scsi: mpt3sas: Add io_uring iopoll support

Enable the driver to work in non-IRQ mode, i.e. there will not be any MSI-X
vectors associated with queues dedicated to polling. The IOC hardware is
single submission queue and multiple reply queue. However, using the shared
host tagset support it is possible to simulate multiple hardware queues.

When poll_queues are enabled through the module parameter, the driver will
allocate extra reply queues without an MSI-X association. All I/O
completion on these queues will be done through the iopoll interface.

Link: https://lore.kernel.org/r/20210727081212.2742-1-sreekanth.reddy@broadcom.com
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 52 insertions, 10 deletions

diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index 866d118f7931..f15c809e22c1 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -11178,8 +11178,10 @@ static void scsih_remove(struct pci_dev *pdev)
 
 	ioc->remove_host = 1;
 
-	if (!pci_device_is_present(pdev))
+	if (!pci_device_is_present(pdev)) {
+		mpt3sas_base_pause_mq_polling(ioc);
 		_scsih_flush_running_cmds(ioc);
+	}
 
 	_scsih_fw_event_cleanup_queue(ioc);
 
@@ -11274,8 +11276,10 @@ scsih_shutdown(struct pci_dev *pdev)
 
 	ioc->remove_host = 1;
 
-	if (!pci_device_is_present(pdev))
+	if (!pci_device_is_present(pdev)) {
+		mpt3sas_base_pause_mq_polling(ioc);
 		_scsih_flush_running_cmds(ioc);
+	}
 
 	_scsih_fw_event_cleanup_queue(ioc);
 
@@ -11780,12 +11784,41 @@ static int scsih_map_queues(struct Scsi_Host *shost)
 {
 	struct MPT3SAS_ADAPTER *ioc =
 	    (struct MPT3SAS_ADAPTER *)shost->hostdata;
+	struct blk_mq_queue_map *map;
+	int i, qoff, offset;
+	int nr_msix_vectors = ioc->iopoll_q_start_index;
+	int iopoll_q_count = ioc->reply_queue_count - nr_msix_vectors;
 
-	if (ioc->shost->nr_hw_queues == 1)
+	if (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);
+	for (i = 0, qoff = 0; i < shost->nr_maps; i++) {
+		map = &shost->tag_set.map[i];
+		map->nr_queues = 0;
+		offset = 0;
+		if (i == HCTX_TYPE_DEFAULT) {
+			map->nr_queues =
+			    nr_msix_vectors - ioc->high_iops_queues;
+			offset = ioc->high_iops_queues;
+		} else if (i == HCTX_TYPE_POLL)
+			map->nr_queues = iopoll_q_count;
+
+		if (!map->nr_queues)
+			BUG_ON(i == HCTX_TYPE_DEFAULT);
+
+		/*
+		 * The poll queue(s) doesn't have an IRQ (and hence IRQ
+		 * affinity), so use the regular blk-mq cpu mapping
+		 */
+		map->queue_offset = qoff;
+		if (i != HCTX_TYPE_POLL)
+			blk_mq_pci_map_queues(map, ioc->pdev, offset);
+		else
+			blk_mq_map_queues(map);
+
+		qoff += map->nr_queues;
+	}
+	return 0;
 }
 
 /* shost template for SAS 2.0 HBA devices */
@@ -11856,6 +11889,7 @@ static struct scsi_host_template mpt3sas_driver_template = {
 	.track_queue_depth		= 1,
 	.cmd_size			= sizeof(struct scsiio_tracker),
 	.map_queues			= scsih_map_queues,
+	.mq_poll			= mpt3sas_blk_mq_poll,
 };
 
 /* raid transport support for SAS 3.0 HBA devices */
@@ -11952,6 +11986,7 @@ _scsih_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	struct Scsi_Host *shost = NULL;
 	int rv;
 	u16 hba_mpi_version;
+	int iopoll_q_count = 0;
 
 	/* Determine in which MPI version class this pci device belongs */
 	hba_mpi_version = _scsih_determine_hba_mpi_version(pdev);
@@ -12199,6 +12234,11 @@ _scsih_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto out_thread_fail;
 	}
 
+	shost->host_tagset = 0;
+
+	if (ioc->is_gen35_ioc && host_tagset_enable)
+		shost->host_tagset = 1;
+
 	ioc->is_driver_loading = 1;
 	if ((mpt3sas_base_attach(ioc))) {
 		ioc_err(ioc, "failure at %s:%d/%s()!\n",
@@ -12221,16 +12261,17 @@ _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;
+	if (shost->host_tagset) {
 		shost->nr_hw_queues =
 		    ioc->reply_queue_count - ioc->high_iops_queues;
 
+		iopoll_q_count =
+		    ioc->reply_queue_count - ioc->iopoll_q_start_index;
+
+		shost->nr_maps = iopoll_q_count ? 3 : 1;
+
 		dev_info(&ioc->pdev->dev,
 		    "Max SCSIIO MPT commands: %d shared with nr_hw_queues = %d\n",
 		    shost->can_queue, shost->nr_hw_queues);
@@ -12354,6 +12395,7 @@ scsih_pci_error_detected(struct pci_dev *pdev, pci_channel_state_t state)
 		/* Permanent error, prepare for device removal */
 		ioc->pci_error_recovery = 1;
 		mpt3sas_base_stop_watchdog(ioc);
+		mpt3sas_base_pause_mq_polling(ioc);
 		_scsih_flush_running_cmds(ioc);
 		return PCI_ERS_RESULT_DISCONNECT;
 	}