[PATCH v12 0/2] zfcp: Use DMA streaming API to map I/O

[PATCH v12 0/2] zfcp: Use DMA streaming API to map I/O

[M Nikhil]

In the existing zFCP driver, virtual addresses are translated directly
into bus (physical addresses) for DMA operations on all I/O buffers
passing from zFCP driver to the device.

Need for using DMA-API in zFCP driver:

In a Secure Execution environment, the host must ensure that device DMA
accesses are restricted to non-guest-private, page-sized memory blocks.
This prevents I/O failures that can occur when a device attempts to
access guest-private memory. Therefore, guest memory pages must be
prepared by the hypervisor before they become accessible to an I/O
device.

To support this requirement, the host Linux kernel must be reliably
informed whenever a memory region becomes eligible for device DMA access
and when that access must be revoked. This information must be
maintained correctly at least at page size granularity. To satisfy these
requirements, all I/O buffers used by the zFCP driver should be mapped
through the DMA API.

DMA API Integration in zFCP:

The zFCP driver is updated to use the DMA streaming API's to map all the
I/O buffers which will be passed to the device.
All zFCP I/O buffers (QTCB, SRB, CT/ELS and SCSI I/O) are represented as
scatter-gather lists and mapped through DMA API using dma_map_sgtable().
Once the DMA transfer is complete, the corresponding mappings are
released using dma_unmap_sgtable().

By routing all device-visible memory through the DMA mapping layer, the
driver ensures that:
1. DMA access is properly authorized before use.
2. DMA is revoked after use.
3. Secure Execution memory restrictions are honored.

Changes on the github can be found at:
https://github.ibm.com/M-Nikhil/linux/commits/zfcp_dma_api_implementation_io_path_version12

M Nikhil (2):
  zfcp: Replace sg-list with sg_table in zfcp_fsf_ct_els structure
  zfcp: Use DMA streaming API to map I/O

 drivers/s390/scsi/zfcp_aux.c  |  16 +++
 drivers/s390/scsi/zfcp_dbf.c  |  16 +--
 drivers/s390/scsi/zfcp_def.h  |   4 +
 drivers/s390/scsi/zfcp_ext.h  |  10 +-
 drivers/s390/scsi/zfcp_fc.c   |  36 +++--
 drivers/s390/scsi/zfcp_fsf.c  | 260 ++++++++++++++++++++++++++++------
 drivers/s390/scsi/zfcp_fsf.h  |   9 +-
 drivers/s390/scsi/zfcp_qdio.c |  37 +++--
 drivers/s390/scsi/zfcp_qdio.h |  27 ++--
 9 files changed, 321 insertions(+), 94 deletions(-)

-- 
2.53.0

[PATCH v12 1/2] zfcp: Replace sg-list with sg_table in zfcp_fsf_ct_els structure

[M Nikhil]

The zfcp_fsf_ct_els data structure is updated to replace the sg_req and
sg_resp members, which are of type struct scatterlist, with request and
response sg_table instances.

These sg_table structure reference the corresponding scatterlists
(sg_req and sg_resp) maintained in struct zfcp_fc_req.

These changes allows to track the original and mapped scatterlist nents
once zfcp is converted to use DMA-API for mapping the sg lists.

Signed-off-by: M Nikhil <nikh1092@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Reference-ID: SAN2402
---
 drivers/s390/scsi/zfcp_dbf.c | 16 ++++++++--------
 drivers/s390/scsi/zfcp_fc.c  | 36 ++++++++++++++++++++++++------------
 drivers/s390/scsi/zfcp_fsf.c |  6 ++++--
 drivers/s390/scsi/zfcp_fsf.h |  9 +++++----
 4 files changed, 41 insertions(+), 26 deletions(-)

diff --git a/drivers/s390/scsi/zfcp_dbf.c b/drivers/s390/scsi/zfcp_dbf.c
index 4217b74baa38..4232b1474a2f 100644
--- a/drivers/s390/scsi/zfcp_dbf.c
+++ b/drivers/s390/scsi/zfcp_dbf.c
@@ -581,9 +581,9 @@ void zfcp_dbf_san_req(char *tag, struct zfcp_fsf_req *fsf, u32 d_id)
 	if (unlikely(!debug_level_enabled(dbf->san, ZFCP_DBF_SAN_LEVEL)))
 		return;
 
-	length = (u16)zfcp_qdio_real_bytes(ct_els->req);
-	zfcp_dbf_san(tag, dbf, "san_req", ct_els->req, ZFCP_DBF_SAN_REQ,
-		     length, fsf->req_id, d_id, length);
+	length = (u16)zfcp_qdio_real_bytes(ct_els->sgt_req.sgl);
+	zfcp_dbf_san(tag, dbf, "san_req", ct_els->sgt_req.sgl,
+		     ZFCP_DBF_SAN_REQ, length, fsf->req_id, d_id, length);
 }
 
 static u16 zfcp_dbf_san_res_cap_len_if_gpn_ft(char *tag,
@@ -591,9 +591,9 @@ static u16 zfcp_dbf_san_res_cap_len_if_gpn_ft(char *tag,
 					      u16 len)
 {
 	struct zfcp_fsf_ct_els *ct_els = fsf->data;
-	struct fc_ct_hdr *reqh = sg_virt(ct_els->req);
+	struct fc_ct_hdr *reqh = sg_virt(ct_els->sgt_req.sgl);
 	struct fc_ns_gid_ft *reqn = (struct fc_ns_gid_ft *)(reqh + 1);
-	struct scatterlist *resp_entry = ct_els->resp;
+	struct scatterlist *resp_entry = ct_els->sgt_resp.sgl;
 	struct fc_ct_hdr *resph;
 	struct fc_gpn_ft_resp *acc;
 	int max_entries, x, last = 0;
@@ -662,9 +662,9 @@ void zfcp_dbf_san_res(char *tag, struct zfcp_fsf_req *fsf)
 	if (unlikely(!debug_level_enabled(dbf->san, ZFCP_DBF_SAN_LEVEL)))
 		return;
 
-	length = (u16)zfcp_qdio_real_bytes(ct_els->resp);
-	zfcp_dbf_san(tag, dbf, "san_res", ct_els->resp, ZFCP_DBF_SAN_RES,
-		     length, fsf->req_id, ct_els->d_id,
+	length = (u16)zfcp_qdio_real_bytes(ct_els->sgt_resp.sgl);
+	zfcp_dbf_san(tag, dbf, "san_res", ct_els->sgt_resp.sgl,
+		     ZFCP_DBF_SAN_RES, length, fsf->req_id, ct_els->d_id,
 		     zfcp_dbf_san_res_cap_len_if_gpn_ft(tag, fsf, length));
 }
 
diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
index 05d081297879..1fb6f2c3b607 100644
--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/drivers/s390/scsi/zfcp_fc.c
@@ -393,10 +393,12 @@ static int zfcp_fc_ns_gid_pn_request(struct zfcp_port *port,
 	fc_req->ct_els.port = port;
 	fc_req->ct_els.handler = zfcp_fc_complete;
 	fc_req->ct_els.handler_data = &completion;
-	fc_req->ct_els.req = &fc_req->sg_req;
-	fc_req->ct_els.resp = &fc_req->sg_rsp;
+	fc_req->ct_els.sgt_req.sgl = &fc_req->sg_req;
+	fc_req->ct_els.sgt_resp.sgl = &fc_req->sg_rsp;
 	sg_init_one(&fc_req->sg_req, gid_pn_req, sizeof(*gid_pn_req));
 	sg_init_one(&fc_req->sg_rsp, gid_pn_rsp, sizeof(*gid_pn_rsp));
+	fc_req->ct_els.sgt_req.orig_nents = sg_nents(&fc_req->sg_req);
+	fc_req->ct_els.sgt_resp.orig_nents = sg_nents(&fc_req->sg_rsp);
 
 	zfcp_fc_ct_ns_init(&gid_pn_req->ct_hdr,
 			   FC_NS_GID_PN, ZFCP_FC_CT_SIZE_PAGE);
@@ -558,12 +560,14 @@ static int zfcp_fc_adisc(struct zfcp_port *port)
 		return -ENOMEM;
 
 	fc_req->ct_els.port = port;
-	fc_req->ct_els.req = &fc_req->sg_req;
-	fc_req->ct_els.resp = &fc_req->sg_rsp;
+	fc_req->ct_els.sgt_req.sgl = &fc_req->sg_req;
+	fc_req->ct_els.sgt_resp.sgl = &fc_req->sg_rsp;
 	sg_init_one(&fc_req->sg_req, &fc_req->u.adisc.req,
 		    sizeof(struct fc_els_adisc));
 	sg_init_one(&fc_req->sg_rsp, &fc_req->u.adisc.rsp,
 		    sizeof(struct fc_els_adisc));
+	fc_req->ct_els.sgt_req.orig_nents = sg_nents(&fc_req->sg_req);
+	fc_req->ct_els.sgt_resp.orig_nents = sg_nents(&fc_req->sg_rsp);
 
 	fc_req->ct_els.handler = zfcp_fc_adisc_handler;
 	fc_req->ct_els.handler_data = fc_req;
@@ -706,8 +710,10 @@ static int zfcp_fc_send_gpn_ft(struct zfcp_fc_req *fc_req,
 
 	ct_els->handler = zfcp_fc_complete;
 	ct_els->handler_data = &completion;
-	ct_els->req = &fc_req->sg_req;
-	ct_els->resp = &fc_req->sg_rsp;
+	ct_els->sgt_req.sgl = &fc_req->sg_req;
+	ct_els->sgt_resp.sgl = &fc_req->sg_rsp;
+	ct_els->sgt_req.orig_nents = sg_nents(&fc_req->sg_req);
+	ct_els->sgt_resp.orig_nents = sg_nents(&fc_req->sg_rsp);
 
 	ret = zfcp_fsf_send_ct(&adapter->gs->ds, ct_els, NULL,
 			       ZFCP_FC_CTELS_TMO);
@@ -865,8 +871,10 @@ static int zfcp_fc_gspn(struct zfcp_adapter *adapter,
 
 	ct_els->handler = zfcp_fc_complete;
 	ct_els->handler_data = &completion;
-	ct_els->req = &fc_req->sg_req;
-	ct_els->resp = &fc_req->sg_rsp;
+	ct_els->sgt_req.sgl = &fc_req->sg_req;
+	ct_els->sgt_resp.sgl = &fc_req->sg_rsp;
+	ct_els->sgt_req.orig_nents = sg_nents(&fc_req->sg_req);
+	ct_els->sgt_resp.orig_nents = sg_nents(&fc_req->sg_rsp);
 
 	ret = zfcp_fsf_send_ct(&adapter->gs->ds, ct_els, NULL,
 			       ZFCP_FC_CTELS_TMO);
@@ -924,8 +932,10 @@ static void zfcp_fc_rspn(struct zfcp_adapter *adapter,
 
 	ct_els->handler = zfcp_fc_complete;
 	ct_els->handler_data = &completion;
-	ct_els->req = &fc_req->sg_req;
-	ct_els->resp = &fc_req->sg_rsp;
+	ct_els->sgt_req.sgl = &fc_req->sg_req;
+	ct_els->sgt_resp.sgl = &fc_req->sg_rsp;
+	ct_els->sgt_req.orig_nents = sg_nents(&fc_req->sg_req);
+	ct_els->sgt_resp.orig_nents = sg_nents(&fc_req->sg_rsp);
 
 	ret = zfcp_fsf_send_ct(&adapter->gs->ds, ct_els, NULL,
 			       ZFCP_FC_CTELS_TMO);
@@ -1090,8 +1100,10 @@ int zfcp_fc_exec_bsg_job(struct bsg_job *job)
 	if (!(atomic_read(&adapter->status) & ZFCP_STATUS_COMMON_OPEN))
 		return -EINVAL;
 
-	ct_els->req = job->request_payload.sg_list;
-	ct_els->resp = job->reply_payload.sg_list;
+	ct_els->sgt_req.sgl = job->request_payload.sg_list;
+	ct_els->sgt_resp.sgl = job->reply_payload.sg_list;
+	ct_els->sgt_req.orig_nents = sg_nents(ct_els->sgt_req.sgl);
+	ct_els->sgt_resp.orig_nents = sg_nents(ct_els->sgt_resp.sgl);
 	ct_els->handler_data = job;
 
 	switch (bsg_request->msgcode) {
diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index d407f16e77ef..a3b99839da9e 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -1242,7 +1242,8 @@ int zfcp_fsf_send_ct(struct zfcp_fc_wka_port *wka_port,
 	}
 
 	req->status |= ZFCP_STATUS_FSFREQ_CLEANUP;
-	ret = zfcp_fsf_setup_ct_els(req, ct->req, ct->resp, timeout);
+	ret = zfcp_fsf_setup_ct_els(req, ct->sgt_req.sgl, ct->sgt_resp.sgl,
+				    timeout);
 	if (ret)
 		goto failed_send;
 
@@ -1342,7 +1343,8 @@ int zfcp_fsf_send_els(struct zfcp_adapter *adapter, u32 d_id,
 	if (!zfcp_adapter_multi_buffer_active(adapter))
 		zfcp_qdio_sbal_limit(qdio, &req->qdio_req, 2);
 
-	ret = zfcp_fsf_setup_ct_els(req, els->req, els->resp, timeout);
+	ret = zfcp_fsf_setup_ct_els(req, els->sgt_req.sgl, els->sgt_resp.sgl,
+				    timeout);
 
 	if (ret)
 		goto failed_send;
diff --git a/drivers/s390/scsi/zfcp_fsf.h b/drivers/s390/scsi/zfcp_fsf.h
index 4b92e85ec71d..22e7fd933a78 100644
--- a/drivers/s390/scsi/zfcp_fsf.h
+++ b/drivers/s390/scsi/zfcp_fsf.h
@@ -487,8 +487,9 @@ struct zfcp_blk_drv_data {
 
