TASK);
+	return (ret == TMR_FUNCTION_COMPLETE) ? SUCCESS : FAILED;
+}
+
+/*
+ * Called from SCSI EH process context to issue a LUN_RESET TMR
+ * to struct scsi_device
+ */
+static int tcm_loop_device_reset(struct scsi_cmnd *sc)
+{
+	struct tcm_loop_hba *tl_hba;
+	struct tcm_loop_tpg *tl_tpg;
+	int ret;
+
+	/*
+	 * Locate the tcm_loop_hba_t pointer
+	 */
+	tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
+	tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
+
+	ret = tcm_loop_issue_tmr(tl_tpg, sc->device->lun,
+				 0, TMR_LUN_RESET);
+	return (ret == TMR_FUNCTION_COMPLETE) ? SUCCESS : FAILED;
+}
+
+static int tcm_loop_target_reset(struct scsi_cmnd *sc)
+{
+	struct tcm_loop_hba *tl_hba;
+	struct tcm_loop_tpg *tl_tpg;
+
+	/*
+	 * Locate the tcm_loop_hba_t pointer
+	 */
+	tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
+	if (!tl_hba) {
+		pr_err("Unable to perform device reset without active I_T Nexus\n");
+		return FAILED;
+	}
+	/*
+	 * Locate the tl_tpg pointer from TargetID in sc->device->id
+	 */
+	tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
+	if (tl_tpg) {
+		tl_tpg->tl_transport_status = TCM_TRANSPORT_ONLINE;
+		return SUCCESS;
+	}
+	return FAILED;
+}
+
+static const struct scsi_host_template tcm_loop_driver_template = {
+	.show_info		= tcm_loop_show_info,
+	.proc_name		= "tcm_loopback",
+	.name			= "TCM_Loopback",
+	.queuecommand		= tcm_loop_queuecommand,
+	.change_queue_depth	= scsi_change_queue_depth,
+	.eh_abort_handler = tcm_loop_abort_task,
+	.eh_device_reset_handler = tcm_loop_device_reset,
+	.eh_target_reset_handler = tcm_loop_target_reset,
+	.this_id		= -1,
+	.sg_tablesize		= 256,
+	.max_sectors		= 0xFFFF,
+	.dma_boundary		= PAGE_SIZE - 1,
+	.module			= THIS_MODULE,
+	.track_queue_depth	= 1,
+	.cmd_size		= sizeof(struct tcm_loop_cmd),
+};
+
+static int tcm_loop_driver_probe(struct device *dev)
+{
+	struct tcm_loop_hba *tl_hba;
+	struct Scsi_Host *sh;
+	int error, host_prot;
+
+	tl_hba = to_tcm_loop_hba(dev);
+
+	sh = scsi_host_alloc(&tcm_loop_driver_template,
+			sizeof(struct tcm_loop_hba));
+	if (!sh) {
+		pr_err("Unable to allocate struct scsi_host\n");
+		return -ENODEV;
+	}
+	tl_hba->sh = sh;
+
+	/*
+	 * Assign the struct tcm_loop_hba pointer to struct Scsi_Host->hostdata
+	 */
+	*((struct tcm_loop_hba **)sh->hostdata) = tl_hba;
+	/*
+	 * Setup single ID, Channel and LUN for now..
+	 */
+	sh->max_id = 2;
+	sh->max_lun = 0;
+	sh->max_channel = 0;
+	sh->max_cmd_len = SCSI_MAX_VARLEN_CDB_SIZE;
+	sh->nr_hw_queues = tcm_loop_nr_hw_queues;
+	sh->can_queue = tcm_loop_can_queue;
+	sh->cmd_per_lun = tcm_loop_cmd_per_lun;
+
+	host_prot = SHOST_DIF_TYPE1_PROTECTION | SHOST_DIF_TYPE2_PROTECTION |
+		    SHOST_DIF_TYPE3_PROTECTION | SHOST_DIX_TYPE1_PROTECTION |
+		    SHOST_DIX_TYPE2_PROTECTION | SHOST_DIX_TYPE3_PROTECTION;
+
+	scsi_host_set_prot(sh, host_prot);
+	scsi_host_set_guard(sh, SHOST_DIX_GUARD_CRC);
+
+	error = scsi_add_host(sh, &tl_hba->dev);
+	if (error) {
+		pr_err("%s: scsi_add_host failed\n", __func__);
+		scsi_host_put(sh);
+		return -ENODEV;
+	}
+	return 0;
+}
+
+static void tcm_loop_driver_remove(struct device *dev)
+{
+	struct tcm_loop_hba *tl_hba;
+	struct Scsi_Host *sh;
+
+	tl_hba = to_tcm_loop_hba(dev);
+	sh = tl_hba->sh;
+
+	scsi_remove_host(sh);
+	scsi_host_put(sh);
+}
+
+static void tcm_loop_release_adapter(struct device *dev)
+{
+	struct tcm_loop_hba *tl_hba = to_tcm_loop_hba(dev);
+
+	kfree(tl_hba);
+}
+
+/*
+ * Called from tcm_loop_make_scsi_hba() in tcm_loop_configfs.c
+ */
+static int tcm_loop_setup_hba_bus(struct tcm_loop_hba *tl_hba, int tcm_loop_host_id)
+{
+	int ret;
+
+	tl_hba->dev.bus = &tcm_loop_lld_bus;
+	tl_hba->dev.parent = tcm_loop_primary;
+	tl_hba->dev.release = &tcm_loop_release_adapter;
+	dev_set_name(&tl_hba->dev, "tcm_loop_adapter_%d", tcm_loop_host_id);
+
+	ret = device_register(&tl_hba->dev);
+	if (ret) {
+		pr_err("device_register() failed for tl_hba->dev: %d\n", ret);
+		put_device(&tl_hba->dev);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+/*
+ * Called from tcm_loop_fabric_init() in tcl_loop_fabric.c to load the emulated
+ * tcm_loop SCSI bus.
