drivers/net/ethernet/sfc/tx_tso.c

   1 /****************************************************************************
   2  * Driver for Solarflare network controllers and boards
   3  * Copyright 2005-2006 Fen Systems Ltd.
   4  * Copyright 2005-2015 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 <linux/pci.h>
  12 #include <linux/tcp.h>
  13 #include <linux/ip.h>
  14 #include <linux/in.h>
  15 #include <linux/ipv6.h>
  16 #include <linux/slab.h>
  17 #include <net/ipv6.h>
  18 #include <linux/if_ether.h>
  19 #include <linux/highmem.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/cache.h>
  22 #include "net_driver.h"
  23 #include "efx.h"
  24 #include "io.h"
  25 #include "nic.h"
  26 #include "tx.h"
  27 #include "workarounds.h"
  28 #include "ef10_regs.h"
  29
  30 /* Efx legacy TCP segmentation acceleration.
  31  *
  32  * Utilises firmware support to go faster than GSO (but not as fast as TSOv2).
  33  *
  34  * Requires TX checksum offload support.
  35  */
  36
  37 #define PTR_DIFF(p1, p2)  ((u8 *)(p1) - (u8 *)(p2))
  38
  39 /**
  40  * struct tso_state - TSO state for an SKB
  41  * @out_len: Remaining length in current segment
  42  * @seqnum: Current sequence number
  43  * @ipv4_id: Current IPv4 ID, host endian
  44  * @packet_space: Remaining space in current packet
  45  * @dma_addr: DMA address of current position
  46  * @in_len: Remaining length in current SKB fragment
  47  * @unmap_len: Length of SKB fragment
  48  * @unmap_addr: DMA address of SKB fragment
  49  * @protocol: Network protocol (after any VLAN header)
  50  * @ip_off: Offset of IP header
  51  * @tcp_off: Offset of TCP header
  52  * @header_len: Number of bytes of header
  53  * @ip_base_len: IPv4 tot_len or IPv6 payload_len, before TCP payload
  54  * @header_dma_addr: Header DMA address
  55  * @header_unmap_len: Header DMA mapped length
  56  *
  57  * The state used during segmentation.  It is put into this data structure
  58  * just to make it easy to pass into inline functions.
  59  */
  60 struct tso_state {
  61         /* Output position */
  62         unsigned int out_len;
  63         unsigned int seqnum;
  64         u16 ipv4_id;
  65         unsigned int packet_space;
  66
  67         /* Input position */
  68         dma_addr_t dma_addr;
  69         unsigned int in_len;
  70         unsigned int unmap_len;
  71         dma_addr_t unmap_addr;
  72
  73         __be16 protocol;
  74         unsigned int ip_off;
  75         unsigned int tcp_off;
  76         unsigned int header_len;
  77         unsigned int ip_base_len;
  78         dma_addr_t header_dma_addr;
  79         unsigned int header_unmap_len;
  80 };
  81
  82 static inline void prefetch_ptr(struct efx_tx_queue *tx_queue)
  83 {
  84         unsigned int insert_ptr = efx_tx_queue_get_insert_index(tx_queue);
  85         char *ptr;
  86
  87         ptr = (char *) (tx_queue->buffer + insert_ptr);
  88         prefetch(ptr);
  89         prefetch(ptr + 0x80);
  90
  91         ptr = (char *) (((efx_qword_t *)tx_queue->txd.buf.addr) + insert_ptr);
  92         prefetch(ptr);
  93         prefetch(ptr + 0x80);
  94 }
  95
  96 /**
  97  * efx_tx_queue_insert - push descriptors onto the TX queue
  98  * @tx_queue:           Efx TX queue
  99  * @dma_addr:           DMA address of fragment
 100  * @len:                Length of fragment
 101  * @final_buffer:       The final buffer inserted into the queue
 102  *
 103  * Push descriptors onto the TX queue.