 /**
  * struct zfcp_fsf_ct_els - zfcp data for ct or els request
- * @req: scatter-gather list for request, points to &zfcp_fc_req.sg_req or BSG
- * @resp: scatter-gather list for response, points to &zfcp_fc_req.sg_rsp or BSG
+ * @sgt_req: sg_table for request, its sgl points to &zfcp_fc_req.sg_req or BSG
+ * @sgt_resp: sg_table for response, its sgl points to &zfcp_fc_req.sg_resp
+ *            or BSG
  * @handler: handler function (called for response to the request)
  * @handler_data: data passed to handler function
  * @port: Optional pointer to port for zfcp internal ELS (only test link ADISC)
@@ -496,8 +497,8 @@ struct zfcp_blk_drv_data {
  * @d_id: Destination ID of either open WKA port for CT or of D_ID for ELS
  */
 struct zfcp_fsf_ct_els {
-	struct scatterlist *req;
-	struct scatterlist *resp;
+	struct sg_table sgt_req;
+	struct sg_table sgt_resp;
 	void (*handler)(void *);
 	void *handler_data;
 	struct zfcp_port *port;
-- 
2.53.0

[PATCH v12 2/2] zfcp: Use DMA streaming API to map I/O

[M Nikhil]

In the existing zFCP driver, virtual addresses are translated directly
into bus (physical) addresses for DMA operations on all I/O buffers
passed from the zFCP driver to the device.

Need for DMA API:

In secure execution environment, the host must ensure that device DMA
addresses are restricted to non-guest-private, page-sized memory blocks.
This prevents I/O failures that can occur when a device attempts to
access guest-private memory. Therefore, guest memory pages must be
prepared by the hypervisor before they become accessible to an I/O
device.

To support this requirement, the host linux kernel must be reliably
informed whenever a memory region becomes eligible for device DMA access
and when that access must be revoked. This information must be
maintained correctly at least at page level granularity.

To satisfy these requirements, all I/O buffers used by the zFCP driver
should be mapped through the DMA API.

DMA streaming API usage in zFCP:

Changes in this patch-series converts all I/O buffer mappings in the
zFCP driver to use the DMA streaming API. Specifically,
`dma_map_sgtable()` and `dma_unmap_sgtable()` are used to map and unmap
the scatter-gather lists.

All zFCP I/O buffers (QTCB, SRB, CT/ELS and SCSI I/O) are represented
using scatter-gather lists. The `sg_table` structure, which encapsulates
the scatterlist together with the original and mapped entry counts, is
used to manage DMA mappings efficiently.

For QTCB and status read buffers, which are not currently scatter-gather
based, `sg_init_one()` is used to initialize a single-entry scatterlist.
The resulting scatterlist is then associated with an `sg-table` by
initializing its `sgl` and `orig_nents` fields before DMA mapping.

For SCSI I/O, the  SCSI midlayer already maintains `sg_table` instances
for both normal and protection enabled SCSI commands. These sg tables
are mapped using the same DMA mapping functions.

DMA mapping is performed after the associated I/O buffers have been
populated or updated. Consequently, no explicit DMA synchronization for
device access before passing the DMA address to the adapter. On the
receive path, synchronization for CPU access is handled implicitly by
the DMA unmap operations.

Signed-off-by: M Nikhil <nikh1092@linux.ibm.com>
Reference-ID: SAN2402
---
v11 -> v12

- Modify comments to mention metadata is for SRB as well.
- Fix double unmap for exchange port and config data scenarios.
- Fix correct error value -EIO in mapping failure for QTCB.
---
 drivers/s390/scsi/zfcp_aux.c  |  16 +++
 drivers/s390/scsi/zfcp_def.h  |   4 +
 drivers/s390/scsi/zfcp_ext.h  |  10 +-
 drivers/s390/scsi/zfcp_fsf.c  | 260 ++++++++++++++++++++++++++++------
 drivers/s390/scsi/zfcp_qdio.c |  37 +++--
 drivers/s390/scsi/zfcp_qdio.h |  27 ++--
 6 files changed, 283 insertions(+), 71 deletions(-)

diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index 8ff7db7921b5..952cb80053ab 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -328,6 +328,19 @@ static void zfcp_destroy_adapter_work_queue(struct zfcp_adapter *adapter)
 
 }
 
+static int zfcp_set_dma_mask_for_adapter(struct zfcp_adapter *adapter)
+{
+	int ret;
+
+	ret = dma_set_mask_and_coherent(&adapter->ccw_device->dev,
+					DMA_BIT_MASK(64));
+	if (ret)
+		dev_err(&adapter->ccw_device->dev,
+			"Setting the DMA mask failed for the FCP device.\n");
+
+	return ret;
+}
+
 /**
  * zfcp_adapter_enqueue - enqueue a new adapter to the list
  * @ccw_device: pointer to the struct cc_device
@@ -403,6 +416,9 @@ struct zfcp_adapter *zfcp_adapter_enqueue(struct ccw_device *ccw_device)
 	rwlock_init(&adapter->erp_lock);
 	rwlock_init(&adapter->abort_lock);
 
+	if (zfcp_set_dma_mask_for_adapter(adapter))
+		goto failed;
+
 	if (zfcp_erp_thread_setup(adapter))
 		goto failed;
 
diff --git a/drivers/s390/scsi/zfcp_def.h b/drivers/s390/scsi/zfcp_def.h
index 6c761299a22f..5063921e8d93 100644
--- a/drivers/s390/scsi/zfcp_def.h
+++ b/drivers/s390/scsi/zfcp_def.h
@@ -322,6 +322,8 @@ static inline u64 zfcp_scsi_dev_lun(struct scsi_device *sdev)
  * @pool: reference to memory pool if used for this request
  * @issued: time when request was send (STCK)
  * @handler: handler which should be called to process response
+ * @metadata_sgt: sg_table for metadata of a QTCB or SRB request
+ * @metadata_sg: scatterlist for metadata of a QTCB or SRB request
  */
 struct zfcp_fsf_req {
 	struct list_head	list;
@@ -337,6 +339,8 @@ struct zfcp_fsf_req {
 	mempool_t		*pool;
 	unsigned long long	issued;
 	void			(*handler)(struct zfcp_fsf_req *);
+	struct sg_table		metadata_sgt;
+	struct scatterlist	metadata_sg;
 };
 
 static inline
diff --git a/drivers/s390/scsi/zfcp_ext.h b/drivers/s390/scsi/zfcp_ext.h
index 9f5152b42b0e..c31afc241644 100644
--- a/drivers/s390/scsi/zfcp_ext.h
+++ b/drivers/s390/scsi/zfcp_ext.h
@@ -148,14 +148,20 @@ enum zfcp_fsf_print_fmt {
 extern ssize_t zfcp_fsf_scnprint_fc_security(char *buf, size_t size,
 					     u32 fc_security,
 					     enum zfcp_fsf_print_fmt fmt);
+int zfcp_fsf_req_map_sg(struct zfcp_fsf_req *req, struct sg_table *sgt,
+			enum dma_data_direction dma_dir);
+void zfcp_fsf_req_unmap_sg(struct zfcp_fsf_req *req,
+			   struct sg_table *sgt,
+			   enum dma_data_direction dma_dir);
 