+ */
+static int tcm_loop_alloc_core_bus(void)
+{
+	int ret;
+
+	tcm_loop_primary = root_device_register("tcm_loop_0");
+	if (IS_ERR(tcm_loop_primary)) {
+		pr_err("Unable to allocate tcm_loop_primary\n");
+		return PTR_ERR(tcm_loop_primary);
+	}
+
+	ret = bus_register(&tcm_loop_lld_bus);
+	if (ret) {
+		pr_err("bus_register() failed for tcm_loop_lld_bus\n");
+		goto dev_unreg;
+	}
+
+	ret = driver_register(&tcm_loop_driverfs);
+	if (ret) {
+		pr_err("driver_register() failed for tcm_loop_driverfs\n");
+		goto bus_unreg;
+	}
+
+	pr_debug("Initialized TCM Loop Core Bus\n");
+	return ret;
+
+bus_unreg:
+	bus_unregister(&tcm_loop_lld_bus);
+dev_unreg:
+	root_device_unregister(tcm_loop_primary);
+	return ret;
+}
+
+static void tcm_loop_release_core_bus(void)
+{
+	driver_unregister(&tcm_loop_driverfs);
+	bus_unregister(&tcm_loop_lld_bus);
+	root_device_unregister(tcm_loop_primary);
+
+	pr_debug("Releasing TCM Loop Core BUS\n");
+}
+
+static inline struct tcm_loop_tpg *tl_tpg(struct se_portal_group *se_tpg)
+{
+	return container_of(se_tpg, struct tcm_loop_tpg, tl_se_tpg);
+}
+
+static char *tcm_loop_get_endpoint_wwn(struct se_portal_group *se_tpg)
+{
+	/*
+	 * Return the passed NAA identifier for the Target Port
+	 */
+	return &tl_tpg(se_tpg)->tl_hba->tl_wwn_address[0];
+}
+
+static u16 tcm_loop_get_tag(struct se_portal_group *se_tpg)
+{
+	/*
+	 * This Tag is used when forming SCSI Name identifier in EVPD=1 0x83
+	 * to represent the SCSI Target Port.
+	 */
+	return tl_tpg(se_tpg)->tl_tpgt;
+}
+
+/*
+ * Returning (1) here allows for target_core_mod struct se_node_acl to be generated
+ * based upon the incoming fabric dependent SCSI Initiator Port
+ */
+static int tcm_loop_check_demo_mode(struct se_portal_group *se_tpg)
+{
+	return 1;
+}
+
+static int tcm_loop_check_prot_fabric_only(struct se_portal_group *se_tpg)
+{
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg, struct tcm_loop_tpg,
+						   tl_se_tpg);
+	return tl_tpg->tl_fabric_prot_type;
+}
+
+static u32 tcm_loop_sess_get_index(struct se_session *se_sess)
+{
+	return 1;
+}
+
+static int tcm_loop_get_cmd_state(struct se_cmd *se_cmd)
+{
+	struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
+			struct tcm_loop_cmd, tl_se_cmd);
+
+	return tl_cmd->sc_cmd_state;
+}
+
+static int tcm_loop_write_pending(struct se_cmd *se_cmd)
+{
+	/*
+	 * Since Linux/SCSI has already sent down a struct scsi_cmnd
+	 * sc->sc_data_direction of DMA_TO_DEVICE with struct scatterlist array
+	 * memory, and memory has already been mapped to struct se_cmd->t_mem_list
+	 * format with transport_generic_map_mem_to_cmd().
