From 011bdc28c7309197771b507ef9a28d4e1f1f0dfb Mon Sep 17 00:00:00 2001
From: Michal Krawczyk <mk@semihalf.com>
Date: Wed, 8 Apr 2020 10:29:00 +0200
Subject: [PATCH 093/177] net/ena/base: add accelerated LLQ mode

In order to use the accelerated LLQ (Low-lateny queue) mode, the driver
must limit the Tx burst and be aware that the device has the meta
caching disabled. In that situation, the meta descriptor must be valid
on each Tx packet.

Signed-off-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Igor Chauskin <igorch@amazon.com>
Reviewed-by: Guy Tzalik <gtzalik@amazon.com>
---
 drivers/net/ena/base/ena_com.c                | 20 +++++++-
 drivers/net/ena/base/ena_com.h                |  3 ++
 .../net/ena/base/ena_defs/ena_admin_defs.h    | 41 +++++++++++++--
 drivers/net/ena/base/ena_eth_com.c            | 51 +++++++++++++------
 4 files changed, 93 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ena/base/ena_com.c b/drivers/net/ena/base/ena_com.c
index 7e0aa21e03..962baf6024 100644
--- a/drivers/net/ena/base/ena_com.c
+++ b/drivers/net/ena/base/ena_com.c
@@ -378,6 +378,8 @@ static int ena_com_init_io_sq(struct ena_com_dev *ena_dev,
 		       0x0, io_sq->llq_info.desc_list_entry_size);
 		io_sq->llq_buf_ctrl.descs_left_in_line =
 			io_sq->llq_info.descs_num_before_header;
+		io_sq->disable_meta_caching =
+			io_sq->llq_info.disable_meta_caching;
 
 		if (io_sq->llq_info.max_entries_in_tx_burst > 0)
 			io_sq->entries_in_tx_burst_left =
@@ -595,6 +597,14 @@ static int ena_com_set_llq(struct ena_com_dev *ena_dev)
 	cmd.u.llq.desc_num_before_header_enabled = llq_info->descs_num_before_header;
 	cmd.u.llq.descriptors_stride_ctrl_enabled = llq_info->desc_stride_ctrl;
 
+	if (llq_info->disable_meta_caching)
+		cmd.u.llq.accel_mode.u.set.enabled_flags |=
+			BIT(ENA_ADMIN_DISABLE_META_CACHING);
+
+	if (llq_info->max_entries_in_tx_burst)
+		cmd.u.llq.accel_mode.u.set.enabled_flags |=
+			BIT(ENA_ADMIN_LIMIT_TX_BURST);
+
 	ret = ena_com_execute_admin_command(admin_queue,
 					    (struct ena_admin_aq_entry *)&cmd,
 					    sizeof(cmd),
@@ -714,9 +724,15 @@ static int ena_com_config_llq_info(struct ena_com_dev *ena_dev,
 			    supported_feat,
 			    llq_info->descs_num_before_header);
 	}
+	/* Check for accelerated queue supported */
+	llq_info->disable_meta_caching =
+		llq_features->accel_mode.u.get.supported_flags &
+		BIT(ENA_ADMIN_DISABLE_META_CACHING);
 
-	llq_info->max_entries_in_tx_burst =
-		(u16)(llq_features->max_tx_burst_size /	llq_default_cfg->llq_ring_entry_size_value);
+	if (llq_features->accel_mode.u.get.supported_flags & BIT(ENA_ADMIN_LIMIT_TX_BURST))
+		llq_info->max_entries_in_tx_burst =
+			llq_features->accel_mode.u.get.max_tx_burst_size /
+			llq_default_cfg->llq_ring_entry_size_value;
 
 	rc = ena_com_set_llq(ena_dev);
 	if (rc)
diff --git a/drivers/net/ena/base/ena_com.h b/drivers/net/ena/base/ena_com.h
index b613df1c77..07f63f44af 100644
--- a/drivers/net/ena/base/ena_com.h
+++ b/drivers/net/ena/base/ena_com.h
@@ -82,6 +82,7 @@ struct ena_com_llq_info {
 	u16 descs_num_before_header;
 	u16 descs_per_entry;
 	u16 max_entries_in_tx_burst;
+	bool disable_meta_caching;
 };
 
 struct ena_com_io_cq {
@@ -146,6 +147,8 @@ struct ena_com_io_sq {
 	enum queue_direction direction;
 	enum ena_admin_placement_policy_type mem_queue_type;
 