 /* zfcp_qdio.c */
 extern int zfcp_qdio_setup(struct zfcp_adapter *);
 extern void zfcp_qdio_destroy(struct zfcp_qdio *);
 extern int zfcp_qdio_sbal_get(struct zfcp_qdio *);
 extern int zfcp_qdio_send(struct zfcp_qdio *, struct zfcp_qdio_req *);
-extern int zfcp_qdio_sbals_from_sg(struct zfcp_qdio *, struct zfcp_qdio_req *,
-				   struct scatterlist *);
+int zfcp_qdio_sbals_from_sg(struct zfcp_qdio *qdio, struct sg_table *sgt,
+			    struct zfcp_fsf_req *req,
+			    enum dma_data_direction dma_dir);
 extern void zfcp_qdio_shost_update(struct zfcp_adapter *const adapter,
 				   const struct zfcp_qdio *const qdio);
 extern int zfcp_qdio_open(struct zfcp_qdio *);
diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index a3b99839da9e..371ef231d87b 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -14,6 +14,7 @@
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <scsi/fc/fc_els.h>
+#include <linux/dma-mapping.h>
 #include "zfcp_ext.h"
 #include "zfcp_fc.h"
 #include "zfcp_dbf.h"
@@ -84,6 +85,60 @@ static void zfcp_fsf_class_not_supp(struct zfcp_fsf_req *req)
 	req->status |= ZFCP_STATUS_FSFREQ_ERROR;
 }
 
+/**
+ * zfcp_fsf_req_map_sg - map the scattergather list for DMA transfer
+ * @req: pointer to zfcp_fsf_req
+ * @sgt: pointer to scattergather list table
+ * @dma_dir: DMA data direction
+ * Returns: 0 on success, -EIO otherwise
+ */
+int zfcp_fsf_req_map_sg(struct zfcp_fsf_req *req, struct sg_table *sgt,
+			enum dma_data_direction dma_dir)
+{
+	if (valid_dma_direction(dma_dir) && sgt->orig_nents) {
+		if (dma_map_sgtable(&req->adapter->ccw_device->dev, sgt,
+				    dma_dir, 0))
+			return -EIO;
+	} else if ((dma_dir == DMA_NONE) && sgt->orig_nents) {
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * zfcp_fsf_req_unmap_sg - unmap the scattergather list after DMA transfer
+ * @req: pointer to zfcp_fsf_req
+ * @sgt: pointer to scattergather list table
+ * @dma_dir: DMA direction of the sg
+ */
+void zfcp_fsf_req_unmap_sg(struct zfcp_fsf_req *req, struct sg_table *sgt,
+			   enum dma_data_direction dma_dir)
+{
+	/*
+	 * We still need the check for mapped sg count here to not perform
+	 * unmap for SCSI commands which have zero payload.
+	 */
+	if (!sgt->nents)
+		return;
+
+	dma_unmap_sgtable(&req->adapter->ccw_device->dev, sgt, dma_dir, 0);
+}
+
+/**
+ * zfcp_fsf_req_unmap_metadata - unmap the metadata associated with FSF req
+ * @req: pointer to zfcp_fsf_req
+ */
+static inline
+void zfcp_fsf_req_unmap_metadata(struct zfcp_fsf_req *const req)
+{
+	if (unlikely(zfcp_fsf_req_is_status_read_buffer(req)))
+		zfcp_fsf_req_unmap_sg(req, &req->metadata_sgt, DMA_FROM_DEVICE);
+	else
+		zfcp_fsf_req_unmap_sg(req, &req->metadata_sgt,
+				      DMA_BIDIRECTIONAL);
+}
+
 /**
  * zfcp_fsf_req_free - free memory used by fsf request
  * @req: pointer to struct zfcp_fsf_req
@@ -259,6 +314,8 @@ static void zfcp_fsf_status_read_handler(struct zfcp_fsf_req *req)
 	struct zfcp_adapter *adapter = req->adapter;
 	struct fsf_status_read_buffer *sr_buf = req->data;
 
+	zfcp_fsf_req_unmap_metadata(req);
+
 	if (req->status & ZFCP_STATUS_FSFREQ_DISMISSED) {
 		zfcp_dbf_hba_fsf_uss("fssrh_1", req);
 		mempool_free(virt_to_page(sr_buf), adapter->pool.sr_data);
@@ -457,6 +514,7 @@ static void zfcp_fsf_req_complete(struct zfcp_fsf_req *req)
 		return;
 	}
 
+	zfcp_fsf_req_unmap_metadata(req);
 	timer_delete_sync(&req->timer);
 	zfcp_fsf_protstatus_eval(req);
 	zfcp_fsf_fsfstatus_eval(req);
@@ -870,10 +928,27 @@ static struct zfcp_fsf_req *zfcp_fsf_req_create(struct zfcp_qdio *qdio,
 		req->qtcb->prefix.qtcb_version = FSF_QTCB_CURRENT_VERSION;
 		req->qtcb->header.req_handle = req->req_id;
 		req->qtcb->header.fsf_command = fsf_cmd;
-	}
 
-	zfcp_qdio_req_init(adapter->qdio, &req->qdio_req, req->req_id, sbtype,
-			   req->qtcb, sizeof(struct fsf_qtcb));
+		sg_init_one(&req->metadata_sg, req->qtcb,
+			    sizeof(struct fsf_qtcb));
+		req->metadata_sgt.sgl = &req->metadata_sg;
+		req->metadata_sgt.orig_nents = 1;
+
+		if (zfcp_fsf_req_map_sg(req, &req->metadata_sgt,
+					DMA_BIDIRECTIONAL)) {
+			zfcp_fsf_req_free(req);
+			return ERR_PTR(-EIO);
+		}
+
+		zfcp_qdio_req_init(adapter->qdio, &req->qdio_req, req->req_id,
+				   sbtype, true,
+				   sg_dma_len(req->metadata_sgt.sgl),
+				   sg_dma_address(req->metadata_sgt.sgl));
+	} else {
+		/* SRB */
+		zfcp_qdio_req_init(adapter->qdio, &req->qdio_req, req->req_id,
+				   sbtype, false, 0, 0);
+	}
 
 	return req;
 }
@@ -954,7 +1029,17 @@ int zfcp_fsf_status_read(struct zfcp_qdio *qdio)
 	memset(sr_buf, 0, sizeof(*sr_buf));
 	req->data = sr_buf;
 
