IB/iser: Use IB_WR_REG_MR_INTEGRITY for PI handover

Using this new API reduces iSER code complexity.
It also reduces the maximum number of work requests per task and the need
of dealing with multiple MRs (and their registrations and invalidations)
per task. It is done by using a single WR and a special MR type
(IB_MR_TYPE_INTEGRITY) for PI operation.

The setup of the tested benchmark:
- 2 servers with 24 cores (1 initiator and 1 target)
- 24 target sessions with 1 LUN each
- ramdisk backstore
- PI active

Performance results running fio (24 jobs, 128 iodepth) using
write_generate=0 and read_verify=0 (w/w.o patch):

bs IOPS(read) IOPS(write)
---- ---------- ----------
512 1236.6K/1164.3K 1357.2K/1332.8K
1k 1196.5K/1163.8K 1348.4K/1262.7K
2k 1016.7K/921950 1003.7K/931230
4k 662728/600545 595423/501513
8k 385954/384345 333775/277090
16k 222864/222820 170317/170671
32k 116869/114896 82331/82244
64k 55205/54931 40264/40021

Using write_generate=1 and read_verify=1 (w/w.o patch):

bs IOPS(read) IOPS(write)
---- ---------- ----------
512 1090.1K/1030.9K 1303.9K/1101.4K
1k 1057.7K/904583 1318.4K/988085
2k 965226/638799 1008.6K/692514
4k 555479/410151 542414/414517
8k 298675/224964 264729/237508
16k 133485/122481 164625/138647
32k 74329/67615 80143/78743
64k 35716/35519 39294/37334

We get performance improvement at all block sizes.
The most significant improvement is when writing 4k bs (almost 30% more
iops).

Signed-off-by: Israel Rukshin <[e-mail]>
Reviewed-by: Max Gurtovoy <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Reviewed-by: Sagi Grimberg <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/ulp/iser/iscsi_iser.h

···
 	ISCSI_TX_DATAOUT
 };
 
-/* Maximum number of work requests per task:
- * Data memory region local invalidate + fast registration
- * Protection memory region local invalidate + fast registration
- * Signature memory region local invalidate + fast registration
- * PDU send
+/*
+ * Maximum number of work requests per task
+ * (invalidate, registration, send)
  */
-#define ISER_MAX_WRS 7
+#define ISER_MAX_WRS 3
 
 /**
  * struct iser_tx_desc - iSER TX descriptor
···
  * @mapped:        Is the task header mapped
  * @wr_idx:        Current WR index
  * @wrs:           Array of WRs per task
- * @data_reg:      Data buffer registration details
- * @prot_reg:      Protection buffer registration details
- * @sig_attrs:     Signature attributes
  */
 struct iser_tx_desc {
 	struct iser_ctrl             iser_header;
···
 	union iser_wr {
 		struct ib_send_wr		send;
 		struct ib_reg_wr		fast_reg;
-		struct ib_sig_handover_wr	sig;
 	} wrs[ISER_MAX_WRS];
-	struct iser_mem_reg          data_reg;
-	struct iser_mem_reg          prot_reg;
-	struct ib_sig_attrs          sig_attrs;
 };
 
 #define ISER_RX_PAD_SIZE	(256 - (ISER_RX_PAYLOAD_SIZE + \
···
  *
  * @mr:         memory region
  * @fmr_pool:   pool of fmrs
+ * @sig_mr:     signature memory region
  * @page_vec:   fast reg page list used by fmr pool
  * @mr_valid:   is mr valid indicator
  */
···
 		struct ib_mr             *mr;
 		struct ib_fmr_pool       *fmr_pool;
 	};
+	struct ib_mr                     *sig_mr;
 	struct iser_page_vec             *page_vec;
 	u8				  mr_valid:1;
-};
-
-/**
- * struct iser_pi_context - Protection information context
- *
- * @rsc:             protection buffer registration resources
- * @sig_mr:          signature enable memory region
- * @sig_mr_valid:    is sig_mr valid indicator
- * @sig_protected:   is region protected indicator
- */
-struct iser_pi_context {
-	struct iser_reg_resources	rsc;
-	struct ib_mr                   *sig_mr;
-	u8                              sig_mr_valid:1;
-	u8                              sig_protected:1;
 };
 
