scsi: ibmvfc: Implement channel enquiry and setup commands

New NPIV_ENQUIRY_CHANNEL and NPIV_SETUP_CHANNEL management datagrams (MADs)
were defined in a previous patchset. If the client advertises a desire to
use channels and the partner VIOS is channel capable then the client must
proceed with channel enquiry to determine the maximum number of channels
the VIOS is capable of providing, and registering SubCRQs via channel setup
with the VIOS immediately following NPIV Login. This handshaking should not
be performed for subsequent NPIV Logins unless the CRQ connection has been
reset.

Implement these two new MADs and issue them following a successful NPIV
login where the VIOS has set the SUPPORT_CHANNELS capability bit in the
NPIV Login response.

Link: https://lore.kernel.org/r/20210114203148.246656-13-tyreld@linux.ibm.com
Reviewed-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ibmvscsi/ibmvfc.c

@@ -909,6 +909,8 @@ static int ibmvfc_reset_crq(struct ibmvfc_host *vhost)
 	spin_lock(vhost->crq.q_lock);
 	vhost->state = IBMVFC_NO_CRQ;
 	vhost->logged_in = 0;
+	vhost->do_enquiry = 1;
+	vhost->using_channels = 0;
 
 	/* Clean out the queue */
 	memset(crq->msgs.crq, 0, PAGE_SIZE);
@@ -4586,6 +4588,118 @@ static void ibmvfc_discover_targets(struct ibmvfc_host *vhost)
 		ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
 }
 
+static void ibmvfc_channel_setup_done(struct ibmvfc_event *evt)
+{
+	struct ibmvfc_host *vhost = evt->vhost;
+	u32 mad_status = be16_to_cpu(evt->xfer_iu->channel_setup.common.status);
+	int level = IBMVFC_DEFAULT_LOG_LEVEL;
+
+	ibmvfc_free_event(evt);
+
+	switch (mad_status) {
+	case IBMVFC_MAD_SUCCESS:
+		ibmvfc_dbg(vhost, "Channel Setup succeded\n");
+		vhost->do_enquiry = 0;
+		break;
+	case IBMVFC_MAD_FAILED:
+		level += ibmvfc_retry_host_init(vhost);
+		ibmvfc_log(vhost, level, "Channel Setup failed\n");
+		fallthrough;
+	case IBMVFC_MAD_DRIVER_FAILED:
+		return;
+	default:
+		dev_err(vhost->dev, "Invalid Channel Setup response: 0x%x\n",
+			mad_status);
+		ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
+		return;
+	}
+
+	ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_QUERY);
+	wake_up(&vhost->work_wait_q);
+}
+
+static void ibmvfc_channel_setup(struct ibmvfc_host *vhost)
+{
+	struct ibmvfc_channel_setup_mad *mad;
+	struct ibmvfc_channel_setup *setup_buf = vhost->channel_setup_buf;
+	struct ibmvfc_event *evt = ibmvfc_get_event(&vhost->crq);
+
+	memset(setup_buf, 0, sizeof(*setup_buf));
+	setup_buf->flags = cpu_to_be32(IBMVFC_CANCEL_CHANNELS);
+
+	ibmvfc_init_event(evt, ibmvfc_channel_setup_done, IBMVFC_MAD_FORMAT);
+	mad = &evt->iu.channel_setup;
+	memset(mad, 0, sizeof(*mad));
+	mad->common.version = cpu_to_be32(1);
+	mad->common.opcode = cpu_to_be32(IBMVFC_CHANNEL_SETUP);
+	mad->common.length = cpu_to_be16(sizeof(*mad));
+	mad->buffer.va = cpu_to_be64(vhost->channel_setup_dma);
+	mad->buffer.len = cpu_to_be32(sizeof(*vhost->channel_setup_buf));
+
+	ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_INIT_WAIT);
+
+	if (!ibmvfc_send_event(evt, vhost, default_timeout))
+		ibmvfc_dbg(vhost, "Sent channel setup\n");
+	else
+		ibmvfc_link_down(vhost, IBMVFC_LINK_DOWN);
+}
+
+static void ibmvfc_channel_enquiry_done(struct ibmvfc_event *evt)
+{
+	struct ibmvfc_host *vhost = evt->vhost;
+	struct ibmvfc_channel_enquiry *rsp = &evt->xfer_iu->channel_enquiry;
+	u32 mad_status = be16_to_cpu(rsp->common.status);
+	int level = IBMVFC_DEFAULT_LOG_LEVEL;
+
+	switch (mad_status) {
+	case IBMVFC_MAD_SUCCESS:
+		ibmvfc_dbg(vhost, "Channel Enquiry succeeded\n");
+		vhost->max_vios_scsi_channels = be32_to_cpu(rsp->num_scsi_subq_channels);
+		ibmvfc_free_event(evt);
+		break;
+	case IBMVFC_MAD_FAILED:
+		level += ibmvfc_retry_host_init(vhost);
+		ibmvfc_log(vhost, level, "Channel Enquiry failed\n");
+		fallthrough;
+	case IBMVFC_MAD_DRIVER_FAILED:
+		ibmvfc_free_event(evt);
+		return;
+	default:
+		dev_err(vhost->dev, "Invalid Channel Enquiry response: 0x%x\n",
+			mad_status);
+		ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
+		ibmvfc_free_event(evt);
+		return;
+	}
+
+	ibmvfc_channel_setup(vhost);
+}
+
+static void ibmvfc_channel_enquiry(struct ibmvfc_host *vhost)
+{
+	struct ibmvfc_channel_enquiry *mad;
+	struct ibmvfc_event *evt = ibmvfc_get_event(&vhost->crq);
+
+	ibmvfc_init_event(evt, ibmvfc_channel_enquiry_done, IBMVFC_MAD_FORMAT);
+	mad = &evt->iu.channel_enquiry;
+	memset(mad, 0, sizeof(*mad));
+	mad->common.version = cpu_to_be32(1);
+	mad->common.opcode = cpu_to_be32(IBMVFC_CHANNEL_ENQUIRY);
+	mad->common.length = cpu_to_be16(sizeof(*mad));
+
+	if (IBMVFC_MIG_NO_SUB_TO_CRQ)
+		mad->flags |= cpu_to_be32(IBMVFC_NO_CHANNELS_TO_CRQ_SUPPORT);
+	if (IBMVFC_MIG_NO_N_TO_M)
+		mad->flags |= cpu_to_be32(IBMVFC_NO_N_TO_M_CHANNELS_SUPPORT);
+
+	ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_INIT_WAIT);
+
+	if (!ibmvfc_send_event(evt, vhost, default_timeout))
+		ibmvfc_dbg(vhost, "Send channel enquiry\n");
+	else
+		ibmvfc_link_down(vhost, IBMVFC_LINK_DEAD);
+}
+
 /**
  * ibmvfc_npiv_login_done - Completion handler for NPIV Login
  * @evt:	ibmvfc event struct
@@ -4667,8 +4781,14 @@ static void ibmvfc_npiv_login_done(struct ibmvfc_event *evt)
 