-	zfcp_qdio_fill_next(qdio, &req->qdio_req, sr_buf, sizeof(*sr_buf));
+	sg_init_one(&req->metadata_sg, sr_buf, sizeof(*sr_buf));
+	req->metadata_sgt.sgl = &req->metadata_sg;
+	req->metadata_sgt.orig_nents = 1;
+
+	retval = zfcp_fsf_req_map_sg(req, &req->metadata_sgt, DMA_FROM_DEVICE);
+	if (unlikely(retval))
+		goto failed_dma_map;
+
+	zfcp_qdio_fill_next(qdio, &req->qdio_req,
+			    sg_dma_address(req->metadata_sgt.sgl),
+			    sg_dma_len(req->metadata_sgt.sgl));
 	zfcp_qdio_set_sbale_last(qdio, &req->qdio_req);
 
 	retval = zfcp_fsf_req_send(req);
@@ -965,6 +1050,8 @@ int zfcp_fsf_status_read(struct zfcp_qdio *qdio)
 	goto out;
 
 failed_req_send:
+	zfcp_fsf_req_unmap_metadata(req);
+failed_dma_map:
 	req->data = NULL;
 	mempool_free(virt_to_page(sr_buf), adapter->pool.sr_data);
 failed_buf:
@@ -1076,6 +1163,7 @@ struct zfcp_fsf_req *zfcp_fsf_abort_fcp_cmnd(struct scsi_cmnd *scmnd)
 	}
 
 out_error_free:
+	zfcp_fsf_req_unmap_metadata(req);
 	zfcp_fsf_req_free(req);
 	req = NULL;
 out:
@@ -1091,6 +1179,9 @@ static void zfcp_fsf_send_ct_handler(struct zfcp_fsf_req *req)
 
 	ct->status = -EINVAL;
 
+	zfcp_fsf_req_unmap_sg(req, &ct->sgt_req, DMA_TO_DEVICE);
+	zfcp_fsf_req_unmap_sg(req, &ct->sgt_resp, DMA_FROM_DEVICE);
+
 	if (req->status & ZFCP_STATUS_FSFREQ_ERROR)
 		goto skip_fsfstatus;
 
@@ -1130,19 +1221,41 @@ static void zfcp_fsf_send_ct_handler(struct zfcp_fsf_req *req)
 		ct->handler(ct->handler_data);
 }
 
-static void zfcp_fsf_setup_ct_els_unchained(struct zfcp_qdio *qdio,
-					    struct zfcp_qdio_req *q_req,
-					    struct scatterlist *sg_req,
-					    struct scatterlist *sg_resp)
+static int zfcp_fsf_setup_ct_els_unchained(struct zfcp_fsf_req *req,
+					   struct zfcp_qdio *qdio,
+					   struct sg_table *sg_req_table,
+					   struct sg_table *sg_resp_table)
 {
-	zfcp_qdio_fill_next(qdio, q_req, sg_virt(sg_req), sg_req->length);
-	zfcp_qdio_fill_next(qdio, q_req, sg_virt(sg_resp), sg_resp->length);
-	zfcp_qdio_set_sbale_last(qdio, q_req);
+	int retval = 0;
+
+	retval = zfcp_fsf_req_map_sg(req, sg_req_table, DMA_TO_DEVICE);
+	if (unlikely(retval))
+		goto err;
+
+	retval = zfcp_fsf_req_map_sg(req, sg_resp_table,
+				     DMA_FROM_DEVICE);
+	if (unlikely(retval))
+		goto err_unmap;
+
+	zfcp_qdio_fill_next(qdio, &req->qdio_req,
+			    sg_dma_address(sg_req_table->sgl),
+			    sg_dma_len(sg_req_table->sgl));
+	zfcp_qdio_fill_next(qdio, &req->qdio_req,
+			    sg_dma_address(sg_resp_table->sgl),
+			    sg_dma_len(sg_resp_table->sgl));
+	zfcp_qdio_set_sbale_last(qdio, &req->qdio_req);
+
+	return 0;
+
+err_unmap:
+	zfcp_fsf_req_unmap_sg(req, sg_req_table, DMA_TO_DEVICE);
+err:
+	return retval;
 }
 
 static int zfcp_fsf_setup_ct_els_sbals(struct zfcp_fsf_req *req,
-				       struct scatterlist *sg_req,
-				       struct scatterlist *sg_resp)
+				       struct sg_table *sgt_req,
+				       struct sg_table *sgt_resp)
 {
 	struct zfcp_adapter *adapter = req->adapter;
 	struct zfcp_qdio *qdio = adapter->qdio;
@@ -1150,57 +1263,70 @@ static int zfcp_fsf_setup_ct_els_sbals(struct zfcp_fsf_req *req,
 	u32 feat = adapter->adapter_features;
 
 	if (zfcp_adapter_multi_buffer_active(adapter)) {
-		if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_req))
+		if (zfcp_qdio_sbals_from_sg(qdio, sgt_req, req, DMA_TO_DEVICE))
 			return -EIO;
+
 		qtcb->bottom.support.req_buf_length =
-			zfcp_qdio_real_bytes(sg_req);
-		if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_resp))
-			return -EIO;
+			zfcp_qdio_real_bytes(sgt_req->sgl);
+
+		if (zfcp_qdio_sbals_from_sg(qdio, sgt_resp, req, DMA_FROM_DEVICE))
+			goto err_unmap;
+
 		qtcb->bottom.support.resp_buf_length =
-			zfcp_qdio_real_bytes(sg_resp);
+			zfcp_qdio_real_bytes(sgt_resp->sgl);
 
-		zfcp_qdio_set_data_div(qdio, &req->qdio_req, sg_nents(sg_req));
+		zfcp_qdio_set_data_div(qdio, &req->qdio_req,
+				       sg_nents(sgt_req->sgl));
 		zfcp_qdio_set_sbale_last(qdio, &req->qdio_req);
 		zfcp_qdio_set_scount(qdio, &req->qdio_req);
 		return 0;
 	}
 
 	/* use single, unchained SBAL if it can hold the request */
-	if (zfcp_qdio_sg_one_sbale(sg_req) && zfcp_qdio_sg_one_sbale(sg_resp)) {
-		zfcp_fsf_setup_ct_els_unchained(qdio, &req->qdio_req,
-						sg_req, sg_resp);
+	if (zfcp_qdio_sg_one_sbale(sgt_req->sgl) &&
+	    zfcp_qdio_sg_one_sbale(sgt_resp->sgl)) {
+		if (zfcp_fsf_setup_ct_els_unchained(req, qdio, sgt_req,
+						    sgt_resp))
+			return -EIO;
+
 		return 0;
 	}
 
 	if (!(feat & FSF_FEATURE_ELS_CT_CHAINED_SBALS))
 		return -EOPNOTSUPP;
 
-	if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_req))
+	if (zfcp_qdio_sbals_from_sg(qdio, sgt_req, req, DMA_TO_DEVICE))
 		return -EIO;
 
-	qtcb->bottom.support.req_buf_length = zfcp_qdio_real_bytes(sg_req);
+	qtcb->bottom.support.req_buf_length =
+		zfcp_qdio_real_bytes(sgt_req->sgl);
 
 	zfcp_qdio_set_sbale_last(qdio, &req->qdio_req);
 	zfcp_qdio_skip_to_last_sbale(qdio, &req->qdio_req);
 
-	if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_resp))
-		return -EIO;
+	if (zfcp_qdio_sbals_from_sg(qdio, sgt_resp, req, DMA_FROM_DEVICE))
+		goto err_unmap;
 