 104  */
 105 static void efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
 106                                 dma_addr_t dma_addr, unsigned int len,
 107                                 struct efx_tx_buffer **final_buffer)
 108 {
 109         struct efx_tx_buffer *buffer;
 110         unsigned int dma_len;
 111
 112         EFX_WARN_ON_ONCE_PARANOID(len <= 0);
 113
 114         while (1) {
 115                 buffer = efx_tx_queue_get_insert_buffer(tx_queue);
 116                 ++tx_queue->insert_count;
 117
 118                 EFX_WARN_ON_ONCE_PARANOID(tx_queue->insert_count -
 119                                           tx_queue->read_count >=
 120                                           tx_queue->efx->txq_entries);
 121
 122                 buffer->dma_addr = dma_addr;
 123
 124                 dma_len = tx_queue->efx->type->tx_limit_len(tx_queue,
 125                                 dma_addr, len);
 126
 127                 /* If there's space for everything this is our last buffer. */
 128                 if (dma_len >= len)
 129                         break;
 130
 131                 buffer->len = dma_len;
 132                 buffer->flags = EFX_TX_BUF_CONT;
 133                 dma_addr += dma_len;
 134                 len -= dma_len;
 135         }
 136
 137         EFX_WARN_ON_ONCE_PARANOID(!len);
 138         buffer->len = len;
 139         *final_buffer = buffer;
 140 }
 141
 142 /*
 143  * Verify that our various assumptions about sk_buffs and the conditions
 144  * under which TSO will be attempted hold true.  Return the protocol number.
 145  */
 146 static __be16 efx_tso_check_protocol(struct sk_buff *skb)
 147 {
 148         __be16 protocol = skb->protocol;
 149
 150         EFX_WARN_ON_ONCE_PARANOID(((struct ethhdr *)skb->data)->h_proto !=
 151                                   protocol);
 152         if (protocol == htons(ETH_P_8021Q)) {
 153                 struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
 154
 155                 protocol = veh->h_vlan_encapsulated_proto;
 156         }
 157
 158         if (protocol == htons(ETH_P_IP)) {
 159                 EFX_WARN_ON_ONCE_PARANOID(ip_hdr(skb)->protocol != IPPROTO_TCP);
 160         } else {
 161                 EFX_WARN_ON_ONCE_PARANOID(protocol != htons(ETH_P_IPV6));
 162                 EFX_WARN_ON_ONCE_PARANOID(ipv6_hdr(skb)->nexthdr != NEXTHDR_TCP);
 163         }
 164         EFX_WARN_ON_ONCE_PARANOID((PTR_DIFF(tcp_hdr(skb), skb->data) +
 165                                    (tcp_hdr(skb)->doff << 2u)) >
 166                                   skb_headlen(skb));
 167
 168         return protocol;
 169 }
 170
 171 /* Parse the SKB header and initialise state. */
 172 static int tso_start(struct tso_state *st, struct efx_nic *efx,
 173                      struct efx_tx_queue *tx_queue,
 174                      const struct sk_buff *skb)
 175 {
 176         struct device *dma_dev = &efx->pci_dev->dev;
 177         unsigned int header_len, in_len;
 178         dma_addr_t dma_addr;
 179
 180         st->ip_off = skb_network_header(skb) - skb->data;
 181         st->tcp_off = skb_transport_header(skb) - skb->data;
 182         header_len = st->tcp_off + (tcp_hdr(skb)->doff << 2u);
 183         in_len = skb_headlen(skb) - header_len;
 184         st->header_len = header_len;
 185         st->in_len = in_len;
 186         if (st->protocol == htons(ETH_P_IP)) {
 187                 st->ip_base_len = st->header_len - st->ip_off;
 188                 st->ipv4_id = ntohs(ip_hdr(skb)->id);
 189         } else {
 190                 st->ip_base_len = st->header_len - st->tcp_off;
 191                 st->ipv4_id = 0;
 192         }
 193         st->seqnum = ntohl(tcp_hdr(skb)->seq);
 194
 195         EFX_WARN_ON_ONCE_PARANOID(tcp_hdr(skb)->urg);
 196         EFX_WARN_ON_ONCE_PARANOID(tcp_hdr(skb)->syn);
 197         EFX_WARN_ON_ONCE_PARANOID(tcp_hdr(skb)->rst);
 198
 199         st->out_len = skb->len - header_len;
 200
 201         dma_addr = dma_map_single(dma_dev, skb->data,
 202                                   skb_headlen(skb), DMA_TO_DEVICE);
 203         st->header_dma_addr = dma_addr;
 204         st->header_unmap_len = skb_headlen(skb);
 205         st->dma_addr = dma_addr + header_len;
 206         st->unmap_len = 0;
 207
 208         return unlikely(dma_mapping_error(dma_dev, dma_addr)) ? -ENOMEM : 0;
 209 }
 210
 211 static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
 212                             skb_frag_t *frag)
 213 {
 214         st->unmap_addr = skb_frag_dma_map(&efx->pci_dev->dev, frag, 0,
 215                                           skb_frag_size(frag), DMA_TO_DEVICE);
 216         if (likely(!dma_mapping_error(&efx->pci_dev->dev, st->unmap_addr))) {
 217                 st->unmap_len = skb_frag_size(frag);
 218                 st->in_len = skb_frag_size(frag);
 219                 st->dma_addr = st->unmap_addr;
 220                 return 0;
 221         }
 222         return -ENOMEM;
 223 }
 224
 225
 226 /**
 227  * tso_fill_packet_with_fragment - form descriptors for the current fragment
 228  * @tx_queue:           Efx TX queue
 229  * @skb:                Socket buffer
 230  * @st:                 TSO state
 231  *
 232  * Form descriptors for the current fragment, until we reach the end
 233  * of fragment or end-of-packet.
