net: ena: add handling of llq max tx burst size

There is a maximum TX burst size that the ENA device can handle.
It is exposed by the device to the driver and the driver
needs to comply with it to avoid bugs.

In this commit we:
1. Add ena_com_is_doorbell_needed(), which calculates the number of
   llq entries that will be used to hold a packet, and will return
   true if they exceed the number of allowed entries in a burst.
   If the function returns true, a doorbell needs to be invoked
   to send this packet in the next burst.

2. Follow the available entries in the current burst:
   - Every doorbell a new burst begins
   - With each write of an llq entry, the available entries in the
     current burst are decreased by 1.

Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: Sameeh Jubran <sameehj@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/amazon/ena/ena_admin_defs.h b/drivers/net/ethernet/amazon/ena/ena_admin_defs.h
index 9f80b73f90b141f97dff059bb23cbe23ba7dbe34..82cff1e120f8168a30940c2723aa4e8bc4c7a2a1 100644 (file)
--- a/drivers/net/ethernet/amazon/ena/ena_admin_defs.h
+++ b/drivers/net/ethernet/amazon/ena/ena_admin_defs.h
@@ -524,6 +524,11 @@ struct ena_admin_feature_llq_desc {
 
        /* the stride control the driver selected to use */
        u16 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.
+        */
+       u32 max_tx_burst_size;
 };
 
 struct ena_admin_queue_feature_desc {

diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c
index 7f8266b191ae7e5b712246b78689efe6584f7492..bd0d785b211e182f20c852c0b6b136614d2f5af2 100644 (file)
--- a/drivers/net/ethernet/amazon/ena/ena_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_com.c
@@ -396,6 +396,10 @@ 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;
+
+               if (io_sq->llq_info.max_entries_in_tx_burst > 0)
+                       io_sq->entries_in_tx_burst_left =
+                               io_sq->llq_info.max_entries_in_tx_burst;
        }
 
        io_sq->tail = 0;
@@ -727,6 +731,9 @@ static int ena_com_config_llq_info(struct ena_com_dev *ena_dev,
                       supported_feat, llq_info->descs_num_before_header);
        }
 
+       llq_info->max_entries_in_tx_burst =
+               (u16)(llq_features->max_tx_burst_size / llq_default_cfg->llq_ring_entry_size_value);
+
        rc = ena_com_set_llq(ena_dev);
        if (rc)
                pr_err("Cannot set LLQ configuration: %d\n", rc);

diff --git a/drivers/net/ethernet/amazon/ena/ena_com.h b/drivers/net/ethernet/amazon/ena/ena_com.h
index 078d6f2b4f398f52c4887c05a5cc35f51b57d9a1..f0cb043afcc3d89063f731af9278da9bebe98f2b 100644 (file)
--- a/drivers/net/ethernet/amazon/ena/ena_com.h
+++ b/drivers/net/ethernet/amazon/ena/ena_com.h
@@ -159,6 +159,7 @@ struct ena_com_llq_info {
        u16 desc_list_entry_size;
        u16 descs_num_before_header;
        u16 descs_per_entry;
+       u16 max_entries_in_tx_burst;
 };
 
 struct ena_com_io_cq {
@@ -238,6 +239,7 @@ struct ena_com_io_sq {
        u8 phase;
        u8 desc_entry_size;
        u8 dma_addr_bits;
+       u16 entries_in_tx_burst_left;
 } ____cacheline_aligned;
 
 struct ena_com_admin_cq {

diff --git a/drivers/net/ethernet/amazon/ena/ena_eth_com.c b/drivers/net/ethernet/amazon/ena/ena_eth_com.c
index f6c2d3855be8343f2dcf575aa2ba498f54076494..cad2b572808e84193040736bdeea15e45d908292 100644 (file)
--- a/drivers/net/ethernet/amazon/ena/ena_eth_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_eth_com.c
@@ -82,6 +82,17 @@ static inline int ena_com_write_bounce_buffer_to_dev(struct ena_com_io_sq *io_sq
        dst_tail_mask = io_sq->tail & (io_sq->q_depth - 1);
        dst_offset = dst_tail_mask * llq_info->desc_list_entry_size;
 
+       if (is_llq_max_tx_burst_exists(io_sq)) {
+               if (unlikely(!io_sq->entries_in_tx_burst_left)) {
+                       pr_err("Error: trying to send more packets than tx burst allows\n");
+                       return -ENOSPC;
+               }
+
+               io_sq->entries_in_tx_burst_left--;
+               pr_debug("decreasing entries_in_tx_burst_left of queue %d to %d\n",
+                        io_sq->qid, io_sq->entries_in_tx_burst_left);
+       }
+
        /* Make sure everything was written into the bounce buffer before
         * writing the bounce buffer to the device
         */
@@ -274,23 +285,6 @@ static inline u16 ena_com_cdesc_rx_pkt_get(struct ena_com_io_cq *io_cq,
        return count;
 }
 