-	qtcb->bottom.support.resp_buf_length = zfcp_qdio_real_bytes(sg_resp);
+	qtcb->bottom.support.resp_buf_length =
+		zfcp_qdio_real_bytes(sgt_resp->sgl);
 
 	zfcp_qdio_set_sbale_last(qdio, &req->qdio_req);
 
 	return 0;
+
+err_unmap:
+	zfcp_fsf_req_unmap_sg(req, sgt_req, DMA_TO_DEVICE);
+	return -EIO;
 }
 
 static int zfcp_fsf_setup_ct_els(struct zfcp_fsf_req *req,
-				 struct scatterlist *sg_req,
-				 struct scatterlist *sg_resp,
+				 struct sg_table *sgt_req,
+				 struct sg_table *sgt_resp,
 				 unsigned int timeout)
 {
 	int ret;
 
-	ret = zfcp_fsf_setup_ct_els_sbals(req, sg_req, sg_resp);
+	ret = zfcp_fsf_setup_ct_els_sbals(req, sgt_req, sgt_resp);
 	if (ret)
 		return ret;
 
@@ -1242,8 +1368,7 @@ int zfcp_fsf_send_ct(struct zfcp_fc_wka_port *wka_port,
 	}
 
 	req->status |= ZFCP_STATUS_FSFREQ_CLEANUP;
-	ret = zfcp_fsf_setup_ct_els(req, ct->sgt_req.sgl, ct->sgt_resp.sgl,
-				    timeout);
+	ret = zfcp_fsf_setup_ct_els(req, &ct->sgt_req, &ct->sgt_resp, timeout);
 	if (ret)
 		goto failed_send;
 
@@ -1256,12 +1381,17 @@ int zfcp_fsf_send_ct(struct zfcp_fc_wka_port *wka_port,
 
 	ret = zfcp_fsf_req_send(req);
 	if (ret)
-		goto failed_send;
+		goto err_unmap;
+
 	/* NOTE: DO NOT TOUCH req PAST THIS POINT! */
 
 	goto out;
 
+err_unmap:
+	zfcp_fsf_req_unmap_sg(req, &ct->sgt_req, DMA_TO_DEVICE);
+	zfcp_fsf_req_unmap_sg(req, &ct->sgt_resp, DMA_FROM_DEVICE);
 failed_send:
+	zfcp_fsf_req_unmap_metadata(req);
 	zfcp_fsf_req_free(req);
 out:
 	spin_unlock_irq(&qdio->req_q_lock);
@@ -1275,6 +1405,9 @@ static void zfcp_fsf_send_els_handler(struct zfcp_fsf_req *req)
 
 	send_els->status = -EINVAL;
 
+	zfcp_fsf_req_unmap_sg(req, &send_els->sgt_req, DMA_TO_DEVICE);
+	zfcp_fsf_req_unmap_sg(req, &send_els->sgt_resp, DMA_FROM_DEVICE);
+
 	if (req->status & ZFCP_STATUS_FSFREQ_ERROR)
 		goto skip_fsfstatus;
 
@@ -1343,9 +1476,8 @@ int zfcp_fsf_send_els(struct zfcp_adapter *adapter, u32 d_id,
 	if (!zfcp_adapter_multi_buffer_active(adapter))
 		zfcp_qdio_sbal_limit(qdio, &req->qdio_req, 2);
 
-	ret = zfcp_fsf_setup_ct_els(req, els->sgt_req.sgl, els->sgt_resp.sgl,
+	ret = zfcp_fsf_setup_ct_els(req, &els->sgt_req, &els->sgt_resp,
 				    timeout);
-
 	if (ret)
 		goto failed_send;
 
@@ -1358,12 +1490,17 @@ int zfcp_fsf_send_els(struct zfcp_adapter *adapter, u32 d_id,
 
 	ret = zfcp_fsf_req_send(req);
 	if (ret)
-		goto failed_send;
+		goto err_unmap;
+
 	/* NOTE: DO NOT TOUCH req PAST THIS POINT! */
 
 	goto out;
 
+err_unmap:
+	zfcp_fsf_req_unmap_sg(req, &els->sgt_req, DMA_TO_DEVICE);
+	zfcp_fsf_req_unmap_sg(req, &els->sgt_resp, DMA_FROM_DEVICE);
 failed_send:
+	zfcp_fsf_req_unmap_metadata(req);
 	zfcp_fsf_req_free(req);
 out:
 	spin_unlock_irq(&qdio->req_q_lock);
@@ -1404,6 +1541,7 @@ int zfcp_fsf_exchange_config_data(struct zfcp_erp_action *erp_action)
 	zfcp_fsf_start_erp_timer(req);
 	retval = zfcp_fsf_req_send(req);
 	if (retval) {
+		zfcp_fsf_req_unmap_metadata(req);
 		zfcp_fsf_req_free(req);
 		erp_action->fsf_req_id = 0;
 	}
@@ -1469,6 +1607,8 @@ int zfcp_fsf_exchange_config_data_sync(struct zfcp_qdio *qdio,
 			retval = -EIO;
 		else if (req->status & ZFCP_STATUS_FSFREQ_XDATAINCOMPLETE)
 			retval = -EAGAIN;
+	} else {
+		zfcp_fsf_req_unmap_metadata(req);
 	}
 
 	zfcp_fsf_req_free(req);
@@ -1516,6 +1656,7 @@ int zfcp_fsf_exchange_port_data(struct zfcp_erp_action *erp_action)
 	zfcp_fsf_start_erp_timer(req);
 	retval = zfcp_fsf_req_send(req);
 	if (retval) {
+		zfcp_fsf_req_unmap_metadata(req);
 		zfcp_fsf_req_free(req);
 		erp_action->fsf_req_id = 0;
 	}
@@ -1578,6 +1719,8 @@ int zfcp_fsf_exchange_port_data_sync(struct zfcp_qdio *qdio,
 			retval = -EIO;
 		else if (req->status & ZFCP_STATUS_FSFREQ_XDATAINCOMPLETE)
 			retval = -EAGAIN;
+	} else {
+		zfcp_fsf_req_unmap_metadata(req);
 	}
 
 	zfcp_fsf_req_free(req);
@@ -1810,6 +1953,7 @@ int zfcp_fsf_open_port(struct zfcp_erp_action *erp_action)
 	zfcp_fsf_start_erp_timer(req);
 	retval = zfcp_fsf_req_send(req);
 	if (retval) {
+		zfcp_fsf_req_unmap_metadata(req);
 		zfcp_fsf_req_free(req);
 		erp_action->fsf_req_id = 0;
 		put_device(&port->dev);
@@ -1876,6 +2020,7 @@ int zfcp_fsf_close_port(struct zfcp_erp_action *erp_action)
 	zfcp_fsf_start_erp_timer(req);
 	retval = zfcp_fsf_req_send(req);
 	if (retval) {
+		zfcp_fsf_req_unmap_metadata(req);
 		zfcp_fsf_req_free(req);
 		erp_action->fsf_req_id = 0;
 	}
@@ -1950,8 +2095,10 @@ int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port)
 
 	zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT);
 	retval = zfcp_fsf_req_send(req);
-	if (retval)
+	if (retval) {
+		zfcp_fsf_req_unmap_metadata(req);
 		zfcp_fsf_req_free(req);
+	}
 	/* NOTE: DO NOT TOUCH req PAST THIS POINT! */
 out:
 	spin_unlock_irq(&qdio->req_q_lock);
@@ -2009,8 +2156,10 @@ int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port)
 