+	 *
+	 * We now tell TCM to add this WRITE CDB directly into the TCM storage
+	 * object execution queue.
+	 */
+	target_execute_cmd(se_cmd);
+	return 0;
+}
+
+static int tcm_loop_queue_data_or_status(const char *func,
+		struct se_cmd *se_cmd, u8 scsi_status)
+{
+	struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
+				struct tcm_loop_cmd, tl_se_cmd);
+	struct scsi_cmnd *sc = tl_cmd->sc;
+
+	pr_debug("%s() called for scsi_cmnd: %p cdb: 0x%02x\n",
+		 func, sc, sc->cmnd[0]);
+
+	if (se_cmd->sense_buffer &&
+	   ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
+	    (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE))) {
+
+		memcpy(sc->sense_buffer, se_cmd->sense_buffer,
+				SCSI_SENSE_BUFFERSIZE);
+		sc->result = SAM_STAT_CHECK_CONDITION;
+	} else
+		sc->result = scsi_status;
+
+	set_host_byte(sc, DID_OK);
+	if ((se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) ||
+	    (se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT))
+		scsi_set_resid(sc, se_cmd->residual_count);
+	return 0;
+}
+
+static int tcm_loop_queue_data_in(struct se_cmd *se_cmd)
+{
+	return tcm_loop_queue_data_or_status(__func__, se_cmd, SAM_STAT_GOOD);
+}
+
+static int tcm_loop_queue_status(struct se_cmd *se_cmd)
+{
+	return tcm_loop_queue_data_or_status(__func__,
+					     se_cmd, se_cmd->scsi_status);
+}
+
+static void tcm_loop_queue_tm_rsp(struct se_cmd *se_cmd)
+{
+	struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
+				struct tcm_loop_cmd, tl_se_cmd);
+
+	/* Wake up tcm_loop_issue_tmr(). */
+	complete(&tl_cmd->tmr_done);
+}
+
+static void tcm_loop_aborted_task(struct se_cmd *se_cmd)
+{
+	return;
+}
+
+static char *tcm_loop_dump_proto_id(struct tcm_loop_hba *tl_hba)
+{
+	switch (tl_hba->tl_proto_id) {
+	case SCSI_PROTOCOL_SAS:
+		return "SAS";
+	case SCSI_PROTOCOL_FCP:
+		return "FCP";
+	case SCSI_PROTOCOL_ISCSI:
+		return "iSCSI";
+	default:
+		break;
+	}
+
+	return "Unknown";
+}
+
+/* Start items for tcm_loop_port_cit */
+
+static int tcm_loop_port_link(
+	struct se_portal_group *se_tpg,
+	struct se_lun *lun)
+{
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
+				struct tcm_loop_tpg, tl_se_tpg);
+	struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
+
+	atomic_inc_mb(&tl_tpg->tl_tpg_port_count);
+	/*
+	 * Add Linux/SCSI struct scsi_device by HCTL
+	 */
+	scsi_add_device(tl_hba->sh, 0, tl_tpg->tl_tpgt, lun->unpacked_lun);
+
+	pr_debug("TCM_Loop_ConfigFS: Port Link Successful\n");
+	return 0;
+}
+
+static void tcm_loop_port_unlink(
+	struct se_portal_group *se_tpg,
+	struct se_lun *se_lun)
+{
+	struct scsi_device *sd;
+	struct tcm_loop_hba *tl_hba;
+	struct tcm_loop_tpg *tl_tpg;
+
+	tl_tpg = container_of(se_tpg, struct tcm_loop_tpg, tl_se_tpg);
+	tl_hba = tl_tpg->tl_hba;
+
+	sd = scsi_device_lookup(tl_hba->sh, 0, tl_tpg->tl_tpgt,
+				se_lun->unpacked_lun);
+	if (!sd) {
+		pr_err("Unable to locate struct scsi_device for %d:%d:%llu\n",
+		       0, tl_tpg->tl_tpgt, se_lun->unpacked_lun);
+		return;
+	}
+	/*
+	 * Remove Linux/SCSI struct scsi_device by HCTL
+	 */
+	scsi_remove_device(sd);
+	scsi_device_put(sd);
+
+	atomic_dec_mb(&tl_tpg->tl_tpg_port_count);
+
+	pr_debug("TCM_Loop_ConfigFS: Port Unlink Successful\n");
+}
+
+/* End items for tcm_loop_port_cit */
+
+static ssize_t tcm_loop_tpg_attrib_fabric_prot_type_show(
+		struct config_item *item, char *page)
+{
+	struct se_portal_group *se_tpg = attrib_to_tpg(item);
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg, struct tcm_loop_tpg,
+						   tl_se_tpg);
+
+	return sprintf(page, "%d\n", tl_tpg->tl_fabric_prot_type);
+}
+
+static ssize_t tcm_loop_tpg_attrib_fabric_prot_type_store(
