[PATCH 4/5] megaraid_sas: scsi-mq support

[Hannes Reinecke <hare@suse.de>]

This patch enables full scsi multiqueue support. But as I have
been seeing performance regressions I've also added a module
parameter 'use_blk_mq', allowing multiqueue to be switched
off if required.

Signed-off-by: Hannes Reinecke <hare@suse.com>
---
 drivers/scsi/megaraid/megaraid_sas_base.c   | 22 +++++++++++++++++
 drivers/scsi/megaraid/megaraid_sas_fusion.c | 38 +++++++++++++++++++++--------
 2 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index d580406..1af47e6 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -48,6 +48,7 @@
 #include <linux/blkdev.h>
 #include <linux/mutex.h>
 #include <linux/poll.h>
+#include <linux/blk-mq-pci.h>
 
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
@@ -104,6 +105,9 @@
 module_param(scmd_timeout, int, S_IRUGO);
 MODULE_PARM_DESC(scmd_timeout, "scsi command timeout (10-90s), default 90s. See megasas_reset_timer.");
 
+bool use_blk_mq = true;
+module_param_named(use_blk_mq, use_blk_mq, bool, 0);
+
 MODULE_LICENSE("GPL");
 MODULE_VERSION(MEGASAS_VERSION);
 MODULE_AUTHOR("megaraidlinux.pdl@avagotech.com");
@@ -1882,6 +1886,17 @@ static void megasas_slave_destroy(struct scsi_device *sdev)
 	sdev->hostdata = NULL;
 }
 
+static int megasas_map_queues(struct Scsi_Host *shost)
+{
+	struct megasas_instance *instance = (struct megasas_instance *)
+		shost->hostdata;
+
+	if (!instance->ctrl_context)
+		return 0;
+
+	return blk_mq_pci_map_queues(&shost->tag_set, instance->pdev, 0);
+}
+
 /*
 * megasas_complete_outstanding_ioctls - Complete outstanding ioctls after a
 *                                       kill adapter
@@ -2986,6 +3001,7 @@ struct device_attribute *megaraid_host_attrs[] = {
 	.slave_configure = megasas_slave_configure,
 	.slave_alloc = megasas_slave_alloc,
 	.slave_destroy = megasas_slave_destroy,
+	.map_queues = megasas_map_queues,
 	.queuecommand = megasas_queue_command,
 	.eh_target_reset_handler = megasas_reset_target,
 	.eh_abort_handler = megasas_task_abort,
@@ -5610,6 +5626,12 @@ static int megasas_io_attach(struct megasas_instance *instance)
 	host->max_id = MEGASAS_MAX_DEV_PER_CHANNEL;
 	host->max_lun = MEGASAS_MAX_LUN;
 	host->max_cmd_len = 16;
+	host->nr_hw_queues = instance->msix_vectors ?
+		instance->msix_vectors : 1;
+	if (use_blk_mq) {
+		host->can_queue = instance->max_scsi_cmds / host->nr_hw_queues;
+		host->use_blk_mq = 1;
+	}
 
 	/*
 	 * Notify the mid-layer about the new controller
diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index eb3cb0f..aba53c0 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -1703,6 +1703,7 @@ static int megasas_create_sg_sense_fusion(struct megasas_instance *instance)
 	struct IO_REQUEST_INFO io_info;
 	struct fusion_context *fusion;
 	struct MR_DRV_RAID_MAP_ALL *local_map_ptr;
+	u16 msix_index;
 	u8 *raidLUN;
 
 	device_id = MEGASAS_DEV_INDEX(scp);
@@ -1792,11 +1793,13 @@ static int megasas_create_sg_sense_fusion(struct megasas_instance *instance)
 			fp_possible = io_info.fpOkForIo;
 	}
 
-	/* Use raw_smp_processor_id() for now until cmd->request->cpu is CPU
-	   id by default, not CPU group id, otherwise all MSI-X queues won't
-	   be utilized */
-	cmd->request_desc->SCSIIO.MSIxIndex = instance->msix_vectors ?
-		raw_smp_processor_id() % instance->msix_vectors : 0;
+	if (shost_use_blk_mq(instance->host)) {
+		u32 blk_tag = blk_mq_unique_tag(scp->request);
+		msix_index = blk_mq_unique_tag_to_hwq(blk_tag);
+	} else
+		msix_index = instance->msix_vectors ?
+			raw_smp_processor_id() % instance->msix_vectors : 0;
+	cmd->request_desc->SCSIIO.MSIxIndex = msix_index;
 
 	if (fp_possible) {
 		megasas_set_pd_lba(io_request, scp->cmd_len, &io_info, scp,
@@ -1971,6 +1974,7 @@ static void megasas_build_ld_nonrw_fusion(struct megasas_instance *instance,
 	struct RAID_CONTEXT	*pRAID_Context;
 	struct MR_PD_CFG_SEQ_NUM_SYNC *pd_sync;
 	struct fusion_context *fusion = instance->ctrl_context;
+	u16 msix_index;
 	pd_sync = (void *)fusion->pd_seq_sync[(instance->pd_seq_map_id - 1) & 1];
 
 	device_id = MEGASAS_DEV_INDEX(scmd);
@@ -2013,11 +2017,14 @@ static void megasas_build_ld_nonrw_fusion(struct megasas_instance *instance,
 		io_request->DevHandle = cpu_to_le16(0xFFFF);
 	}
 
+	if (shost_use_blk_mq(instance->host)) {
+		u32 blk_tag = blk_mq_unique_tag(scmd->request);
+		msix_index = blk_mq_unique_tag_to_hwq(blk_tag);
+	} else
+		msix_index = instance->msix_vectors ?
+			(raw_smp_processor_id() % instance->msix_vectors) : 0;
+	cmd->request_desc->SCSIIO.MSIxIndex = msix_index;
 	cmd->request_desc->SCSIIO.DevHandle = io_request->DevHandle;
-	cmd->request_desc->SCSIIO.MSIxIndex =
-		instance->msix_vectors ?
-		(raw_smp_processor_id() % instance->msix_vectors) : 0;
-
 
 	if (!fp_possible) {
 		/* system pd firmware path */
@@ -2188,7 +2195,18 @@ static void megasas_build_ld_nonrw_fusion(struct megasas_instance *instance,
 		return SCSI_MLQUEUE_DEVICE_BUSY;
 	}
 
-	cmd = megasas_get_cmd_fusion(instance, scmd->request->tag);
+	if (shost_use_blk_mq(instance->host)) {
+		int msix_vectors, hwq_size;
+		u32 blk_tag = blk_mq_unique_tag(scmd->request);
+		u16 hwq = blk_mq_unique_tag_to_hwq(blk_tag);
+		u16 tag = blk_mq_unique_tag_to_tag(blk_tag);
+
+		msix_vectors = instance->msix_vectors ?
+			instance->msix_vectors : 1;
+		hwq_size = instance->max_scsi_cmds / msix_vectors;
+		cmd = megasas_get_cmd_fusion(instance, (hwq * hwq_size) + tag);
+	} else
+		cmd = megasas_get_cmd_fusion(instance, scmd->request->tag);
 
 	index = cmd->index;
 
-- 
1.8.5.6