 	vhost->host->can_queue = be32_to_cpu(rsp->max_cmds) - IBMVFC_NUM_INTERNAL_REQ;
 	vhost->host->max_sectors = npiv_max_sectors;
-	ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_QUERY);
-	wake_up(&vhost->work_wait_q);
+
+	if (ibmvfc_check_caps(vhost, IBMVFC_CAN_SUPPORT_CHANNELS) && vhost->do_enquiry) {
+		ibmvfc_channel_enquiry(vhost);
+	} else {
+		vhost->do_enquiry = 0;
+		ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_QUERY);
+		wake_up(&vhost->work_wait_q);
+	}
 }
 
 /**
@@ -5477,9 +5597,20 @@ static int ibmvfc_alloc_mem(struct ibmvfc_host *vhost)
 		goto free_trace;
 	}
 
+	vhost->channel_setup_buf = dma_alloc_coherent(dev, sizeof(*vhost->channel_setup_buf),
+						      &vhost->channel_setup_dma,
+						      GFP_KERNEL);
+
+	if (!vhost->channel_setup_buf) {
+		dev_err(dev, "Couldn't allocate Channel Setup buffer\n");
+		goto free_tgt_pool;
+	}
+
 	LEAVE;
 	return 0;
 
+free_tgt_pool:
+	mempool_destroy(vhost->tgt_pool);
 free_trace:
 	kfree(vhost->trace);
 free_disc_buffer:

drivers/scsi/ibmvscsi/ibmvfc.h

@@ -854,10 +854,13 @@ struct ibmvfc_host {
 	struct ibmvfc_npiv_login login_info;
 	union ibmvfc_npiv_login_data *login_buf;
 	dma_addr_t login_buf_dma;
+	struct ibmvfc_channel_setup *channel_setup_buf;
+	dma_addr_t channel_setup_dma;
 	int disc_buf_sz;
 	int log_level;
 	struct ibmvfc_discover_targets_entry *disc_buf;
 	struct mutex passthru_mutex;
+	int max_vios_scsi_channels;
 	int task_set;
 	int init_retries;
 	int discovery_threads;