 	zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT);
 	retval = zfcp_fsf_req_send(req);
-	if (retval)
+	if (retval) {
+		zfcp_fsf_req_unmap_metadata(req);
 		zfcp_fsf_req_free(req);
+	}
 	/* NOTE: DO NOT TOUCH req PAST THIS POINT! */
 out:
 	spin_unlock_irq(&qdio->req_q_lock);
@@ -2103,6 +2252,7 @@ int zfcp_fsf_close_physical_port(struct zfcp_erp_action *erp_action)
 	zfcp_fsf_start_erp_timer(req);
 	retval = zfcp_fsf_req_send(req);
 	if (retval) {
+		zfcp_fsf_req_unmap_metadata(req);
 		zfcp_fsf_req_free(req);
 		erp_action->fsf_req_id = 0;
 	}
@@ -2227,6 +2377,7 @@ int zfcp_fsf_open_lun(struct zfcp_erp_action *erp_action)
 	zfcp_fsf_start_erp_timer(req);
 	retval = zfcp_fsf_req_send(req);
 	if (retval) {
+		zfcp_fsf_req_unmap_metadata(req);
 		zfcp_fsf_req_free(req);
 		erp_action->fsf_req_id = 0;
 	}
@@ -2316,6 +2467,7 @@ int zfcp_fsf_close_lun(struct zfcp_erp_action *erp_action)
 	zfcp_fsf_start_erp_timer(req);
 	retval = zfcp_fsf_req_send(req);
 	if (retval) {
+		zfcp_fsf_req_unmap_metadata(req);
 		zfcp_fsf_req_free(req);
 		erp_action->fsf_req_id = 0;
 	}
@@ -2474,6 +2626,13 @@ static void zfcp_fsf_fcp_cmnd_handler(struct zfcp_fsf_req *req)
 		return;
 	}
 
+	if ((scsi_get_prot_op(scpnt) != SCSI_PROT_NORMAL) &&
+	    scsi_prot_sg_count(scpnt))
+		zfcp_fsf_req_unmap_sg(req, &scpnt->prot_sdb->table,
+				      scpnt->sc_data_direction);
+
+	zfcp_fsf_req_unmap_sg(req, &scpnt->sdb.table, scpnt->sc_data_direction);
+
 	zfcp_fsf_fcp_handler_common(req, scpnt->device);
 
 	if (unlikely(req->status & ZFCP_STATUS_FSFREQ_ERROR)) {
@@ -2619,18 +2778,20 @@ int zfcp_fsf_fcp_cmnd(struct scsi_cmnd *scsi_cmnd)
 	    scsi_prot_sg_count(scsi_cmnd)) {
 		zfcp_qdio_set_data_div(qdio, &req->qdio_req,
 				       scsi_prot_sg_count(scsi_cmnd));
-		retval = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req,
-						 scsi_prot_sglist(scsi_cmnd));
+		retval = zfcp_qdio_sbals_from_sg(qdio,
+						 &scsi_cmnd->prot_sdb->table,
+						 req,
+						 scsi_cmnd->sc_data_direction);
 		if (retval)
 			goto failed_scsi_cmnd;
 		io->prot_data_length = zfcp_qdio_real_bytes(
 						scsi_prot_sglist(scsi_cmnd));
 	}
 
-	retval = zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req,
-					 scsi_sglist(scsi_cmnd));
+	retval = zfcp_qdio_sbals_from_sg(qdio, &scsi_cmnd->sdb.table, req,
+					 scsi_cmnd->sc_data_direction);
 	if (unlikely(retval))
-		goto failed_scsi_cmnd;
+		goto failed_normal_scsi_map;
 
 	zfcp_qdio_set_sbale_last(adapter->qdio, &req->qdio_req);
 	if (zfcp_adapter_multi_buffer_active(adapter))
@@ -2638,12 +2799,22 @@ int zfcp_fsf_fcp_cmnd(struct scsi_cmnd *scsi_cmnd)
 
 	retval = zfcp_fsf_req_send(req);
 	if (unlikely(retval))
-		goto failed_scsi_cmnd;
+		goto failed_req_send;
+
 	/* NOTE: DO NOT TOUCH req PAST THIS POINT! */
 
 	goto out;
 
+failed_req_send:
+	zfcp_fsf_req_unmap_sg(req, &scsi_cmnd->sdb.table,
+			      scsi_cmnd->sc_data_direction);
+failed_normal_scsi_map:
+	if ((scsi_get_prot_op(scsi_cmnd) != SCSI_PROT_NORMAL) &&
+	    scsi_prot_sg_count(scsi_cmnd))
+		zfcp_fsf_req_unmap_sg(req, &scsi_cmnd->prot_sdb->table,
+				      scsi_cmnd->sc_data_direction);
 failed_scsi_cmnd:
+	zfcp_fsf_req_unmap_metadata(req);
 	zfcp_fsf_req_free(req);
 	scsi_cmnd->host_scribble = NULL;
 out:
@@ -2719,6 +2890,7 @@ struct zfcp_fsf_req *zfcp_fsf_fcp_task_mgmt(struct scsi_device *sdev,
 		goto out;
 	}
 
+	zfcp_fsf_req_unmap_metadata(req);
 	zfcp_fsf_req_free(req);
 	req = NULL;
 out:
diff --git a/drivers/s390/scsi/zfcp_qdio.c b/drivers/s390/scsi/zfcp_qdio.c
index ce1af72d9b61..3b8fb3d28615 100644
--- a/drivers/s390/scsi/zfcp_qdio.c
+++ b/drivers/s390/scsi/zfcp_qdio.c
@@ -233,31 +233,40 @@ zfcp_qdio_sbale_next(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req)
 }
 
 /**
- * zfcp_qdio_sbals_from_sg - fill SBALs from scatter-gather list
+ * zfcp_qdio_sbals_from_sg - DMA map scatter-gather list and fill SBALs from it
  * @qdio: pointer to struct zfcp_qdio
- * @q_req: pointer to struct zfcp_qdio_req
- * @sg: scatter-gather list
- * Returns: zero or -EINVAL on error
+ * @sgt: pointer to scattergather list table
+ * @req: pointer to zfcp_fsf_req
+ * @dma_dir: DMA direction of I/O
+ * Returns: zero on success, -EINVAL or -EIO otherwise
  */
-int zfcp_qdio_sbals_from_sg(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req,
-			    struct scatterlist *sg)
+int zfcp_qdio_sbals_from_sg(struct zfcp_qdio *qdio, struct sg_table *sgt,
+			    struct zfcp_fsf_req *req,
+			    enum dma_data_direction dma_dir)
 {
 	struct qdio_buffer_element *sbale;
+	int i;
+	struct scatterlist *sg_element;
+
+	if (zfcp_fsf_req_map_sg(req, sgt, dma_dir))
+		return -EIO;
 
