scsi: mpt3sas: Add module parameter multipath_on_hba

Add module parameter multipath_on_hba to enable/disable multi-port path
topology support.  By default this feature is enabled on SAS3.5 HBA device
and disabled on SAS3 &SAS2.5 HBA devices.

When this feature is disabled then driver uses a default
PhysicalPort(PortID) number i.e. 255 instead of the PhysicalPort number
provided by HBA firmware.

Link: https://lore.kernel.org/r/20201027130847.9962-14-sreekanth.reddy@broadcom.com
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpt3sas_base.h

@@ -1246,6 +1246,7 @@ typedef void (*MPT3SAS_FLUSH_RUNNING_CMDS)(struct MPT3SAS_ADAPTER *ioc);
  *	which ensures the syncrhonization between cli/sysfs_show path.
  * @atomic_desc_capable: Atomic Request Descriptor support.
  * @GET_MSIX_INDEX: Get the msix index of high iops queues.
+ * @multipath_on_hba: flag to determine multipath on hba is enabled or not
  * @port_table_list: list containing HBA's wide/narrow port's info
  */
 struct MPT3SAS_ADAPTER {
@@ -1540,6 +1541,7 @@ struct MPT3SAS_ADAPTER {
 	PUT_SMID_DEFAULT put_smid_default;
 	GET_MSIX_INDEX get_msix_index_for_smlio;
 
+	u8		multipath_on_hba;
 	struct list_head port_table_list;
 };
 

drivers/scsi/mpt3sas/mpt3sas_ctl.c

@@ -902,8 +902,10 @@ _ctl_do_mpt_command(struct MPT3SAS_ADAPTER *ioc, struct mpt3_ioctl_command karg,
 		    (Mpi2SmpPassthroughRequest_t *)mpi_request;
 		u8 *data;
 
-		/* ioc determines which port to use */
+		if (!ioc->multipath_on_hba) {
-		smp_request->PhysicalPort = 0xFF;
+			/* ioc determines which port to use */
+			smp_request->PhysicalPort = 0xFF;
+		}
 		if (smp_request->PassthroughFlags &
 		    MPI2_SMP_PT_REQ_PT_FLAGS_IMMEDIATE)
 			data = (u8 *)&smp_request->SGL;

drivers/scsi/mpt3sas/mpt3sas_scsih.c

@@ -159,6 +159,15 @@ module_param(enable_sdev_max_qd, bool, 0444);
 MODULE_PARM_DESC(enable_sdev_max_qd,
 	"Enable sdev max qd as can_queue, def=disabled(0)");
 
+static int multipath_on_hba = -1;
+module_param(multipath_on_hba, int, 0);
+MODULE_PARM_DESC(multipath_on_hba,
+	"Multipath support to add same target device\n\t\t"
+	"as many times as it is visible to HBA from various paths\n\t\t"
+	"(by default:\n\t\t"
+	"\t SAS 2.0 & SAS 3.0 HBA - This will be disabled,\n\t\t"
+	"\t SAS 3.5 HBA - This will be enabled)");
+
 /* raid transport support */
 static struct raid_template *mpt3sas_raid_template;
 static struct raid_template *mpt2sas_raid_template;
@@ -373,6 +382,14 @@ mpt3sas_get_port_by_id(struct MPT3SAS_ADAPTER *ioc,
 {
 	struct hba_port *port, *port_next;
 
+	/*
+	 * When multipath_on_hba is disabled then
+	 * search the hba_port entry using default
+	 * port id i.e. 255
+	 */
+	if (!ioc->multipath_on_hba)
+		port_id = MULTIPATH_DISABLED_PORT_ID;
+
 	list_for_each_entry_safe(port, port_next,
 	    &ioc->port_table_list, list) {
 		if (port->port_id != port_id)
@@ -384,6 +401,24 @@ mpt3sas_get_port_by_id(struct MPT3SAS_ADAPTER *ioc,
 		return port;
 	}
 
+	/*
+	 * Allocate hba_port object for default port id (i.e. 255)
+	 * when multipath_on_hba is disabled for the HBA.
+	 * And add this object to port_table_list.
+	 */
+	if (!ioc->multipath_on_hba) {
+		port = kzalloc(sizeof(struct hba_port), GFP_KERNEL);
+		if (!port)
+			return NULL;
+
+		port->port_id = port_id;
+		ioc_info(ioc,
+		   "hba_port entry: %p, port: %d is added to hba_port list\n",
+		   port, port->port_id);
+		list_add_tail(&port->list,
+		    &ioc->port_table_list);
+		return port;
+	}
 	return NULL;
 }
 
