scsi: smartpqi: Add module param to disable managed ints

Allow SMP affinity to be changeable by disabling managed interrupts.

On distributions where the driver is enabled for multi-queue support the
driver utilizes kernel managed interrupts, which automatically distributes
interrupts to all available CPUs and assigns SMP affinity.

On most distributions, the affinity can not be changed by the user.

This change will allow managed interrupts to be disabled by the user via a
module parameter while still allowing multi-queue support to function
properly.

Use the module parameter disable_managed_interrupts=1

Link: https://lore.kernel.org/r/165730606638.177165.12846020942931640329.stgit@brunhilda
Reviewed-by: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microchip.com>
Signed-off-by: Mike McGowen <Mike.McGowen@microchip.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: mchp-memcgowen

drivers/scsi/smartpqi/smartpqi.h

@@ -1351,7 +1351,7 @@ struct pqi_ctrl_info {
 	u8		enable_r6_writes : 1;
 	u8		lv_drive_type_mix_valid : 1;
 	u8		enable_stream_detection : 1;
-
+	u8		disable_managed_interrupts : 1;
 	u8		ciss_report_log_flags;
 	u32		max_transfer_encrypted_sas_sata;
 	u32		max_transfer_encrypted_nvme;

drivers/scsi/smartpqi/smartpqi_init.c

@@ -175,6 +175,12 @@ module_param_named(hide_vsep,
 	pqi_hide_vsep, int, 0644);
 MODULE_PARM_DESC(hide_vsep, "Hide the virtual SEP for direct attached drives.");
 
+static int pqi_disable_managed_interrupts;
+module_param_named(disable_managed_interrupts,
+	pqi_disable_managed_interrupts, int, 0644);
+MODULE_PARM_DESC(disable_managed_interrupts,
+	"Disable the kernel automatically assigning SMP affinity to IRQs.");
+
 static char *raid_levels[] = {
 	"RAID-0",
 	"RAID-4",
@@ -4039,10 +4045,14 @@ static void pqi_free_irqs(struct pqi_ctrl_info *ctrl_info)
 static int pqi_enable_msix_interrupts(struct pqi_ctrl_info *ctrl_info)
 {
 	int num_vectors_enabled;
+	unsigned int flags = PCI_IRQ_MSIX;
+
+	if (!pqi_disable_managed_interrupts)
+		flags |= PCI_IRQ_AFFINITY;
 
 	num_vectors_enabled = pci_alloc_irq_vectors(ctrl_info->pci_dev,
 			PQI_MIN_MSIX_VECTORS, ctrl_info->num_queue_groups,
-			PCI_IRQ_MSIX | PCI_IRQ_AFFINITY);
+			flags);
 	if (num_vectors_enabled < 0) {
 		dev_err(&ctrl_info->pci_dev->dev,
 			"MSI-X init failed with error %d\n",
@@ -8588,6 +8598,7 @@ static struct pqi_ctrl_info *pqi_alloc_ctrl_info(int numa_node)
 	ctrl_info->max_write_raid_5_6 = PQI_DEFAULT_MAX_WRITE_RAID_5_6;
 	ctrl_info->max_write_raid_1_10_2drive = ~0;
 	ctrl_info->max_write_raid_1_10_3drive = ~0;
+	ctrl_info->disable_managed_interrupts = pqi_disable_managed_interrupts;
 
 	return ctrl_info;
 }