drivers/net/ethernet/sfc/tx_common.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /****************************************************************************
   3  * Driver for Solarflare network controllers and boards
   4  * Copyright 2018 Solarflare Communications Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published
   8  * by the Free Software Foundation, incorporated herein by reference.
   9  */
  10
  11 #include "net_driver.h"
  12 #include "efx.h"
  13 #include "nic_common.h"
  14 #include "tx_common.h"
  15
  16 static unsigned int efx_tx_cb_page_count(struct efx_tx_queue *tx_queue)
  17 {
  18         return DIV_ROUND_UP(tx_queue->ptr_mask + 1,
  19                             PAGE_SIZE >> EFX_TX_CB_ORDER);
  20 }
  21
  22 int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
  23 {
  24         struct efx_nic *efx = tx_queue->efx;
  25         unsigned int entries;
  26         int rc;
  27
  28         /* Create the smallest power-of-two aligned ring */
  29         entries = max(roundup_pow_of_two(efx->txq_entries), EFX_MIN_DMAQ_SIZE);
  30         EFX_WARN_ON_PARANOID(entries > EFX_MAX_DMAQ_SIZE);
  31         tx_queue->ptr_mask = entries - 1;
  32
  33         netif_dbg(efx, probe, efx->net_dev,
  34                   "creating TX queue %d size %#x mask %#x\n",
  35                   tx_queue->queue, efx->txq_entries, tx_queue->ptr_mask);
  36
  37         /* Allocate software ring */
  38         tx_queue->buffer = kcalloc(entries, sizeof(*tx_queue->buffer),
  39                                    GFP_KERNEL);
  40         if (!tx_queue->buffer)
  41                 return -ENOMEM;
  42
  43         tx_queue->cb_page = kcalloc(efx_tx_cb_page_count(tx_queue),
  44                                     sizeof(tx_queue->cb_page[0]), GFP_KERNEL);
  45         if (!tx_queue->cb_page) {
  46                 rc = -ENOMEM;
  47                 goto fail1;
  48         }
  49
  50         /* Allocate hardware ring */
  51         rc = efx_nic_probe_tx(tx_queue);
  52         if (rc)
  53                 goto fail2;
  54
  55         return 0;
  56
  57 fail2:
  58         kfree(tx_queue->cb_page);
  59         tx_queue->cb_page = NULL;
  60 fail1:
  61         kfree(tx_queue->buffer);
  62         tx_queue->buffer = NULL;
  63         return rc;
  64 }
  65
  66 void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
  67 {
  68         struct efx_nic *efx = tx_queue->efx;
  69
  70         netif_dbg(efx, drv, efx->net_dev,
  71                   "initialising TX queue %d\n", tx_queue->queue);
  72
  73         tx_queue->insert_count = 0;
  74         tx_queue->notify_count = 0;
  75         tx_queue->write_count = 0;
  76         tx_queue->packet_write_count = 0;
  77         tx_queue->old_write_count = 0;
  78         tx_queue->read_count = 0;
  79         tx_queue->old_read_count = 0;
  80         tx_queue->empty_read_count = 0 | EFX_EMPTY_COUNT_VALID;
  81         tx_queue->xmit_more_available = false;
  82         tx_queue->timestamping = (efx_ptp_use_mac_tx_timestamps(efx) &&
  83                                   tx_queue->channel == efx_ptp_channel(efx));
  84         tx_queue->completed_timestamp_major = 0;
  85         tx_queue->completed_timestamp_minor = 0;
  86
  87         tx_queue->xdp_tx = efx_channel_is_xdp_tx(tx_queue->channel);
  88
  89         /* Set up default function pointers. These may get replaced by
  90          * efx_nic_init_tx() based off NIC/queue capabilities.