 /**
···
  *
  * @list:           entry in connection fastreg pool
  * @rsc:            data buffer registration resources
- * @pi_ctx:         protection information context
+ * @sig_protected:  is region protected indicator
  */
 struct iser_fr_desc {
 	struct list_head		  list;
 	struct iser_reg_resources	  rsc;
-	struct iser_pi_context		 *pi_ctx;
+	bool				  sig_protected;
 	struct list_head                  all_list;
 };
 

drivers/infiniband/ulp/iser/iser_initiator.c

···
 static inline int
 iser_inv_desc(struct iser_fr_desc *desc, u32 rkey)
 {
-	if (likely(rkey == desc->rsc.mr->rkey)) {
-		desc->rsc.mr_valid = 0;
-	} else if (likely(desc->pi_ctx && rkey == desc->pi_ctx->sig_mr->rkey)) {
-		desc->pi_ctx->sig_mr_valid = 0;
-	} else {
+	if (unlikely((!desc->sig_protected && rkey != desc->rsc.mr->rkey) ||
+		     (desc->sig_protected && rkey != desc->rsc.sig_mr->rkey))) {
 		iser_err("Bogus remote invalidation for rkey %#x\n", rkey);
 		return -EINVAL;
 	}
+
+	desc->rsc.mr_valid = 0;
 
 	return 0;
 }
···
 
 	iser_task->prot[ISER_DIR_IN].data_len  = 0;
 	iser_task->prot[ISER_DIR_OUT].data_len = 0;
+
+	iser_task->prot[ISER_DIR_IN].dma_nents = 0;
+	iser_task->prot[ISER_DIR_OUT].dma_nents = 0;
 
 	memset(&iser_task->rdma_reg[ISER_DIR_IN], 0,
 	       sizeof(struct iser_mem_reg));

drivers/infiniband/ulp/iser/iser_memory.c

···
 
 static int
 iser_reg_sig_mr(struct iscsi_iser_task *iser_task,
-		struct iser_pi_context *pi_ctx,
-		struct iser_mem_reg *data_reg,
-		struct iser_mem_reg *prot_reg,
+		struct iser_data_buf *mem,
+		struct iser_data_buf *sig_mem,
+		struct iser_reg_resources *rsc,
 		struct iser_mem_reg *sig_reg)
 {
 	struct iser_tx_desc *tx_desc = &iser_task->desc;
-	struct ib_sig_attrs *sig_attrs = &tx_desc->sig_attrs;
 	struct ib_cqe *cqe = &iser_task->iser_conn->ib_conn.reg_cqe;
-	struct ib_sig_handover_wr *wr;
-	struct ib_mr *mr = pi_ctx->sig_mr;
+	struct ib_mr *mr = rsc->sig_mr;
+	struct ib_sig_attrs *sig_attrs = mr->sig_attrs;
+	struct ib_reg_wr *wr;
 	int ret;
 
 	memset(sig_attrs, 0, sizeof(*sig_attrs));
···
 
 	iser_set_prot_checks(iser_task->sc, &sig_attrs->check_mask);
 
-	if (pi_ctx->sig_mr_valid)
+	if (rsc->mr_valid)
 		iser_inv_rkey(iser_tx_next_wr(tx_desc), mr, cqe);
 
 	ib_update_fast_reg_key(mr, ib_inc_rkey(mr->rkey));
 