 	/* set storage-block type for this request */
-	sbale = zfcp_qdio_sbale_req(qdio, q_req);
-	sbale->sflags |= q_req->sbtype;
+	sbale = zfcp_qdio_sbale_req(qdio, &req->qdio_req);
+	sbale->sflags |= req->qdio_req.sbtype;
 
-	for (; sg; sg = sg_next(sg)) {
-		sbale = zfcp_qdio_sbale_next(qdio, q_req);
+	for_each_sgtable_dma_sg(sgt, sg_element, i) {
+		sbale = zfcp_qdio_sbale_next(qdio, &req->qdio_req);
 		if (!sbale) {
 			atomic_inc(&qdio->req_q_full);
-			zfcp_qdio_zero_sbals(qdio->req_q, q_req->sbal_first,
-					     q_req->sbal_number);
+			zfcp_qdio_zero_sbals(qdio->req_q,
+					     req->qdio_req.sbal_first,
+					     req->qdio_req.sbal_number);
+			zfcp_fsf_req_unmap_sg(req, sgt, dma_dir);
 			return -EINVAL;
 		}
-		sbale->addr = u64_to_dma64(sg_phys(sg));
-		sbale->length = sg->length;
+		sbale->addr = u64_to_dma64(sg_dma_address(sg_element));
+		sbale->length = sg_dma_len(sg_element);
 	}
 	return 0;
 }
diff --git a/drivers/s390/scsi/zfcp_qdio.h b/drivers/s390/scsi/zfcp_qdio.h
index 8f7d2ae94441..9f89f2975f6f 100644
--- a/drivers/s390/scsi/zfcp_qdio.h
+++ b/drivers/s390/scsi/zfcp_qdio.h
@@ -11,6 +11,7 @@
 #define ZFCP_QDIO_H
 
 #include <linux/interrupt.h>
+#include <linux/types.h>
 #include <asm/qdio.h>
 
 #define ZFCP_QDIO_SBALE_LEN	PAGE_SIZE
@@ -106,16 +107,19 @@ zfcp_qdio_sbale_curr(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req)
  * @q_req: the qdio request to start
  * @req_id: The request id
  * @sbtype: type flags to set for all sbals
- * @data: First data block
- * @len: Length of first data block
+ * @has_qtcb: FSF request has a QTCB
+ * @qtcb_len: Length of first data block QTCB, if any
+ * @qtcb_dma_handle: DMA handle of the QTCB, if any
  *
  * This is the start of putting the request into the queue, the last
  * step is passing the request to zfcp_qdio_send. The request queue
  * lock must be held during the whole process from init to send.
  */
 static inline
-void zfcp_qdio_req_init(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req,
-			u64 req_id, u8 sbtype, void *data, u32 len)
+void zfcp_qdio_req_init(struct zfcp_qdio *qdio,
+			struct zfcp_qdio_req *q_req, u64 req_id,
+			u8 sbtype, bool has_qtcb, u32 qtcb_len,
+			dma_addr_t qtcb_dma_handle)
 {
 	struct qdio_buffer_element *sbale;
 	int count = min(atomic_read(&qdio->req_q_free),
@@ -133,33 +137,34 @@ void zfcp_qdio_req_init(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req,
 	sbale->eflags = 0;
 	sbale->sflags = SBAL_SFLAGS0_COMMAND | sbtype;
 
-	if (unlikely(!data))
+	if (unlikely(!has_qtcb))
 		return;
 	sbale++;
-	sbale->addr = virt_to_dma64(data);
-	sbale->length = len;
+	sbale->addr = u64_to_dma64(qtcb_dma_handle);
+	sbale->length = qtcb_len;
 }
 
 /**
  * zfcp_qdio_fill_next - Fill next sbale, only for single sbal requests
  * @qdio: pointer to struct zfcp_qdio
  * @q_req: pointer to struct zfcp_queue_req
- * @data: pointer to data
+ * @dma_handle: dma address
  * @len: length of data
  *
  * This is only required for single sbal requests, calling it when
  * wrapping around to the next sbal is a bug.
  */
 static inline
-void zfcp_qdio_fill_next(struct zfcp_qdio *qdio, struct zfcp_qdio_req *q_req,
-			 void *data, u32 len)
+void zfcp_qdio_fill_next(struct zfcp_qdio *qdio,
+			 struct zfcp_qdio_req *q_req,
+			 dma_addr_t dma_handle, u32 len)
 {
 	struct qdio_buffer_element *sbale;
 
 	BUG_ON(q_req->sbale_curr == qdio->max_sbale_per_sbal - 1);
 	q_req->sbale_curr++;
 	sbale = zfcp_qdio_sbale_curr(qdio, q_req);
-	sbale->addr = virt_to_dma64(data);
+	sbale->addr = u64_to_dma64(dma_handle);
 	sbale->length = len;
 }
 
-- 
2.53.0

[PATCH v12 0/2] zfcp: Use DMA streaming API to map I/O

[M Nikhil]

In the existing zFCP driver, virtual addresses are translated directly
into bus (physical addresses) for DMA operations on all I/O buffers
passing from zFCP driver to the device.

Need for using DMA-API in zFCP driver:

In a Secure Execution environment, the host must ensure that device DMA
accesses are restricted to non-guest-private, page-sized memory blocks.
This prevents I/O failures that can occur when a device attempts to
access guest-private memory. Therefore, guest memory pages must be
prepared by the hypervisor before they become accessible to an I/O
device.

To support this requirement, the host Linux kernel must be reliably
informed whenever a memory region becomes eligible for device DMA access
and when that access must be revoked. This information must be
maintained correctly at least at page size granularity. To satisfy these
requirements, all I/O buffers used by the zFCP driver should be mapped
through the DMA API.

DMA API Integration in zFCP:

The zFCP driver is updated to use the DMA streaming API's to map all the
I/O buffers which will be passed to the device.
All zFCP I/O buffers (QTCB, SRB, CT/ELS and SCSI I/O) are represented as
scatter-gather lists and mapped through DMA API using dma_map_sgtable().
Once the DMA transfer is complete, the corresponding mappings are
released using dma_unmap_sgtable().

By routing all device-visible memory through the DMA mapping layer, the
driver ensures that:
1. DMA access is properly authorized before use.
2. DMA is revoked after use.
3. Secure Execution memory restrictions are honored.

M Nikhil (2):
  zfcp: Replace sg-list with sg_table in zfcp_fsf_ct_els structure
  zfcp: Use DMA streaming API to map I/O

 drivers/s390/scsi/zfcp_aux.c  |  16 +++
 drivers/s390/scsi/zfcp_dbf.c  |  16 +--
 drivers/s390/scsi/zfcp_def.h  |   4 +
 drivers/s390/scsi/zfcp_ext.h  |  10 +-
 drivers/s390/scsi/zfcp_fc.c   |  36 +++--
 drivers/s390/scsi/zfcp_fsf.c  | 260 ++++++++++++++++++++++++++++------
 drivers/s390/scsi/zfcp_fsf.h  |   9 +-
 drivers/s390/scsi/zfcp_qdio.c |  37 +++--
 drivers/s390/scsi/zfcp_qdio.h |  27 ++--
 9 files changed, 321 insertions(+), 94 deletions(-)

-- 
2.53.0