  91          */
  92         tx_queue->handle_tso = efx_enqueue_skb_tso;
  93
  94         /* Set up TX descriptor ring */
  95         efx_nic_init_tx(tx_queue);
  96
  97         tx_queue->initialised = true;
  98 }
  99
 100 void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)
 101 {
 102         struct efx_tx_buffer *buffer;
 103
 104         netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
 105                   "shutting down TX queue %d\n", tx_queue->queue);
 106
 107         if (!tx_queue->buffer)
 108                 return;
 109
 110         /* Free any buffers left in the ring */
 111         while (tx_queue->read_count != tx_queue->write_count) {
 112                 unsigned int pkts_compl = 0, bytes_compl = 0;
 113
 114                 buffer = &tx_queue->buffer[tx_queue->read_count & tx_queue->ptr_mask];
 115                 efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
 116
 117                 ++tx_queue->read_count;
 118         }
 119         tx_queue->xmit_more_available = false;
 120         netdev_tx_reset_queue(tx_queue->core_txq);
 121 }
 122
 123 void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
 124 {
 125         int i;
 126
 127         if (!tx_queue->buffer)
 128                 return;
 129
 130         netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev,
 131                   "destroying TX queue %d\n", tx_queue->queue);
 132         efx_nic_remove_tx(tx_queue);
 133
 134         if (tx_queue->cb_page) {
 135                 for (i = 0; i < efx_tx_cb_page_count(tx_queue); i++)
 136                         efx_nic_free_buffer(tx_queue->efx,
 137                                             &tx_queue->cb_page[i]);
 138                 kfree(tx_queue->cb_page);
 139                 tx_queue->cb_page = NULL;
 140         }
 141
 142         kfree(tx_queue->buffer);
 143         tx_queue->buffer = NULL;
 144 }
 145
 146 void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
 147                         struct efx_tx_buffer *buffer,
 148                         unsigned int *pkts_compl,
 149                         unsigned int *bytes_compl)
 150 {
 151         if (buffer->unmap_len) {
 152                 struct device *dma_dev = &tx_queue->efx->pci_dev->dev;
 153                 dma_addr_t unmap_addr = buffer->dma_addr - buffer->dma_offset;
 154
 155                 if (buffer->flags & EFX_TX_BUF_MAP_SINGLE)
 156                         dma_unmap_single(dma_dev, unmap_addr, buffer->unmap_len,
 157                                          DMA_TO_DEVICE);
 158                 else
 159                         dma_unmap_page(dma_dev, unmap_addr, buffer->unmap_len,
 160                                        DMA_TO_DEVICE);
 161                 buffer->unmap_len = 0;
 162         }
 163
 164         if (buffer->flags & EFX_TX_BUF_SKB) {
 165                 struct sk_buff *skb = (struct sk_buff *)buffer->skb;
 166
 167                 EFX_WARN_ON_PARANOID(!pkts_compl || !bytes_compl);
 168                 (*pkts_compl)++;
 169                 (*bytes_compl) += skb->len;
 170                 if (tx_queue->timestamping &&
 171                     (tx_queue->completed_timestamp_major ||
 172                      tx_queue->completed_timestamp_minor)) {
 173                         struct skb_shared_hwtstamps hwtstamp;
 174
 175                         hwtstamp.hwtstamp =
 176                                 efx_ptp_nic_to_kernel_time(tx_queue);
 177                         skb_tstamp_tx(skb, &hwtstamp);
 178
 179                         tx_queue->completed_timestamp_major = 0;
 180                         tx_queue->completed_timestamp_minor = 0;
 181                 }
 182                 dev_consume_skb_any((struct sk_buff *)buffer->skb);
 183                 netif_vdbg(tx_queue->efx, tx_done, tx_queue->efx->net_dev,
 184                            "TX queue %d transmission id %x complete\n",
 185                            tx_queue->queue, tx_queue->read_count);
 186         } else if (buffer->flags & EFX_TX_BUF_XDP) {
 187                 xdp_return_frame_rx_napi(buffer->xdpf);
 188         }
 189
 190         buffer->len = 0;
 191         buffer->flags = 0;
 192 }
 193
 194 /* Remove packets from the TX queue
 195  *
 196  * This removes packets from the TX queue, up to and including the
 197  * specified index.