-	wr = container_of(iser_tx_next_wr(tx_desc), struct ib_sig_handover_wr,
-			  wr);
-	wr->wr.opcode = IB_WR_REG_SIG_MR;
+	ret = ib_map_mr_sg_pi(mr, mem->sg, mem->dma_nents, NULL,
+			      sig_mem->sg, sig_mem->dma_nents, NULL, SZ_4K);
+	if (unlikely(ret)) {
+		iser_err("failed to map PI sg (%d)\n",
+			 mem->dma_nents + sig_mem->dma_nents);
+		goto err;
+	}
+
+	wr = container_of(iser_tx_next_wr(tx_desc), struct ib_reg_wr, wr);
+	memset(wr, 0, sizeof(*wr));
+	wr->wr.opcode = IB_WR_REG_MR_INTEGRITY;
 	wr->wr.wr_cqe = cqe;
-	wr->wr.sg_list = &data_reg->sge;
-	wr->wr.num_sge = 1;
+	wr->wr.num_sge = 0;
 	wr->wr.send_flags = 0;
-	wr->sig_attrs = sig_attrs;
-	wr->sig_mr = mr;
-	if (scsi_prot_sg_count(iser_task->sc))
-		wr->prot = &prot_reg->sge;
-	else
-		wr->prot = NULL;
-	wr->access_flags = IB_ACCESS_LOCAL_WRITE |
-			   IB_ACCESS_REMOTE_READ |
-			   IB_ACCESS_REMOTE_WRITE;
-	pi_ctx->sig_mr_valid = 1;
+	wr->mr = mr;
+	wr->key = mr->rkey;
+	wr->access = IB_ACCESS_LOCAL_WRITE |
+		     IB_ACCESS_REMOTE_READ |
+		     IB_ACCESS_REMOTE_WRITE;
+	rsc->mr_valid = 1;
 
 	sig_reg->sge.lkey = mr->lkey;
 	sig_reg->rkey = mr->rkey;
-	sig_reg->sge.addr = 0;
-	sig_reg->sge.length = scsi_transfer_length(iser_task->sc);
+	sig_reg->sge.addr = mr->iova;
+	sig_reg->sge.length = mr->length;
 
 	iser_dbg("lkey=0x%x rkey=0x%x addr=0x%llx length=%u\n",
 		 sig_reg->sge.lkey, sig_reg->rkey, sig_reg->sge.addr,
···
 }
 
 static int
-iser_reg_prot_sg(struct iscsi_iser_task *task,
-		 struct iser_data_buf *mem,
-		 struct iser_fr_desc *desc,
-		 bool use_dma_key,
-		 struct iser_mem_reg *reg)
-{
-	struct iser_device *device = task->iser_conn->ib_conn.device;
-
-	if (use_dma_key)
-		return iser_reg_dma(device, mem, reg);
-
-	return device->reg_ops->reg_mem(task, mem, &desc->pi_ctx->rsc, reg);
-}
-
-static int
 iser_reg_data_sg(struct iscsi_iser_task *task,
 		 struct iser_data_buf *mem,
 		 struct iser_fr_desc *desc,
···
 	struct iser_device *device = ib_conn->device;
 	struct iser_data_buf *mem = &task->data[dir];
 	struct iser_mem_reg *reg = &task->rdma_reg[dir];
-	struct iser_mem_reg *data_reg;
 	struct iser_fr_desc *desc = NULL;
 	bool use_dma_key;
 	int err;
···
 		reg->mem_h = desc;
 	}
 
-	if (scsi_get_prot_op(task->sc) == SCSI_PROT_NORMAL)
-		data_reg = reg;
-	else
-		data_reg = &task->desc.data_reg;
-
-	err = iser_reg_data_sg(task, mem, desc, use_dma_key, data_reg);
-	if (unlikely(err))
-		goto err_reg;
-
-	if (scsi_get_prot_op(task->sc) != SCSI_PROT_NORMAL) {
-		struct iser_mem_reg *prot_reg = &task->desc.prot_reg;
-
-		if (scsi_prot_sg_count(task->sc)) {
-			mem = &task->prot[dir];
-			err = iser_reg_prot_sg(task, mem, desc,
-					       use_dma_key, prot_reg);
-			if (unlikely(err))
-				goto err_reg;
-		}
-
-		err = iser_reg_sig_mr(task, desc->pi_ctx, data_reg,
-				      prot_reg, reg);
+	if (scsi_get_prot_op(task->sc) == SCSI_PROT_NORMAL) {
+		err = iser_reg_data_sg(task, mem, desc, use_dma_key, reg);
+		if (unlikely(err))
+			goto err_reg;
+	} else {
+		err = iser_reg_sig_mr(task, mem, &task->prot[dir],
+				      &desc->rsc, reg);
 		if (unlikely(err))
 			goto err_reg;
 