+		struct config_item *item, const char *page, size_t count)
+{
+	struct se_portal_group *se_tpg = attrib_to_tpg(item);
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg, struct tcm_loop_tpg,
+						   tl_se_tpg);
+	unsigned long val;
+	int ret = kstrtoul(page, 0, &val);
+
+	if (ret) {
+		pr_err("kstrtoul() returned %d for fabric_prot_type\n", ret);
+		return ret;
+	}
+	if (val != 0 && val != 1 && val != 3) {
+		pr_err("Invalid qla2xxx fabric_prot_type: %lu\n", val);
+		return -EINVAL;
+	}
+	tl_tpg->tl_fabric_prot_type = val;
+
+	return count;
+}
+
+CONFIGFS_ATTR(tcm_loop_tpg_attrib_, fabric_prot_type);
+
+static struct configfs_attribute *tcm_loop_tpg_attrib_attrs[] = {
+	&tcm_loop_tpg_attrib_attr_fabric_prot_type,
+	NULL,
+};
+
+/* Start items for tcm_loop_nexus_cit */
+
+static int tcm_loop_alloc_sess_cb(struct se_portal_group *se_tpg,
+				  struct se_session *se_sess, void *p)
+{
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
+					struct tcm_loop_tpg, tl_se_tpg);
+
+	tl_tpg->tl_nexus = p;
+	return 0;
+}
+
+static int tcm_loop_make_nexus(
+	struct tcm_loop_tpg *tl_tpg,
+	const char *name)
+{
+	struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
+	struct tcm_loop_nexus *tl_nexus;
+	int ret;
+
+	if (tl_tpg->tl_nexus) {
+		pr_debug("tl_tpg->tl_nexus already exists\n");
+		return -EEXIST;
+	}
+
+	tl_nexus = kzalloc(sizeof(*tl_nexus), GFP_KERNEL);
+	if (!tl_nexus)
+		return -ENOMEM;
+
+	tl_nexus->se_sess = target_setup_session(&tl_tpg->tl_se_tpg, 0, 0,
+					TARGET_PROT_DIN_PASS | TARGET_PROT_DOUT_PASS,
+					name, tl_nexus, tcm_loop_alloc_sess_cb);
+	if (IS_ERR(tl_nexus->se_sess)) {
+		ret = PTR_ERR(tl_nexus->se_sess);
+		kfree(tl_nexus);
+		return ret;
+	}
+
+	pr_debug("TCM_Loop_ConfigFS: Established I_T Nexus to emulated %s Initiator Port: %s\n",
+		 tcm_loop_dump_proto_id(tl_hba), name);
+	return 0;
+}
+
+static int tcm_loop_drop_nexus(
+	struct tcm_loop_tpg *tpg)
+{
+	struct se_session *se_sess;
+	struct tcm_loop_nexus *tl_nexus;
+
+	tl_nexus = tpg->tl_nexus;
+	if (!tl_nexus)
+		return -ENODEV;
+
+	se_sess = tl_nexus->se_sess;
+	if (!se_sess)
+		return -ENODEV;
+
+	if (atomic_read(&tpg->tl_tpg_port_count)) {
+		pr_err("Unable to remove TCM_Loop I_T Nexus with active TPG port count: %d\n",
+		       atomic_read(&tpg->tl_tpg_port_count));
+		return -EPERM;
+	}
+
+	pr_debug("TCM_Loop_ConfigFS: Removing I_T Nexus to emulated %s Initiator Port: %s\n",
+		 tcm_loop_dump_proto_id(tpg->tl_hba),
+		 tl_nexus->se_sess->se_node_acl->initiatorname);
+	/*
+	 * Release the SCSI I_T Nexus to the emulated Target Port
+	 */
+	target_remove_session(se_sess);
+	tpg->tl_nexus = NULL;
+	kfree(tl_nexus);
+	return 0;
+}
+
+/* End items for tcm_loop_nexus_cit */
+
+static ssize_t tcm_loop_tpg_nexus_show(struct config_item *item, char *page)
+{
+	struct se_portal_group *se_tpg = to_tpg(item);
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
+			struct tcm_loop_tpg, tl_se_tpg);
+	struct tcm_loop_nexus *tl_nexus;
+	ssize_t ret;
+
+	tl_nexus = tl_tpg->tl_nexus;
+	if (!tl_nexus)
+		return -ENODEV;
+
+	ret = snprintf(page, PAGE_SIZE, "%s\n",
+		tl_nexus->se_sess->se_node_acl->initiatorname);
+
+	return ret;
+}
+
+static ssize_t tcm_loop_tpg_nexus_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct se_portal_group *se_tpg = to_tpg(item);
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
+			struct tcm_loop_tpg, tl_se_tpg);
+	struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
+	unsigned char i_port[TL_WWN_ADDR_LEN], *ptr, *port_ptr;
+	int ret;
+	/*
+	 * Shutdown the active I_T nexus if 'NULL' is passed..
