[RFC PATCH v2 1/1] scsi: mpi3mr: Introduce smp_affinity_enable module parameter

[Aaron Tomlin <atomlin@atomlin.com>]

This patch introduces a new module parameter namely
"smp_affinity_enable", to govern the application of system-wide IRQ
affinity (with kernel boot-time parameter "irqaffinity") for MSI-X
interrupts. By default, the default IRQ affinity mask will not be
respected. Set smp_affinity_enable to 0 disables this behaviour.
Consequently, preventing the auto-assignment of MSI-X IRQs.

Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
---
 drivers/scsi/mpi3mr/mpi3mr.h    |  1 +
 drivers/scsi/mpi3mr/mpi3mr_fw.c | 14 ++++++++++++--
 drivers/scsi/mpi3mr/mpi3mr_os.c | 14 +++++++++++---
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/mpi3mr/mpi3mr.h b/drivers/scsi/mpi3mr/mpi3mr.h
index 9bbc7cb98ca3..82a0c1dd2f59 100644
--- a/drivers/scsi/mpi3mr/mpi3mr.h
+++ b/drivers/scsi/mpi3mr/mpi3mr.h
@@ -1378,6 +1378,7 @@ struct mpi3mr_ioc {
 	u32 num_tb_segs;
 	struct dma_pool *trace_buf_pool;
 	struct segments *trace_buf;
+	bool smp_affinity_enable;
 
 };
 
diff --git a/drivers/scsi/mpi3mr/mpi3mr_fw.c b/drivers/scsi/mpi3mr/mpi3mr_fw.c
index 1d7901a8f0e4..9cbe1744213d 100644
--- a/drivers/scsi/mpi3mr/mpi3mr_fw.c
+++ b/drivers/scsi/mpi3mr/mpi3mr_fw.c
@@ -22,6 +22,10 @@ static int poll_queues;
 module_param(poll_queues, int, 0444);
 MODULE_PARM_DESC(poll_queues, "Number of queues for io_uring poll mode. (Range 1 - 126)");
 
+static int smp_affinity_enable = 1;
+module_param(smp_affinity_enable, int, 0444);
+MODULE_PARM_DESC(smp_affinity_enable, "SMP affinity feature enable/disable Default: enable(1)");
+
 #if defined(writeq) && defined(CONFIG_64BIT)
 static inline void mpi3mr_writeq(__u64 b, volatile void __iomem *addr)
 {
@@ -821,6 +825,7 @@ static int mpi3mr_setup_isr(struct mpi3mr_ioc *mrioc, u8 setup_one)
 	int retval;
 	int i;
 	struct irq_affinity desc = { .pre_vectors =  1, .post_vectors = 1 };
+	struct irq_affinity *descp = &desc;
 
 	if (mrioc->is_intr_info_set)
 		return 0;
@@ -852,10 +857,13 @@ static int mpi3mr_setup_isr(struct mpi3mr_ioc *mrioc, u8 setup_one)
 
 		desc.post_vectors = mrioc->requested_poll_qcount;
 		min_vec = desc.pre_vectors + desc.post_vectors;
-		irq_flags |= PCI_IRQ_AFFINITY | PCI_IRQ_ALL_TYPES;
+		if (mrioc->smp_affinity_enable)
+			irq_flags |= PCI_IRQ_AFFINITY | PCI_IRQ_ALL_TYPES;
+		else
+			descp = NULL;
 
 		retval = pci_alloc_irq_vectors_affinity(mrioc->pdev,
-			min_vec, max_vectors, irq_flags, &desc);
+			min_vec, max_vectors, irq_flags, descp);
 
 		if (retval < 0) {
 			ioc_err(mrioc, "cannot allocate irq vectors, ret %d\n",
@@ -4233,6 +4241,8 @@ int mpi3mr_init_ioc(struct mpi3mr_ioc *mrioc)
 		goto out_failed_noretry;
 	}
 
+	mrioc->smp_affinity_enable = smp_affinity_enable ? true : false;
+
 	retval = mpi3mr_setup_isr(mrioc, 1);
 	if (retval) {
 		ioc_err(mrioc, "Failed to setup ISR error %d\n",
diff --git a/drivers/scsi/mpi3mr/mpi3mr_os.c b/drivers/scsi/mpi3mr/mpi3mr_os.c
index ce444efd859e..6ea73cf7579b 100644
--- a/drivers/scsi/mpi3mr/mpi3mr_os.c
+++ b/drivers/scsi/mpi3mr/mpi3mr_os.c
@@ -4064,6 +4064,9 @@ static void mpi3mr_map_queues(struct Scsi_Host *shost)
 	int i, qoff, offset;
 	struct blk_mq_queue_map *map = NULL;
 
+	if (shost->nr_hw_queues == 1)
+		return;
+
 	offset = mrioc->op_reply_q_offset;
 
 	for (i = 0, qoff = 0; i < HCTX_MAX_TYPES; i++) {
@@ -5422,8 +5425,6 @@ mpi3mr_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	shost->max_channel = 0;
 	shost->max_id = 0xFFFFFFFF;
 
-	shost->host_tagset = 1;
-
 	if (prot_mask >= 0)
 		scsi_host_set_prot(shost, prot_mask);
 	else {
@@ -5471,7 +5472,14 @@ mpi3mr_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto init_ioc_failed;
 	}
 
-	shost->nr_hw_queues = mrioc->num_op_reply_q;
+	shost->host_tagset = 0;
+	shost->nr_hw_queues = 1;
+
+	if (mrioc->smp_affinity_enable) {
+		shost->nr_hw_queues = mrioc->num_op_reply_q;
+		shost->host_tagset = 1;
+	}
+
 	if (mrioc->active_poll_qcount)
 		shost->nr_maps = 3;
 
-- 
2.49.0