+	bool disable_meta_caching;
+
 	u32 msix_vector;
 	struct ena_com_tx_meta cached_tx_meta;
 	struct ena_com_llq_info llq_info;
diff --git a/drivers/net/ena/base/ena_defs/ena_admin_defs.h b/drivers/net/ena/base/ena_defs/ena_admin_defs.h
index fb4d4d03f0..6d266c4cf4 100644
--- a/drivers/net/ena/base/ena_defs/ena_admin_defs.h
+++ b/drivers/net/ena/base/ena_defs/ena_admin_defs.h
@@ -1,5 +1,5 @@
 /* SPDX-License-Identifier: BSD-3-Clause
- * Copyright (c) 2015-2019 Amazon.com, Inc. or its affiliates.
+ * Copyright (c) 2015-2020 Amazon.com, Inc. or its affiliates.
  * All rights reserved.
  */
 
@@ -469,6 +469,36 @@ enum ena_admin_llq_stride_ctrl {
 	ENA_ADMIN_MULTIPLE_DESCS_PER_ENTRY          = 2,
 };
 
+enum ena_admin_accel_mode_feat {
+	ENA_ADMIN_DISABLE_META_CACHING              = 0,
+	ENA_ADMIN_LIMIT_TX_BURST                    = 1,
+};
+
+struct ena_admin_accel_mode_get {
+	/* bit field of enum ena_admin_accel_mode_feat */
+	uint16_t supported_flags;
+
+	/* maximum burst size between two doorbells. The size is in bytes */
+	uint16_t max_tx_burst_size;
+};
+
+struct ena_admin_accel_mode_set {
+	/* bit field of enum ena_admin_accel_mode_feat */
+	uint16_t enabled_flags;
+
+	uint16_t reserved;
+};
+
+struct ena_admin_accel_mode_req {
+	union {
+		uint32_t raw[2];
+
+		struct ena_admin_accel_mode_get get;
+
+		struct ena_admin_accel_mode_set set;
+	} u;
+};
+
 struct ena_admin_feature_llq_desc {
 	uint32_t max_llq_num;
 
@@ -514,10 +544,13 @@ struct ena_admin_feature_llq_desc {
 	/* the stride control the driver selected to use */
 	uint16_t descriptors_stride_ctrl_enabled;
 
-	/* Maximum size in bytes taken by llq entries in a single tx burst.
-	 * Set to 0 when there is no such limit.
+	/* reserved */
+	uint32_t reserved1;
+
+	/* accelerated low latency queues requirement. Driver needs to
+	 * support those requirements in order to use accelerated LLQ
 	 */
-	uint32_t max_tx_burst_size;
+	struct ena_admin_accel_mode_req accel_mode;
 };
 
 struct ena_admin_queue_ext_feature_fields {
diff --git a/drivers/net/ena/base/ena_eth_com.c b/drivers/net/ena/base/ena_eth_com.c
index d4d44226df..8f9528bdff 100644
--- a/drivers/net/ena/base/ena_eth_com.c
+++ b/drivers/net/ena/base/ena_eth_com.c
@@ -1,5 +1,5 @@
 /* SPDX-License-Identifier: BSD-3-Clause
- * Copyright (c) 2015-2019 Amazon.com, Inc. or its affiliates.
+ * Copyright (c) 2015-2020 Amazon.com, Inc. or its affiliates.
  * All rights reserved.
  */
 
@@ -258,11 +258,10 @@ static u16 ena_com_cdesc_rx_pkt_get(struct ena_com_io_cq *io_cq,
 	return count;
 }
 
-static int ena_com_create_and_store_tx_meta_desc(struct ena_com_io_sq *io_sq,
-							struct ena_com_tx_ctx *ena_tx_ctx)
+static int ena_com_create_meta(struct ena_com_io_sq *io_sq,
+			       struct ena_com_tx_meta *ena_meta)
 {
 	struct ena_eth_io_tx_meta_desc *meta_desc = NULL;
-	struct ena_com_tx_meta *ena_meta = &ena_tx_ctx->ena_meta;
 
 	meta_desc = get_sq_desc(io_sq);
 	memset(meta_desc, 0x0, sizeof(struct ena_eth_io_tx_meta_desc));
@@ -282,12 +281,13 @@ static int ena_com_create_and_store_tx_meta_desc(struct ena_com_io_sq *io_sq,
 
