[PATCH 10/13] megaraid_sas: set virt_boundary_mask in the scsi host

[Christoph Hellwig <hch@lst.de>]

This ensures all proper DMA layer handling is taken care of by the
SCSI midlayer.  Note that the effect is global, as the IOMMU merging
is based off a paramters in struct device.  We could still turn if off
if no PCIe devices are present, but I don't know how to find that out.

Also remove the bogus nomerges flag, merges do take the virt_boundary
into account.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/megaraid/megaraid_sas_base.c   | 46 +++++----------------
 drivers/scsi/megaraid/megaraid_sas_fusion.c |  7 ++++
 2 files changed, 18 insertions(+), 35 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 3dd1df472dc6..20b3b3f8bc16 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -1870,39 +1870,6 @@ void megasas_set_dynamic_target_properties(struct scsi_device *sdev,
 	}
 }
 
-/*
- * megasas_set_nvme_device_properties -
- * set nomerges=2
- * set virtual page boundary = 4K (current mr_nvme_pg_size is 4K).
- * set maximum io transfer = MDTS of NVME device provided by MR firmware.
- *
- * MR firmware provides value in KB. Caller of this function converts
- * kb into bytes.
- *
- * e.a MDTS=5 means 2^5 * nvme page size. (In case of 4K page size,
- * MR firmware provides value 128 as (32 * 4K) = 128K.
- *
- * @sdev:				scsi device
- * @max_io_size:				maximum io transfer size
- *
- */
-static inline void
-megasas_set_nvme_device_properties(struct scsi_device *sdev, u32 max_io_size)
-{
-	struct megasas_instance *instance;
-	u32 mr_nvme_pg_size;
-
-	instance = (struct megasas_instance *)sdev->host->hostdata;
-	mr_nvme_pg_size = max_t(u32, instance->nvme_page_size,
-				MR_DEFAULT_NVME_PAGE_SIZE);
-
-	blk_queue_max_hw_sectors(sdev->request_queue, (max_io_size / 512));
-
-	blk_queue_flag_set(QUEUE_FLAG_NOMERGES, sdev->request_queue);
-	blk_queue_virt_boundary(sdev->request_queue, mr_nvme_pg_size - 1);
-}
-
-
 /*
  * megasas_set_static_target_properties -
  * Device property set by driver are static and it is not required to be
@@ -1961,8 +1928,10 @@ static void megasas_set_static_target_properties(struct scsi_device *sdev,
 		max_io_size_kb = le32_to_cpu(instance->tgt_prop->max_io_size_kb);
 	}
 
-	if (instance->nvme_page_size && max_io_size_kb)
-		megasas_set_nvme_device_properties(sdev, (max_io_size_kb << 10));
+	if (instance->nvme_page_size && max_io_size_kb) {
+		blk_queue_max_hw_sectors(sdev->request_queue,
+				(max_io_size_kb << 10) / 512);
+	}
 
 	scsi_change_queue_depth(sdev, device_qd);
 
@@ -6258,6 +6227,7 @@ static int megasas_start_aen(struct megasas_instance *instance)
 static int megasas_io_attach(struct megasas_instance *instance)
 {
 	struct Scsi_Host *host = instance->host;
+	u32 nvme_page_size = instance->nvme_page_size;
 
 	/*
 	 * Export parameters required by SCSI mid-layer
@@ -6298,6 +6268,12 @@ static int megasas_io_attach(struct megasas_instance *instance)
 	host->max_lun = MEGASAS_MAX_LUN;
 	host->max_cmd_len = 16;
 
+	if (nvme_page_size) {
+		if (nvme_page_size > MR_DEFAULT_NVME_PAGE_SIZE)
+			nvme_page_size = MR_DEFAULT_NVME_PAGE_SIZE;
+		host->virt_boundary_mask = nvme_page_size - 1;
+	}
+
 	/*
 	 * Notify the mid-layer about the new controller
 	 */
diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index 4dfa0685a86c..a9ff3a648e7b 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -1935,6 +1935,13 @@ megasas_is_prp_possible(struct megasas_instance *instance,
 			build_prp = true;
 	}
 
+/*
+ * XXX: All the code following should go away.  The block layer guarantees
+ * merging according to the virt boundary.  And while we might have had some
+ * issues with that in the past we fixed them, and any new bug should be fixed
+ * in the core code as well.
+ */
+
 /*
  * Below code detects gaps/holes in IO data buffers.
  * What does holes/gaps mean?
-- 
2.20.1