-static inline bool ena_com_meta_desc_changed(struct ena_com_io_sq *io_sq,
-                                            struct ena_com_tx_ctx *ena_tx_ctx)
-{
-       int rc;
-
-       if (ena_tx_ctx->meta_valid) {
-               rc = memcmp(&io_sq->cached_tx_meta,
-                           &ena_tx_ctx->ena_meta,
-                           sizeof(struct ena_com_tx_meta));
-
-               if (unlikely(rc != 0))
-                       return true;
-       }
-
-       return false;
-}
-
 static inline int ena_com_create_and_store_tx_meta_desc(struct ena_com_io_sq *io_sq,
                                                        struct ena_com_tx_ctx *ena_tx_ctx)
 {

diff --git a/drivers/net/ethernet/amazon/ena/ena_eth_com.h b/drivers/net/ethernet/amazon/ena/ena_eth_com.h
index 340d02b64ca69293fdb5f579f9247002203f168c..0a3d9180e40ed83a7fe5d7deb4e4256a6199dd58 100644 (file)
--- a/drivers/net/ethernet/amazon/ena/ena_eth_com.h
+++ b/drivers/net/ethernet/amazon/ena/ena_eth_com.h
@@ -125,8 +125,55 @@ static inline bool ena_com_sq_have_enough_space(struct ena_com_io_sq *io_sq,
        return ena_com_free_desc(io_sq) > temp;
 }
 
+static inline bool ena_com_meta_desc_changed(struct ena_com_io_sq *io_sq,
+                                            struct ena_com_tx_ctx *ena_tx_ctx)
+{
+       if (!ena_tx_ctx->meta_valid)
+               return false;
+
+       return !!memcmp(&io_sq->cached_tx_meta,
+                       &ena_tx_ctx->ena_meta,
+                       sizeof(struct ena_com_tx_meta));
+}
+
+static inline bool is_llq_max_tx_burst_exists(struct ena_com_io_sq *io_sq)
+{
+       return (io_sq->mem_queue_type == ENA_ADMIN_PLACEMENT_POLICY_DEV) &&
+              io_sq->llq_info.max_entries_in_tx_burst > 0;
+}
+
+static inline bool ena_com_is_doorbell_needed(struct ena_com_io_sq *io_sq,
+                                             struct ena_com_tx_ctx *ena_tx_ctx)
+{
+       struct ena_com_llq_info *llq_info;
+       int descs_after_first_entry;
+       int num_entries_needed = 1;
+       u16 num_descs;
+
+       if (!is_llq_max_tx_burst_exists(io_sq))
+               return false;
+
+       llq_info = &io_sq->llq_info;
+       num_descs = ena_tx_ctx->num_bufs;
+
+       if (unlikely(ena_com_meta_desc_changed(io_sq, ena_tx_ctx)))
+               ++num_descs;
+
+       if (num_descs > llq_info->descs_num_before_header) {
+               descs_after_first_entry = num_descs - llq_info->descs_num_before_header;
+               num_entries_needed += DIV_ROUND_UP(descs_after_first_entry,
+                                                  llq_info->descs_per_entry);
+       }
+
+       pr_debug("queue: %d num_descs: %d num_entries_needed: %d\n", io_sq->qid,
+                num_descs, num_entries_needed);
+
+       return num_entries_needed > io_sq->entries_in_tx_burst_left;
+}
+
 static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq)
 {
+       u16 max_entries_in_tx_burst = io_sq->llq_info.max_entries_in_tx_burst;
        u16 tail = io_sq->tail;
 
        pr_debug("write submission queue doorbell for queue: %d tail: %d\n",
@@ -134,6 +181,12 @@ static inline int ena_com_write_sq_doorbell(struct ena_com_io_sq *io_sq)
 
        writel(tail, io_sq->db_addr);
 
+       if (is_llq_max_tx_burst_exists(io_sq)) {
+               pr_debug("reset available entries in tx burst for queue %d to %d\n",
+                        io_sq->qid, max_entries_in_tx_burst);
+               io_sq->entries_in_tx_burst_left = max_entries_in_tx_burst;
+       }
+
        return 0;
 }
 

diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index 9c83642922c77f5ef63501172ae56c681b7304a6..d2b82f917d3f5562d1f4ec61a171fa186021807b 100644 (file)
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -2172,6 +2172,13 @@ static netdev_tx_t ena_start_xmit(struct sk_buff *skb, struct net_device *dev)
        /* set flags and meta data */
        ena_tx_csum(&ena_tx_ctx, skb);
 
+       if (unlikely(ena_com_is_doorbell_needed(tx_ring->ena_com_io_sq, &ena_tx_ctx))) {
+               netif_dbg(adapter, tx_queued, dev,
+                         "llq tx max burst size of queue %d achieved, writing doorbell to send burst\n",
+                         qid);
+               ena_com_write_sq_doorbell(tx_ring->ena_com_io_sq);
+       }
+
        /* prepare the packet's descriptors to dma engine */
        rc = ena_com_prepare_tx(tx_ring->ena_com_io_sq, &ena_tx_ctx,
                                &nb_hw_desc);