 	/* Extended meta desc */
 	meta_desc->len_ctrl |= ENA_ETH_IO_TX_META_DESC_ETH_META_TYPE_MASK;
-	meta_desc->len_ctrl |= ENA_ETH_IO_TX_META_DESC_META_STORE_MASK;
 	meta_desc->len_ctrl |= (io_sq->phase <<
 		ENA_ETH_IO_TX_META_DESC_PHASE_SHIFT) &
 		ENA_ETH_IO_TX_META_DESC_PHASE_MASK;
 
 	meta_desc->len_ctrl |= ENA_ETH_IO_TX_META_DESC_FIRST_MASK;
+	meta_desc->len_ctrl |= ENA_ETH_IO_TX_META_DESC_META_STORE_MASK;
+
 	meta_desc->word2 |= ena_meta->l3_hdr_len &
 		ENA_ETH_IO_TX_META_DESC_L3_HDR_LEN_MASK;
 	meta_desc->word2 |= (ena_meta->l3_hdr_offset <<
@@ -298,13 +298,34 @@ static int ena_com_create_and_store_tx_meta_desc(struct ena_com_io_sq *io_sq,
 		ENA_ETH_IO_TX_META_DESC_L4_HDR_LEN_IN_WORDS_SHIFT) &
 		ENA_ETH_IO_TX_META_DESC_L4_HDR_LEN_IN_WORDS_MASK;
 
-	meta_desc->len_ctrl |= ENA_ETH_IO_TX_META_DESC_META_STORE_MASK;
+	return ena_com_sq_update_tail(io_sq);
+}
 
-	/* Cached the meta desc */
-	memcpy(&io_sq->cached_tx_meta, ena_meta,
-	       sizeof(struct ena_com_tx_meta));
+static int ena_com_create_and_store_tx_meta_desc(struct ena_com_io_sq *io_sq,
+						 struct ena_com_tx_ctx *ena_tx_ctx,
+						 bool *have_meta)
+{
+	struct ena_com_tx_meta *ena_meta = &ena_tx_ctx->ena_meta;
 
-	return ena_com_sq_update_tail(io_sq);
+	/* When disable meta caching is set, don't bother to save the meta and
+	 * compare it to the stored version, just create the meta
+	 */
+	if (io_sq->disable_meta_caching) {
+		if (unlikely(!ena_tx_ctx->meta_valid))
+			return ENA_COM_INVAL;
+
+		*have_meta = true;
+		return ena_com_create_meta(io_sq, ena_meta);
+	} else if (ena_com_meta_desc_changed(io_sq, ena_tx_ctx)) {
+		*have_meta = true;
+		/* Cache the meta desc */
+		memcpy(&io_sq->cached_tx_meta, ena_meta,
+		       sizeof(struct ena_com_tx_meta));
+		return ena_com_create_meta(io_sq, ena_meta);
+	} else {
+		*have_meta = false;
+		return ENA_COM_OK;
+	}
 }
 
 static void ena_com_rx_set_flags(struct ena_com_rx_ctx *ena_rx_ctx,
@@ -380,12 +401,10 @@ int ena_com_prepare_tx(struct ena_com_io_sq *io_sq,
 	if (unlikely(rc))
 		return rc;
 
-	have_meta = ena_tx_ctx->meta_valid && ena_com_meta_desc_changed(io_sq,
-			ena_tx_ctx);
-	if (have_meta) {
-		rc = ena_com_create_and_store_tx_meta_desc(io_sq, ena_tx_ctx);
-		if (unlikely(rc))
-			return rc;
+	rc = ena_com_create_and_store_tx_meta_desc(io_sq, ena_tx_ctx, &have_meta);
+	if (unlikely(rc)) {
+		ena_trc_err("failed to create and store tx meta desc\n");
+		return rc;
 	}
 
 	/* If the caller doesn't want to send packets */
-- 
2.25.1