-		desc->pi_ctx->sig_protected = 1;
+		desc->sig_protected = 1;
 	}
 
 	return 0;

drivers/infiniband/ulp/iser/iser_verbs.c

···
 	kfree(desc);
 }
 
-static int
-iser_alloc_reg_res(struct iser_device *device,
-		   struct ib_pd *pd,
-		   struct iser_reg_resources *res,
-		   unsigned int size)
-{
-	struct ib_device *ib_dev = device->ib_device;
-	enum ib_mr_type mr_type;
-	int ret;
-
-	if (ib_dev->attrs.device_cap_flags & IB_DEVICE_SG_GAPS_REG)
-		mr_type = IB_MR_TYPE_SG_GAPS;
-	else
-		mr_type = IB_MR_TYPE_MEM_REG;
-
-	res->mr = ib_alloc_mr(pd, mr_type, size);
-	if (IS_ERR(res->mr)) {
-		ret = PTR_ERR(res->mr);
-		iser_err("Failed to allocate ib_fast_reg_mr err=%d\n", ret);
-		return ret;
-	}
-	res->mr_valid = 0;
-
-	return 0;
-}
-
-static void
-iser_free_reg_res(struct iser_reg_resources *rsc)
-{
-	ib_dereg_mr(rsc->mr);
-}
-
-static int
-iser_alloc_pi_ctx(struct iser_device *device,
-		  struct ib_pd *pd,
-		  struct iser_fr_desc *desc,
-		  unsigned int size)
-{
-	struct iser_pi_context *pi_ctx = NULL;
-	int ret;
-
-	desc->pi_ctx = kzalloc(sizeof(*desc->pi_ctx), GFP_KERNEL);
-	if (!desc->pi_ctx)
-		return -ENOMEM;
-
-	pi_ctx = desc->pi_ctx;
-
-	ret = iser_alloc_reg_res(device, pd, &pi_ctx->rsc, size);
-	if (ret) {
-		iser_err("failed to allocate reg_resources\n");
-		goto alloc_reg_res_err;
-	}
-
-	pi_ctx->sig_mr = ib_alloc_mr(pd, IB_MR_TYPE_SIGNATURE, 2);
-	if (IS_ERR(pi_ctx->sig_mr)) {
-		ret = PTR_ERR(pi_ctx->sig_mr);
-		goto sig_mr_failure;
-	}
-	pi_ctx->sig_mr_valid = 0;
-	desc->pi_ctx->sig_protected = 0;
-
-	return 0;
-
-sig_mr_failure:
-	iser_free_reg_res(&pi_ctx->rsc);
-alloc_reg_res_err:
-	kfree(desc->pi_ctx);
-
-	return ret;
-}
-
-static void
-iser_free_pi_ctx(struct iser_pi_context *pi_ctx)
-{
-	iser_free_reg_res(&pi_ctx->rsc);
-	ib_dereg_mr(pi_ctx->sig_mr);
-	kfree(pi_ctx);
-}
-
 static struct iser_fr_desc *
 iser_create_fastreg_desc(struct iser_device *device,
 			 struct ib_pd *pd,
···
 			 unsigned int size)
 {
 	struct iser_fr_desc *desc;
+	struct ib_device *ib_dev = device->ib_device;
+	enum ib_mr_type mr_type;
 	int ret;
 
 	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
 	if (!desc)
 		return ERR_PTR(-ENOMEM);
 