@@ -10014,6 +10049,7 @@ _scsih_search_responding_expanders(struct MPT3SAS_ADAPTER *ioc)
 	u16 ioc_status;
 	u64 sas_address;
 	u16 handle;
+	u8 port;
 
 	ioc_info(ioc, "search for expanders: start\n");
 
@@ -10031,10 +10067,12 @@ _scsih_search_responding_expanders(struct MPT3SAS_ADAPTER *ioc)
 
 		handle = le16_to_cpu(expander_pg0.DevHandle);
 		sas_address = le64_to_cpu(expander_pg0.SASAddress);
+		port = expander_pg0.PhysicalPort;
 		pr_info(
 		    "\texpander present: handle(0x%04x), sas_addr(0x%016llx), port:%d\n",
 		    handle, (unsigned long long)sas_address,
-		    expander_pg0.PhysicalPort);
+		    (ioc->multipath_on_hba ?
+		    port : MULTIPATH_DISABLED_PORT_ID));
 		_scsih_mark_responding_expander(ioc, &expander_pg0);
 	}
 
@@ -10477,8 +10515,10 @@ mpt3sas_scsih_reset_done_handler(struct MPT3SAS_ADAPTER *ioc)
 	dtmprintk(ioc, ioc_info(ioc, "%s: MPT3_IOC_DONE_RESET\n", __func__));
 	if ((!ioc->is_driver_loading) && !(disable_discovery > 0 &&
 					   !ioc->sas_hba.num_phys)) {
-		_scsih_sas_port_refresh(ioc);
+		if (ioc->multipath_on_hba) {
-		_scsih_update_vphys_after_reset(ioc);
+			_scsih_sas_port_refresh(ioc);
+			_scsih_update_vphys_after_reset(ioc);
+		}
 		_scsih_prep_device_scan(ioc);
 		_scsih_create_enclosure_list_after_reset(ioc);
 		_scsih_search_responding_sas_devices(ioc);
@@ -11766,6 +11806,12 @@ _scsih_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 			ioc->mfg_pg10_hide_flag = MFG_PAGE10_EXPOSE_ALL_DISKS;
 			break;
 		}
+
+		if (multipath_on_hba == -1 || multipath_on_hba == 0)
+			ioc->multipath_on_hba = 0;
+		else
+			ioc->multipath_on_hba = 1;
+
 		break;
 	case MPI25_VERSION:
 	case MPI26_VERSION:
@@ -11827,6 +11873,23 @@ _scsih_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 				ioc->combined_reply_index_count =
 				 MPT3_SUP_REPLY_POST_HOST_INDEX_REG_COUNT_G3;
 		}
+
+		switch (ioc->is_gen35_ioc) {
+		case 0:
+			if (multipath_on_hba == -1 || multipath_on_hba == 0)
+				ioc->multipath_on_hba = 0;
+			else
+				ioc->multipath_on_hba = 1;
+			break;
+		case 1:
+			if (multipath_on_hba == -1 || multipath_on_hba > 0)
+				ioc->multipath_on_hba = 1;
+			else
+				ioc->multipath_on_hba = 0;
+		default:
+			break;
+		}
+
 		break;
 	default:
 		return -ENODEV;

drivers/scsi/mpt3sas/mpt3sas_transport.c

@@ -912,7 +912,8 @@ mpt3sas_transport_port_remove(struct MPT3SAS_ADAPTER *ioc, u64 sas_address,
 		return;
 	}
 
-	if (sas_node->handle <= ioc->sas_hba.num_phys) {
+	if (sas_node->handle <= ioc->sas_hba.num_phys &&
+	    (ioc->multipath_on_hba)) {
 		if (port->vphys_mask) {
 			list_for_each_entry_safe(vphy, vphy_next,
 			    &port->vphys_list, list) {
@@ -1172,7 +1173,8 @@ mpt3sas_transport_update_links(struct MPT3SAS_ADAPTER *ioc,
 	if (handle && (link_rate >= MPI2_SAS_NEG_LINK_RATE_1_5)) {
 		_transport_set_identify(ioc, handle,
 		    &mpt3sas_phy->remote_identify);
-		if (sas_node->handle <= ioc->sas_hba.num_phys) {
+		if ((sas_node->handle <= ioc->sas_hba.num_phys) &&
+		    (ioc->multipath_on_hba)) {
 			list_for_each_entry(hba_port,
 			    &ioc->port_table_list, list) {
 				if (hba_port->sas_address == sas_address &&