scsi: smartpqi: correct bdma hw bug

add workaround for BDMA hardware bug that can cause
hw to read up to 12 SGL elements (192 bytes) beyond the
last element in the list. This fix avoids IOMMU violations
Reviewed-by: Scott Benesh <scott.benesh@microsemi.com>
Signed-off-by: Kevin Barnett <kevin.barnett@microsemi.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/smartpqi/smartpqi_init.c

@@ -48,6 +48,8 @@
 #define DRIVER_NAME		"Microsemi PQI Driver (v" DRIVER_VERSION ")"
 #define DRIVER_NAME_SHORT	"smartpqi"
 
+#define PQI_EXTRA_SGL_MEMORY	(12 * sizeof(struct pqi_sg_descriptor))
+
 MODULE_AUTHOR("Microsemi");
 MODULE_DESCRIPTION("Driver for Microsemi Smart Family Controller version "
 	DRIVER_VERSION);
@@ -3202,6 +3204,8 @@ static int pqi_alloc_operational_queues(struct pqi_ctrl_info *ctrl_info)
 	alloc_length = (size_t)aligned_pointer +
 		PQI_QUEUE_ELEMENT_ARRAY_ALIGNMENT;
 
+	alloc_length += PQI_EXTRA_SGL_MEMORY;
+
 	ctrl_info->queue_memory_base =
 		dma_zalloc_coherent(&ctrl_info->pci_dev->dev,
 			alloc_length,
@@ -4319,7 +4323,8 @@ static void pqi_calculate_io_resources(struct pqi_ctrl_info *ctrl_info)
 	max_transfer_size = (max_sg_entries - 1) * PAGE_SIZE;
 
 	ctrl_info->sg_chain_buffer_length =
-		max_sg_entries * sizeof(struct pqi_sg_descriptor);
+		(max_sg_entries * sizeof(struct pqi_sg_descriptor)) +
+		PQI_EXTRA_SGL_MEMORY;
 	ctrl_info->sg_tablesize = max_sg_entries;
 	ctrl_info->max_sectors = max_transfer_size / 512;
 }