 234  */
 235 static void tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
 236                                           const struct sk_buff *skb,
 237                                           struct tso_state *st)
 238 {
 239         struct efx_tx_buffer *buffer;
 240         int n;
 241
 242         if (st->in_len == 0)
 243                 return;
 244         if (st->packet_space == 0)
 245                 return;
 246
 247         EFX_WARN_ON_ONCE_PARANOID(st->in_len <= 0);
 248         EFX_WARN_ON_ONCE_PARANOID(st->packet_space <= 0);
 249
 250         n = min(st->in_len, st->packet_space);
 251
 252         st->packet_space -= n;
 253         st->out_len -= n;
 254         st->in_len -= n;
 255
 256         efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer);
 257
 258         if (st->out_len == 0) {
 259                 /* Transfer ownership of the skb */
 260                 buffer->skb = skb;
 261                 buffer->flags = EFX_TX_BUF_SKB;
 262         } else if (st->packet_space != 0) {
 263                 buffer->flags = EFX_TX_BUF_CONT;
 264         }
 265
 266         if (st->in_len == 0) {
 267                 /* Transfer ownership of the DMA mapping */
 268                 buffer->unmap_len = st->unmap_len;
 269                 buffer->dma_offset = buffer->unmap_len - buffer->len;
 270                 st->unmap_len = 0;
 271         }
 272
 273         st->dma_addr += n;
 274 }
 275
 276
 277 #define TCP_FLAGS_OFFSET 13
 278
 279 /**
 280  * tso_start_new_packet - generate a new header and prepare for the new packet
 281  * @tx_queue:           Efx TX queue
 282  * @skb:                Socket buffer
 283  * @st:                 TSO state
 284  *
 285  * Generate a new header and prepare for the new packet.  Return 0 on
 286  * success, or -%ENOMEM if failed to alloc header, or other negative error.
 287  */
 288 static int tso_start_new_packet(struct efx_tx_queue *tx_queue,
 289                                 const struct sk_buff *skb,
 290                                 struct tso_state *st)
 291 {
 292         struct efx_tx_buffer *buffer =
 293                 efx_tx_queue_get_insert_buffer(tx_queue);
 294         bool is_last = st->out_len <= skb_shinfo(skb)->gso_size;
 295         u8 tcp_flags_mask, tcp_flags;
 296
 297         if (!is_last) {
 298                 st->packet_space = skb_shinfo(skb)->gso_size;
 299                 tcp_flags_mask = 0x09; /* mask out FIN and PSH */
 300         } else {
 301                 st->packet_space = st->out_len;
 302                 tcp_flags_mask = 0x00;
 303         }
 304
 305         if (WARN_ON(!st->header_unmap_len))
 306                 return -EINVAL;
 307         /* Send the original headers with a TSO option descriptor
 308          * in front
 309          */
 310         tcp_flags = ((u8 *)tcp_hdr(skb))[TCP_FLAGS_OFFSET] & ~tcp_flags_mask;
 311
 312         buffer->flags = EFX_TX_BUF_OPTION;
 313         buffer->len = 0;
 314         buffer->unmap_len = 0;
 315         EFX_POPULATE_QWORD_5(buffer->option,
 316                              ESF_DZ_TX_DESC_IS_OPT, 1,
 317                              ESF_DZ_TX_OPTION_TYPE,
 318                              ESE_DZ_TX_OPTION_DESC_TSO,
 319                              ESF_DZ_TX_TSO_TCP_FLAGS, tcp_flags,
 320                              ESF_DZ_TX_TSO_IP_ID, st->ipv4_id,
 321                              ESF_DZ_TX_TSO_TCP_SEQNO, st->seqnum);
 322         ++tx_queue->insert_count;
 323
 324         /* We mapped the headers in tso_start().  Unmap them
 325          * when the last segment is completed.