 198  */
 199 static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
 200                                 unsigned int index,
 201                                 unsigned int *pkts_compl,
 202                                 unsigned int *bytes_compl)
 203 {
 204         struct efx_nic *efx = tx_queue->efx;
 205         unsigned int stop_index, read_ptr;
 206
 207         stop_index = (index + 1) & tx_queue->ptr_mask;
 208         read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
 209
 210         while (read_ptr != stop_index) {
 211                 struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
 212
 213                 if (!efx_tx_buffer_in_use(buffer)) {
 214                         netif_err(efx, tx_err, efx->net_dev,
 215                                   "TX queue %d spurious TX completion id %d\n",
 216                                   tx_queue->queue, read_ptr);
 217                         efx_schedule_reset(efx, RESET_TYPE_TX_SKIP);
 218                         return;
 219                 }
 220
 221                 efx_dequeue_buffer(tx_queue, buffer, pkts_compl, bytes_compl);
 222
 223                 ++tx_queue->read_count;
 224                 read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
 225         }
 226 }
 227
 228 void efx_xmit_done_check_empty(struct efx_tx_queue *tx_queue)
 229 {
 230         if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) {
 231                 tx_queue->old_write_count = READ_ONCE(tx_queue->write_count);
 232                 if (tx_queue->read_count == tx_queue->old_write_count) {
 233                         /* Ensure that read_count is flushed. */
 234                         smp_mb();
 235                         tx_queue->empty_read_count =
 236                                 tx_queue->read_count | EFX_EMPTY_COUNT_VALID;
 237                 }
 238         }
 239 }
 240
 241 void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
 242 {
 243         unsigned int fill_level, pkts_compl = 0, bytes_compl = 0;
 244         struct efx_nic *efx = tx_queue->efx;
 245         struct efx_tx_queue *txq2;
 246
 247         EFX_WARN_ON_ONCE_PARANOID(index > tx_queue->ptr_mask);
 248
 249         efx_dequeue_buffers(tx_queue, index, &pkts_compl, &bytes_compl);
 250         tx_queue->pkts_compl += pkts_compl;
 251         tx_queue->bytes_compl += bytes_compl;
 252
 253         if (pkts_compl > 1)
 254                 ++tx_queue->merge_events;
 255
 256         /* See if we need to restart the netif queue.  This memory
 257          * barrier ensures that we write read_count (inside
 258          * efx_dequeue_buffers()) before reading the queue status.
 259          */
 260         smp_mb();
 261         if (unlikely(netif_tx_queue_stopped(tx_queue->core_txq)) &&
 262             likely(efx->port_enabled) &&
 263             likely(netif_device_present(efx->net_dev))) {
 264                 txq2 = efx_tx_queue_partner(tx_queue);
 265                 fill_level = max(tx_queue->insert_count - tx_queue->read_count,
 266                                  txq2->insert_count - txq2->read_count);
 267                 if (fill_level <= efx->txq_wake_thresh)
 268                         netif_tx_wake_queue(tx_queue->core_txq);
 269         }
 270
 271         efx_xmit_done_check_empty(tx_queue);
 272 }
 273
 274 /* Remove buffers put into a tx_queue for the current packet.
 275  * None of the buffers must have an skb attached.
 276  */
 277 void efx_enqueue_unwind(struct efx_tx_queue *tx_queue,
 278                         unsigned int insert_count)
 279 {
 280         struct efx_tx_buffer *buffer;
 281         unsigned int bytes_compl = 0;
 282         unsigned int pkts_compl = 0;
 283
 284         /* Work backwards until we hit the original insert pointer value */
 285         while (tx_queue->insert_count != insert_count) {
 286                 --tx_queue->insert_count;
 287                 buffer = __efx_tx_queue_get_insert_buffer(tx_queue);
 288                 efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
 289         }
 290 }
 291
 292 struct efx_tx_buffer *efx_tx_map_chunk(struct efx_tx_queue *tx_queue,
 293                                        dma_addr_t dma_addr, size_t len)
 294 {
 295         const struct efx_nic_type *nic_type = tx_queue->efx->type;
 296         struct efx_tx_buffer *buffer;
 297         unsigned int dma_len;
 298
 299         /* Map the fragment taking account of NIC-dependent DMA limits. */
 300         do {
 301                 buffer = efx_tx_queue_get_insert_buffer(tx_queue);
 302
 303                 if (nic_type->tx_limit_len)
 304                         dma_len = nic_type->tx_limit_len(tx_queue, dma_addr, len);
 305                 else
 306                         dma_len = len;
 307
 308                 buffer->len = dma_len;
 309                 buffer->dma_addr = dma_addr;
 310                 buffer->flags = EFX_TX_BUF_CONT;
 311                 len -= dma_len;
 312                 dma_addr += dma_len;
 313                 ++tx_queue->insert_count;
 314         } while (len);
 315
 316         return buffer;
 317 }
 318
 319 int efx_tx_tso_header_length(struct sk_buff *skb)
 320 {
 321         size_t header_len;
 322
 323         if (skb->encapsulation)
 324                 header_len = skb_inner_transport_header(skb) -
 325                                 skb->data +
 326                                 (inner_tcp_hdr(skb)->doff << 2u);
 327         else
 328                 header_len = skb_transport_header(skb) - skb->data +
 329                                 (tcp_hdr(skb)->doff << 2u);
 330         return header_len;
 331 }
 332
 333 /* Map all data from an SKB for DMA and create descriptors on the queue. */
 334 int efx_tx_map_data(struct efx_tx_queue *tx_queue, struct sk_buff *skb,
 335                     unsigned int segment_count)
 336 {
 337         struct efx_nic *efx = tx_queue->efx;
 338         struct device *dma_dev = &efx->pci_dev->dev;
 339         unsigned int frag_index, nr_frags;
 340         dma_addr_t dma_addr, unmap_addr;
 341         unsigned short dma_flags;
 342         size_t len, unmap_len;
 343
 344         nr_frags = skb_shinfo(skb)->nr_frags;
 345         frag_index = 0;
 346
 347         /* Map header data. */
 348         len = skb_headlen(skb);
 349         dma_addr = dma_map_single(dma_dev, skb->data, len, DMA_TO_DEVICE);
 350         dma_flags = EFX_TX_BUF_MAP_SINGLE;
 351         unmap_len = len;
 352         unmap_addr = dma_addr;
 353
 354         if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
 355                 return -EIO;
 356
 357         if (segment_count) {
 358                 /* For TSO we need to put the header in to a separate
 359                  * descriptor. Map this separately if necessary.