+	 */
+	if (!strncmp(page, "NULL", 4)) {
+		ret = tcm_loop_drop_nexus(tl_tpg);
+		return (!ret) ? count : ret;
+	}
+	/*
+	 * Otherwise make sure the passed virtual Initiator port WWN matches
+	 * the fabric protocol_id set in tcm_loop_make_scsi_hba(), and call
+	 * tcm_loop_make_nexus()
+	 */
+	if (strlen(page) >= TL_WWN_ADDR_LEN) {
+		pr_err("Emulated NAA Sas Address: %s, exceeds max: %d\n",
+		       page, TL_WWN_ADDR_LEN);
+		return -EINVAL;
+	}
+	snprintf(&i_port[0], TL_WWN_ADDR_LEN, "%s", page);
+
+	ptr = strstr(i_port, "naa.");
+	if (ptr) {
+		if (tl_hba->tl_proto_id != SCSI_PROTOCOL_SAS) {
+			pr_err("Passed SAS Initiator Port %s does not match target port protoid: %s\n",
+			       i_port, tcm_loop_dump_proto_id(tl_hba));
+			return -EINVAL;
+		}
+		port_ptr = &i_port[0];
+		goto check_newline;
+	}
+	ptr = strstr(i_port, "fc.");
+	if (ptr) {
+		if (tl_hba->tl_proto_id != SCSI_PROTOCOL_FCP) {
+			pr_err("Passed FCP Initiator Port %s does not match target port protoid: %s\n",
+			       i_port, tcm_loop_dump_proto_id(tl_hba));
+			return -EINVAL;
+		}
+		port_ptr = &i_port[3]; /* Skip over "fc." */
+		goto check_newline;
+	}
+	ptr = strstr(i_port, "iqn.");
+	if (ptr) {
+		if (tl_hba->tl_proto_id != SCSI_PROTOCOL_ISCSI) {
+			pr_err("Passed iSCSI Initiator Port %s does not match target port protoid: %s\n",
+			       i_port, tcm_loop_dump_proto_id(tl_hba));
+			return -EINVAL;
+		}
+		port_ptr = &i_port[0];
+		goto check_newline;
+	}
+	pr_err("Unable to locate prefix for emulated Initiator Port: %s\n",
+	       i_port);
+	return -EINVAL;
+	/*
+	 * Clear any trailing newline for the NAA WWN
+	 */
+check_newline:
+	if (i_port[strlen(i_port)-1] == '\n')
+		i_port[strlen(i_port)-1] = '\0';
+
+	ret = tcm_loop_make_nexus(tl_tpg, port_ptr);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static ssize_t tcm_loop_tpg_transport_status_show(struct config_item *item,
+		char *page)
+{
+	struct se_portal_group *se_tpg = to_tpg(item);
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
+			struct tcm_loop_tpg, tl_se_tpg);
+	const char *status = NULL;
+	ssize_t ret = -EINVAL;
+
+	switch (tl_tpg->tl_transport_status) {
+	case TCM_TRANSPORT_ONLINE:
+		status = "online";
+		break;
+	case TCM_TRANSPORT_OFFLINE:
+		status = "offline";
+		break;
+	default:
+		break;
+	}
+
+	if (status)
+		ret = snprintf(page, PAGE_SIZE, "%s\n", status);
+
+	return ret;
+}
+
+static ssize_t tcm_loop_tpg_transport_status_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	struct se_portal_group *se_tpg = to_tpg(item);
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
+			struct tcm_loop_tpg, tl_se_tpg);
+
+	if (!strncmp(page, "online", 6)) {
+		tl_tpg->tl_transport_status = TCM_TRANSPORT_ONLINE;
+		return count;
+	}
+	if (!strncmp(page, "offline", 7)) {
+		tl_tpg->tl_transport_status = TCM_TRANSPORT_OFFLINE;
+		if (tl_tpg->tl_nexus) {
+			struct se_session *tl_sess = tl_tpg->tl_nexus->se_sess;
+
+			core_allocate_nexus_loss_ua(tl_sess->se_node_acl);
+		}
+		return count;
+	}
+	return -EINVAL;
+}
+
+static ssize_t tcm_loop_tpg_address_show(struct config_item *item,