-	ret = iser_alloc_reg_res(device, pd, &desc->rsc, size);
-	if (ret)
-		goto reg_res_alloc_failure;
+	if (ib_dev->attrs.device_cap_flags & IB_DEVICE_SG_GAPS_REG)
+		mr_type = IB_MR_TYPE_SG_GAPS;
+	else
+		mr_type = IB_MR_TYPE_MEM_REG;
+
+	desc->rsc.mr = ib_alloc_mr(pd, mr_type, size);
+	if (IS_ERR(desc->rsc.mr)) {
+		ret = PTR_ERR(desc->rsc.mr);
+		iser_err("Failed to allocate ib_fast_reg_mr err=%d\n", ret);
+		goto err_alloc_mr;
+	}
 
 	if (pi_enable) {
-		ret = iser_alloc_pi_ctx(device, pd, desc, size);
-		if (ret)
-			goto pi_ctx_alloc_failure;
+		desc->rsc.sig_mr = ib_alloc_mr_integrity(pd, size, size);
+		if (IS_ERR(desc->rsc.sig_mr)) {
+			ret = PTR_ERR(desc->rsc.sig_mr);
+			iser_err("Failed to allocate sig_mr err=%d\n", ret);
+			goto err_alloc_mr_integrity;
+		}
 	}
+	desc->rsc.mr_valid = 0;
 
 	return desc;
 
-pi_ctx_alloc_failure:
-	iser_free_reg_res(&desc->rsc);
-reg_res_alloc_failure:
+err_alloc_mr_integrity:
+	ib_dereg_mr(desc->rsc.mr);
+err_alloc_mr:
 	kfree(desc);
 
 	return ERR_PTR(ret);
+}
+
+static void iser_destroy_fastreg_desc(struct iser_fr_desc *desc)
+{
+	struct iser_reg_resources *res = &desc->rsc;
+
+	ib_dereg_mr(res->mr);
+	if (res->sig_mr) {
+		ib_dereg_mr(res->sig_mr);
+		res->sig_mr = NULL;
+	}
+	kfree(desc);
 }
 
 /**
···
 
 	list_for_each_entry_safe(desc, tmp, &fr_pool->all_list, all_list) {
 		list_del(&desc->all_list);
-		iser_free_reg_res(&desc->rsc);
-		if (desc->pi_ctx)
-			iser_free_pi_ctx(desc->pi_ctx);
-		kfree(desc);
+		iser_destroy_fastreg_desc(desc);
 		++i;
 	}
 
···
 	struct ib_device_attr *attr = &device->ib_device->attrs;
 	unsigned short sg_tablesize, sup_sg_tablesize;
 	unsigned short reserved_mr_pages;
+	u32 max_num_sg;
 
 	/*
 	 * FRs without SG_GAPS or FMRs can only map up to a (device) page per
···
 	else
 		reserved_mr_pages = 1;
 
+	if (iser_conn->ib_conn.pi_support)
+		max_num_sg = attr->max_pi_fast_reg_page_list_len;
+	else
+		max_num_sg = attr->max_fast_reg_page_list_len;
+
 	sg_tablesize = DIV_ROUND_UP(max_sectors * 512, SIZE_4K);
 	if (attr->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS)
 		sup_sg_tablesize =
 			min_t(
 			 uint, ISCSI_ISER_MAX_SG_TABLESIZE,
-			 attr->max_fast_reg_page_list_len - reserved_mr_pages);
+			 max_num_sg - reserved_mr_pages);
 	else
 		sup_sg_tablesize = ISCSI_ISER_MAX_SG_TABLESIZE;
 
···
 	struct ib_mr_status mr_status;
 	int ret;
 
-	if (desc && desc->pi_ctx->sig_protected) {
-		desc->pi_ctx->sig_protected = 0;
-		ret = ib_check_mr_status(desc->pi_ctx->sig_mr,
+	if (desc && desc->sig_protected) {
+		desc->sig_protected = 0;
+		ret = ib_check_mr_status(desc->rsc.sig_mr,
 					 IB_MR_CHECK_SIG_STATUS, &mr_status);
 		if (ret) {
 			pr_err("ib_check_mr_status failed, ret %d\n", ret);