 360                  */
 361                 size_t header_len = efx_tx_tso_header_length(skb);
 362
 363                 if (header_len != len) {
 364                         tx_queue->tso_long_headers++;
 365                         efx_tx_map_chunk(tx_queue, dma_addr, header_len);
 366                         len -= header_len;
 367                         dma_addr += header_len;
 368                 }
 369         }
 370
 371         /* Add descriptors for each fragment. */
 372         do {
 373                 struct efx_tx_buffer *buffer;
 374                 skb_frag_t *fragment;
 375
 376                 buffer = efx_tx_map_chunk(tx_queue, dma_addr, len);
 377
 378                 /* The final descriptor for a fragment is responsible for
 379                  * unmapping the whole fragment.
 380                  */
 381                 buffer->flags = EFX_TX_BUF_CONT | dma_flags;
 382                 buffer->unmap_len = unmap_len;
 383                 buffer->dma_offset = buffer->dma_addr - unmap_addr;
 384
 385                 if (frag_index >= nr_frags) {
 386                         /* Store SKB details with the final buffer for
 387                          * the completion.
 388                          */
 389                         buffer->skb = skb;
 390                         buffer->flags = EFX_TX_BUF_SKB | dma_flags;
 391                         return 0;
 392                 }
 393
 394                 /* Move on to the next fragment. */
 395                 fragment = &skb_shinfo(skb)->frags[frag_index++];
 396                 len = skb_frag_size(fragment);
 397                 dma_addr = skb_frag_dma_map(dma_dev, fragment, 0, len,
 398                                             DMA_TO_DEVICE);
 399                 dma_flags = 0;
 400                 unmap_len = len;
 401                 unmap_addr = dma_addr;
 402
 403                 if (unlikely(dma_mapping_error(dma_dev, dma_addr)))
 404                         return -EIO;
 405         } while (1);
 406 }
 407
 408 unsigned int efx_tx_max_skb_descs(struct efx_nic *efx)
 409 {
 410         /* Header and payload descriptor for each output segment, plus
 411          * one for every input fragment boundary within a segment
 412          */
 413         unsigned int max_descs = EFX_TSO_MAX_SEGS * 2 + MAX_SKB_FRAGS;
 414
 415         /* Possibly one more per segment for option descriptors */
 416         if (efx_nic_rev(efx) >= EFX_REV_HUNT_A0)
 417                 max_descs += EFX_TSO_MAX_SEGS;
 418
 419         /* Possibly more for PCIe page boundaries within input fragments */
 420         if (PAGE_SIZE > EFX_PAGE_SIZE)
 421                 max_descs += max_t(unsigned int, MAX_SKB_FRAGS,
 422                                    DIV_ROUND_UP(GSO_MAX_SIZE, EFX_PAGE_SIZE));
 423
 424         return max_descs;
 425 }
 426
 427 /*
 428  * Fallback to software TSO.
 429  *
 430  * This is used if we are unable to send a GSO packet through hardware TSO.
 431  * This should only ever happen due to per-queue restrictions - unsupported
 432  * packets should first be filtered by the feature flags.
 433  *
 434  * Returns 0 on success, error code otherwise.
 435  */
 436 int efx_tx_tso_fallback(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 437 {
 438         struct sk_buff *segments, *next;
 439
 440         segments = skb_gso_segment(skb, 0);
 441         if (IS_ERR(segments))
 442                 return PTR_ERR(segments);
 443
 444         dev_consume_skb_any(skb);
 445
 446         skb_list_walk_safe(segments, skb, next) {
 447                 skb_mark_not_on_list(skb);
 448                 efx_enqueue_skb(tx_queue, skb);
 449         }
 450
 451         return 0;
 452 }