+					 char *page)
+{
+	struct se_portal_group *se_tpg = to_tpg(item);
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
+			struct tcm_loop_tpg, tl_se_tpg);
+	struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
+
+	return snprintf(page, PAGE_SIZE, "%d:0:%d\n",
+			tl_hba->sh->host_no, tl_tpg->tl_tpgt);
+}
+
+CONFIGFS_ATTR(tcm_loop_tpg_, nexus);
+CONFIGFS_ATTR(tcm_loop_tpg_, transport_status);
+CONFIGFS_ATTR_RO(tcm_loop_tpg_, address);
+
+static struct configfs_attribute *tcm_loop_tpg_attrs[] = {
+	&tcm_loop_tpg_attr_nexus,
+	&tcm_loop_tpg_attr_transport_status,
+	&tcm_loop_tpg_attr_address,
+	NULL,
+};
+
+/* Start items for tcm_loop_naa_cit */
+
+static struct se_portal_group *tcm_loop_make_naa_tpg(struct se_wwn *wwn,
+						     const char *name)
+{
+	struct tcm_loop_hba *tl_hba = container_of(wwn,
+			struct tcm_loop_hba, tl_hba_wwn);
+	struct tcm_loop_tpg *tl_tpg;
+	int ret;
+	unsigned long tpgt;
+
+	if (strstr(name, "tpgt_") != name) {
+		pr_err("Unable to locate \"tpgt_#\" directory group\n");
+		return ERR_PTR(-EINVAL);
+	}
+	if (kstrtoul(name+5, 10, &tpgt))
+		return ERR_PTR(-EINVAL);
+
+	if (tpgt >= TL_TPGS_PER_HBA) {
+		pr_err("Passed tpgt: %lu exceeds TL_TPGS_PER_HBA: %u\n",
+		       tpgt, TL_TPGS_PER_HBA);
+		return ERR_PTR(-EINVAL);
+	}
+	tl_tpg = &tl_hba->tl_hba_tpgs[tpgt];
+	tl_tpg->tl_hba = tl_hba;
+	tl_tpg->tl_tpgt = tpgt;
+	/*
+	 * Register the tl_tpg as a emulated TCM Target Endpoint
+	 */
+	ret = core_tpg_register(wwn, &tl_tpg->tl_se_tpg, tl_hba->tl_proto_id);
+	if (ret < 0)
+		return ERR_PTR(-ENOMEM);
+
+	pr_debug("TCM_Loop_ConfigFS: Allocated Emulated %s Target Port %s,t,0x%04lx\n",
+		 tcm_loop_dump_proto_id(tl_hba),
+		 config_item_name(&wwn->wwn_group.cg_item), tpgt);
+	return &tl_tpg->tl_se_tpg;
+}
+
+static void tcm_loop_drop_naa_tpg(
+	struct se_portal_group *se_tpg)
+{
+	struct se_wwn *wwn = se_tpg->se_tpg_wwn;
+	struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
+				struct tcm_loop_tpg, tl_se_tpg);
+	struct tcm_loop_hba *tl_hba;
+	unsigned short tpgt;
+
+	tl_hba = tl_tpg->tl_hba;
+	tpgt = tl_tpg->tl_tpgt;
+	/*
+	 * Release the I_T Nexus for the Virtual target link if present
+	 */
+	tcm_loop_drop_nexus(tl_tpg);
+	/*
+	 * Deregister the tl_tpg as a emulated TCM Target Endpoint
+	 */
+	core_tpg_deregister(se_tpg);
+
+	tl_tpg->tl_hba = NULL;
+	tl_tpg->tl_tpgt = 0;
+
+	pr_debug("TCM_Loop_ConfigFS: Deallocated Emulated %s Target Port %s,t,0x%04x\n",
+		 tcm_loop_dump_proto_id(tl_hba),
+		 config_item_name(&wwn->wwn_group.cg_item), tpgt);
+}
+
+/* End items for tcm_loop_naa_cit */
+
+/* Start items for tcm_loop_cit */
+
+static struct se_wwn *tcm_loop_make_scsi_hba(
+	struct target_fabric_configfs *tf,
+	struct config_group *group,
+	const char *name)
+{
+	struct tcm_loop_hba *tl_hba;
+	struct Scsi_Host *sh;
+	char *ptr;
+	int ret, off = 0;
+
+	tl_hba = kzalloc(sizeof(*tl_hba), GFP_KERNEL);
+	if (!tl_hba)
+		return ERR_PTR(-ENOMEM);
+
+	/*
+	 * Determine the emulated Protocol Identifier and Target Port Name
+	 * based on the incoming configfs directory name.
