IB/iser: Introduce pi_enable, pi_guard module parameters

Use modparams to activate protection information support.

pi_enable bool: Based on this parameter iSER will know if it should
support T10-PI.  We don't want to do this by default as it requires to
allocate and initialize extra resources.  In case pi_enable=N, iSER
won't publish to SCSI midlayer any DIF capabilities.

pi_guard int: Based on this parameter iSER will publish DIX guard type
support to SCSI midlayer.  0 means CRC is allowed to be passed in DIX
buffers, 1 (or non-zero) means IP-CSUM is allowed to be passed in DIX
buffers.  Note that over the wire, only CRC is allowed.

In the next phase, it is worth considering passing these parameters
from iscsid via nlmsg.  This will allow these parameters to be
connection based rather than global.
Signed-off-by: NAlex Tabachnik <alext@mellanox.com>
Signed-off-by: NSagi Grimberg <sagig@mellanox.com>
Signed-off-by: NRoland Dreier <roland@purestorage.com>

drivers/infiniband/ulp/iser/iscsi_iser.c

@@ -82,6 +82,8 @@ static unsigned int iscsi_max_lun = 512;
 module_param_named(max_lun, iscsi_max_lun, uint, S_IRUGO);
 
 int iser_debug_level = 0;
+bool iser_pi_enable = false;
+int iser_pi_guard = 0;
 
 MODULE_DESCRIPTION("iSER (iSCSI Extensions for RDMA) Datamover");
 MODULE_LICENSE("Dual BSD/GPL");
@@ -91,6 +93,12 @@ MODULE_VERSION(DRV_VER);
 module_param_named(debug_level, iser_debug_level, int, 0644);
 MODULE_PARM_DESC(debug_level, "Enable debug tracing if > 0 (default:disabled)");
 
+module_param_named(pi_enable, iser_pi_enable, bool, 0644);
+MODULE_PARM_DESC(pi_enable, "Enable T10-PI offload support (default:disabled)");
+
+module_param_named(pi_guard, iser_pi_guard, int, 0644);
+MODULE_PARM_DESC(pi_guard, "T10-PI guard_type, 0:CRC|1:IP_CSUM (default:CRC)");
+
 struct iser_global ig;
 
 void

drivers/infiniband/ulp/iser/iscsi_iser.h

@@ -317,6 +317,7 @@ struct iser_conn {
 	unsigned int 		     rx_desc_head;
 	struct iser_rx_desc	     *rx_descs;
 	struct ib_recv_wr	     rx_wr[ISER_MIN_POSTED_RX];
+	bool			     pi_support;
 
 	/* Connection memory registration pool */
 	union {
@@ -371,6 +372,8 @@ struct iser_global {
 
 extern struct iser_global ig;
 extern int iser_debug_level;
+extern bool iser_pi_enable;
+extern int iser_pi_guard;
 
 /* allocate connection resources needed for rdma functionality */
 int iser_conn_set_full_featured_mode(struct iscsi_conn *conn);

drivers/infiniband/ulp/iser/iser_verbs.c

@@ -607,6 +607,19 @@ static int iser_addr_handler(struct rdma_cm_id *cma_id)
 	ib_conn = (struct iser_conn *)cma_id->context;
 	ib_conn->device = device;
 
+	/* connection T10-PI support */
+	if (iser_pi_enable) {
+		if (!(device->dev_attr.device_cap_flags &
+		      IB_DEVICE_SIGNATURE_HANDOVER)) {
+			iser_warn("T10-PI requested but not supported on %s, "
+				  "continue without T10-PI\n",
+				  ib_conn->device->ib_device->name);
+			ib_conn->pi_support = false;
+		} else {
+			ib_conn->pi_support = true;
+		}
+	}
+
 	ret = rdma_resolve_route(cma_id, 1000);
 	if (ret) {
 		iser_err("resolve route failed: %d\n", ret);