scsi: mpt3sas: Add support for shared host tagset for CPU hotplug

MPT Fusion adapters can steer completions to individual queues and we now
have support for shared host-wide tags in the I/O stack. The addition of
the host-wide tags allows us to enable multiqueue support for MPT Fusion
adapters. Once host-wise tags are enabled, the CPU hotplug feature is also
supported.

Allow use of host-wide tags to be disabled through the "host_tagset_enable"
module parameter. Once we do not have any major performance regressions
using host-wide tags, we will drop the hand-crafted interrupt affinity
settings.

Performance is meeting expectations. About 3.1M IOPS using 24 Drive SSD on
Aero controllers.

Link: https://lore.kernel.org/r/20210202095832.23072-1-sreekanth.reddy@broadcom.com
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 41 insertions, 1 deletions

diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index c8b09a81834d..a665d1c93061 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -54,6 +54,7 @@
 #include <linux/interrupt.h>
 #include <linux/aer.h>
 #include <linux/raid_class.h>
+#include <linux/blk-mq-pci.h>
 #include <asm/unaligned.h>
 
 #include "mpt3sas_base.h"
@@ -168,6 +169,11 @@ MODULE_PARM_DESC(multipath_on_hba,
 	"\t SAS 2.0 & SAS 3.0 HBA - This will be disabled,\n\t\t"
 	"\t SAS 3.5 HBA - This will be enabled)");
 
+static int host_tagset_enable = 1;
+module_param(host_tagset_enable, int, 0444);
+MODULE_PARM_DESC(host_tagset_enable,
+	"Shared host tagset enable/disable Default: enable(1)");
+
 /* raid transport support */
 static struct raid_template *mpt3sas_raid_template;
 static struct raid_template *mpt2sas_raid_template;
@@ -1743,10 +1749,12 @@ mpt3sas_scsih_scsi_lookup_get(struct MPT3SAS_ADAPTER *ioc, u16 smid)
 	struct scsi_cmnd *scmd = NULL;
 	struct scsiio_tracker *st;
 	Mpi25SCSIIORequest_t *mpi_request;
+	u16 tag = smid - 1;
 
 	if (smid > 0  &&
 	    smid <= ioc->scsiio_depth - INTERNAL_SCSIIO_CMDS_COUNT) {
-		u32 unique_tag = smid - 1;
+		u32 unique_tag =
+		    ioc->io_queue_num[tag] << BLK_MQ_UNIQUE_TAG_BITS | tag;
 
 		mpi_request = mpt3sas_base_get_msg_frame(ioc, smid);
 
@@ -11599,6 +11607,22 @@ scsih_scan_finished(struct Scsi_Host *shost, unsigned long time)
 	return 1;
 }
 
+/**
+ * scsih_map_queues - map reply queues with request queues
+ * @shost: SCSI host pointer
+ */
+static int scsih_map_queues(struct Scsi_Host *shost)
+{
+	struct MPT3SAS_ADAPTER *ioc =
+	    (struct MPT3SAS_ADAPTER *)shost->hostdata;
+
+	if (ioc->shost->nr_hw_queues == 1)
+		return 0;
+
+	return blk_mq_pci_map_queues(&shost->tag_set.map[HCTX_TYPE_DEFAULT],
+	    ioc->pdev, ioc->high_iops_queues);
+}
+
 /* shost template for SAS 2.0 HBA devices */
 static struct scsi_host_template mpt2sas_driver_template = {
 	.module				= THIS_MODULE,
@@ -11666,6 +11690,7 @@ static struct scsi_host_template mpt3sas_driver_template = {
 	.sdev_attrs			= mpt3sas_dev_attrs,
 	.track_queue_depth		= 1,
 	.cmd_size			= sizeof(struct scsiio_tracker),
+	.map_queues			= scsih_map_queues,
 };
 
 /* raid transport support for SAS 3.0 HBA devices */
@@ -12028,6 +12053,21 @@ _scsih_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	} else
 		ioc->hide_drives = 0;
 
+	shost->host_tagset = 0;
+	shost->nr_hw_queues = 1;
+
+	if (ioc->is_gen35_ioc && ioc->reply_queue_count > 1 &&
+	    host_tagset_enable && ioc->smp_affinity_enable) {
+
+		shost->host_tagset = 1;
+		shost->nr_hw_queues =
+		    ioc->reply_queue_count - ioc->high_iops_queues;
+
+		dev_info(&ioc->pdev->dev,
+		    "Max SCSIIO MPT commands: %d shared with nr_hw_queues = %d\n",
+		    shost->can_queue, shost->nr_hw_queues);
+	}
+
 	rv = scsi_add_host(shost, &pdev->dev);
 	if (rv) {
 		ioc_err(ioc, "failure at %s:%d/%s()!\n",