+	 */
+	ptr = strstr(name, "naa.");
+	if (ptr) {
+		tl_hba->tl_proto_id = SCSI_PROTOCOL_SAS;
+		goto check_len;
+	}
+	ptr = strstr(name, "fc.");
+	if (ptr) {
+		tl_hba->tl_proto_id = SCSI_PROTOCOL_FCP;
+		off = 3; /* Skip over "fc." */
+		goto check_len;
+	}
+	ptr = strstr(name, "iqn.");
+	if (!ptr) {
+		pr_err("Unable to locate prefix for emulated Target Port: %s\n",
+		       name);
+		ret = -EINVAL;
+		goto out;
+	}
+	tl_hba->tl_proto_id = SCSI_PROTOCOL_ISCSI;
+
+check_len:
+	if (strlen(name) >= TL_WWN_ADDR_LEN) {
+		pr_err("Emulated NAA %s Address: %s, exceeds max: %d\n",
+		       name, tcm_loop_dump_proto_id(tl_hba), TL_WWN_ADDR_LEN);
+		ret = -EINVAL;
+		goto out;
+	}
+	snprintf(&tl_hba->tl_wwn_address[0], TL_WWN_ADDR_LEN, "%s", &name[off]);
+
+	/*
+	 * Call device_register(tl_hba->dev) to register the emulated
+	 * Linux/SCSI LLD of type struct Scsi_Host at tl_hba->sh after
+	 * device_register() callbacks in tcm_loop_driver_probe()
+	 */
+	ret = tcm_loop_setup_hba_bus(tl_hba, tcm_loop_hba_no_cnt);
+	if (ret)
+		return ERR_PTR(ret);
+
+	sh = tl_hba->sh;
+	tcm_loop_hba_no_cnt++;
+	pr_debug("TCM_Loop_ConfigFS: Allocated emulated Target %s Address: %s at Linux/SCSI Host ID: %d\n",
+		 tcm_loop_dump_proto_id(tl_hba), name, sh->host_no);
+	return &tl_hba->tl_hba_wwn;
+out:
+	kfree(tl_hba);
+	return ERR_PTR(ret);
+}
+
+static void tcm_loop_drop_scsi_hba(
+	struct se_wwn *wwn)
+{
+	struct tcm_loop_hba *tl_hba = container_of(wwn,
+				struct tcm_loop_hba, tl_hba_wwn);
+
+	pr_debug("TCM_Loop_ConfigFS: Deallocating emulated Target %s Address: %s at Linux/SCSI Host ID: %d\n",
+		 tcm_loop_dump_proto_id(tl_hba), tl_hba->tl_wwn_address,
+		 tl_hba->sh->host_no);
+	/*
+	 * Call device_unregister() on the original tl_hba->dev.
+	 * tcm_loop_fabric_scsi.c:tcm_loop_release_adapter() will
+	 * release *tl_hba;
+	 */
+	device_unregister(&tl_hba->dev);
+}
+
+/* Start items for tcm_loop_cit */
+static ssize_t tcm_loop_wwn_version_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "TCM Loopback Fabric module %s\n", TCM_LOOP_VERSION);
+}
+
+CONFIGFS_ATTR_RO(tcm_loop_wwn_, version);
+
+static struct configfs_attribute *tcm_loop_wwn_attrs[] = {
+	&tcm_loop_wwn_attr_version,
+	NULL,
+};
+
+/* End items for tcm_loop_cit */
+
+static const struct target_core_fabric_ops loop_ops = {
+	.module				= THIS_MODULE,
+	.fabric_name			= "loopback",
+	.tpg_get_wwn			= tcm_loop_get_endpoint_wwn,
+	.tpg_get_tag			= tcm_loop_get_tag,
+	.tpg_check_demo_mode		= tcm_loop_check_demo_mode,
+	.tpg_check_prot_fabric_only	= tcm_loop_check_prot_fabric_only,
+	.check_stop_free		= tcm_loop_check_stop_free,
+	.release_cmd			= tcm_loop_release_cmd,
+	.sess_get_index			= tcm_loop_sess_get_index,
+	.write_pending			= tcm_loop_write_pending,
+	.get_cmd_state			= tcm_loop_get_cmd_state,
+	.queue_data_in			= tcm_loop_queue_data_in,
+	.queue_status			= tcm_loop_queue_status,
+	.queue_tm_rsp			= tcm_loop_queue_tm_rsp,
+	.aborted_task			= tcm_loop_aborted_task,
+	.fabric_make_wwn		= tcm_loop_make_scsi_hba,
+	.fabric_drop_wwn		= tcm_loop_drop_scsi_hba,