 326          */
 327         buffer = efx_tx_queue_get_insert_buffer(tx_queue);
 328         buffer->dma_addr = st->header_dma_addr;
 329         buffer->len = st->header_len;
 330         if (is_last) {
 331                 buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_MAP_SINGLE;
 332                 buffer->unmap_len = st->header_unmap_len;
 333                 buffer->dma_offset = 0;
 334                 /* Ensure we only unmap them once in case of a
 335                  * later DMA mapping error and rollback
 336                  */
 337                 st->header_unmap_len = 0;
 338         } else {
 339                 buffer->flags = EFX_TX_BUF_CONT;
 340                 buffer->unmap_len = 0;
 341         }
 342         ++tx_queue->insert_count;
 343
 344         st->seqnum += skb_shinfo(skb)->gso_size;
 345
 346         /* Linux leaves suitable gaps in the IP ID space for us to fill. */
 347         ++st->ipv4_id;
 348
 349         return 0;
 350 }
 351
 352 /**
 353  * efx_enqueue_skb_tso - segment and transmit a TSO socket buffer
 354  * @tx_queue:           Efx TX queue
 355  * @skb:                Socket buffer
 356  * @data_mapped:        Did we map the data? Always set to true
 357  *                      by this on success.
 358  *
 359  * Context: You must hold netif_tx_lock() to call this function.
 360  *
 361  * Add socket buffer @skb to @tx_queue, doing TSO or return != 0 if
 362  * @skb was not enqueued.  @skb is consumed unless return value is
 363  * %EINVAL.
 364  */
 365 int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
 366                         struct sk_buff *skb,
 367                         bool *data_mapped)
 368 {
 369         struct efx_nic *efx = tx_queue->efx;
 370         int frag_i, rc;
 371         struct tso_state state;
 372
 373         if (tx_queue->tso_version != 1)
 374                 return -EINVAL;
 375
 376         prefetch(skb->data);
 377
 378         /* Find the packet protocol and sanity-check it */
 379         state.protocol = efx_tso_check_protocol(skb);
 380
 381         EFX_WARN_ON_ONCE_PARANOID(tx_queue->write_count != tx_queue->insert_count);
 382
 383         rc = tso_start(&state, efx, tx_queue, skb);
 384         if (rc)
 385                 goto fail;
 386
 387         if (likely(state.in_len == 0)) {
 388                 /* Grab the first payload fragment. */
 389                 EFX_WARN_ON_ONCE_PARANOID(skb_shinfo(skb)->nr_frags < 1);
 390                 frag_i = 0;
 391                 rc = tso_get_fragment(&state, efx,
 392                                       skb_shinfo(skb)->frags + frag_i);
 393                 if (rc)
 394                         goto fail;
 395         } else {
 396                 /* Payload starts in the header area. */
 397                 frag_i = -1;
 398         }
 399
 400         rc = tso_start_new_packet(tx_queue, skb, &state);
 401         if (rc)
 402                 goto fail;
 403
 404         prefetch_ptr(tx_queue);
 405
 406         while (1) {
 407                 tso_fill_packet_with_fragment(tx_queue, skb, &state);
 408
 409                 /* Move onto the next fragment? */
 410                 if (state.in_len == 0) {
 411                         if (++frag_i >= skb_shinfo(skb)->nr_frags)
 412                                 /* End of payload reached. */
 413                                 break;
 414                         rc = tso_get_fragment(&state, efx,
 415                                               skb_shinfo(skb)->frags + frag_i);
 416                         if (rc)
 417                                 goto fail;
 418                 }
 419
 420                 /* Start at new packet? */
 421                 if (state.packet_space == 0) {
 422                         rc = tso_start_new_packet(tx_queue, skb, &state);
 423                         if (rc)
 424                                 goto fail;
 425                 }
 426         }
 427
 428         *data_mapped = true;
 429
 430         return 0;
 431
 432 fail:
 433         if (rc == -ENOMEM)
 434                 netif_err(efx, tx_err, efx->net_dev,
 435                           "Out of memory for TSO headers, or DMA mapping error\n");
 436         else
 437                 netif_err(efx, tx_err, efx->net_dev, "TSO failed, rc = %d\n", rc);
 438
 439         /* Free the DMA mapping we were in the process of writing out */
 440         if (state.unmap_len) {
 441                 dma_unmap_page(&efx->pci_dev->dev, state.unmap_addr,
 442                                state.unmap_len, DMA_TO_DEVICE);
 443         }
 444
 445         /* Free the header DMA mapping */
 446         if (state.header_unmap_len)
 447                 dma_unmap_single(&efx->pci_dev->dev, state.header_dma_addr,
 448                                  state.header_unmap_len, DMA_TO_DEVICE);
 449
 450         return rc;
 451 }