+	.fabric_make_tpg		= tcm_loop_make_naa_tpg,
+	.fabric_drop_tpg		= tcm_loop_drop_naa_tpg,
+	.fabric_post_link		= tcm_loop_port_link,
+	.fabric_pre_unlink		= tcm_loop_port_unlink,
+	.tfc_wwn_attrs			= tcm_loop_wwn_attrs,
+	.tfc_tpg_base_attrs		= tcm_loop_tpg_attrs,
+	.tfc_tpg_attrib_attrs		= tcm_loop_tpg_attrib_attrs,
+};
+
+static int __init tcm_loop_fabric_init(void)
+{
+	int ret = -ENOMEM;
+
+	tcm_loop_cmd_cache = kmem_cache_create("tcm_loop_cmd_cache",
+				sizeof(struct tcm_loop_cmd),
+				__alignof__(struct tcm_loop_cmd),
+				0, NULL);
+	if (!tcm_loop_cmd_cache) {
+		pr_debug("kmem_cache_create() for tcm_loop_cmd_cache failed\n");
+		goto out;
+	}
+
+	ret = tcm_loop_alloc_core_bus();
+	if (ret)
+		goto out_destroy_cache;
+
+	ret = target_register_template(&loop_ops);
+	if (ret)
+		goto out_release_core_bus;
+
+	return 0;
+
+out_release_core_bus:
+	tcm_loop_release_core_bus();
+out_destroy_cache:
+	kmem_cache_destroy(tcm_loop_cmd_cache);
+out:
+	return ret;
+}
+
+static void __exit tcm_loop_fabric_exit(void)
+{
+	target_unregister_template(&loop_ops);
+	tcm_loop_release_core_bus();
+	kmem_cache_destroy(tcm_loop_cmd_cache);
+}
+
+MODULE_DESCRIPTION("TCM loopback virtual Linux/SCSI fabric module");
+MODULE_AUTHOR("Nicholas A. Bellinger <nab@risingtidesystems.com>");
+MODULE_LICENSE("GPL");
+module_init(tcm_loop_fabric_init);
+module_exit(tcm_loop_fabric_exit);
diff --git a/drivers/target/loopback/tcm_loop.h b/drivers/target/loopback/tcm_loop.h
new file mode 100644
index 0000000000..437663b390
--- /dev/null
+++ b/drivers/target/loopback/tcm_loop.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/types.h>
+#include <linux/device.h>
+#include <target/target_core_base.h> /* struct se_cmd */
+
+#define TCM_LOOP_VERSION		"v2.1-rc2"
+#define TL_WWN_ADDR_LEN			256
+#define TL_TPGS_PER_HBA			32
+
+struct tcm_loop_cmd {
+	/* State of Linux/SCSI CDB+Data descriptor */
+	u32 sc_cmd_state;
+	/* Tagged command queueing */
+	u32 sc_cmd_tag;
+	/* Pointer to the CDB+Data descriptor from Linux/SCSI subsystem */
+	struct scsi_cmnd *sc;
+	/* The TCM I/O descriptor that is accessed via container_of() */
+	struct se_cmd tl_se_cmd;
+	struct completion tmr_done;
+	/* Sense buffer that will be mapped into outgoing status */
+	unsigned char tl_sense_buf[TRANSPORT_SENSE_BUFFER];
+};
+
+struct tcm_loop_nexus {
+	/*
+	 * Pointer to TCM session for I_T Nexus
+	 */
+	struct se_session *se_sess;
+};
+
+#define TCM_TRANSPORT_ONLINE 0
+#define TCM_TRANSPORT_OFFLINE 1
+
+struct tcm_loop_tpg {
+	unsigned short tl_tpgt;
+	unsigned short tl_transport_status;
+	enum target_prot_type tl_fabric_prot_type;
+	atomic_t tl_tpg_port_count;
+	struct se_portal_group tl_se_tpg;
+	struct tcm_loop_hba *tl_hba;
+	struct tcm_loop_nexus *tl_nexus;
+};
+
+struct tcm_loop_hba {
+	u8 tl_proto_id;
+	unsigned char tl_wwn_address[TL_WWN_ADDR_LEN];
+	struct se_hba_s *se_hba;
+	struct se_lun *tl_hba_lun;
+	struct se_port *tl_hba_lun_sep;
+	struct device dev;
+	struct Scsi_Host *sh;
+	struct tcm_loop_tpg tl_hba_tpgs[TL_TPGS_PER_HBA];
+	struct se_wwn tl_hba_wwn;
+};