net/netmap.c

   1 /*
   2  * netmap access for qemu
   3  *
   4  * Copyright (c) 2012-2013 Luigi Rizzo
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25
  26 #include "qemu/osdep.h"
  27 #include <sys/ioctl.h>
  28 #include <net/if.h>
  29 #define NETMAP_WITH_LIBS
  30 #include <net/netmap.h>
  31 #include <net/netmap_user.h>
  32
  33 #include "net/net.h"
  34 #include "net/tap.h"
  35 #include "clients.h"
  36 #include "sysemu/sysemu.h"
  37 #include "qemu/error-report.h"
  38 #include "qapi/error.h"
  39 #include "qemu/iov.h"
  40 #include "qemu/cutils.h"
  41
  42 typedef struct NetmapState {
  43     NetClientState      nc;
  44     struct nm_desc      *nmd;
  45     char                ifname[IFNAMSIZ];
  46     struct netmap_ring  *tx;
  47     struct netmap_ring  *rx;
  48     bool                read_poll;
  49     bool                write_poll;
  50     struct iovec        iov[IOV_MAX];
  51     int                 vnet_hdr_len;  /* Current virtio-net header length. */
  52 } NetmapState;
  53
  54 #ifndef __FreeBSD__
  55 #define pkt_copy bcopy
  56 #else
  57 /* A fast copy routine only for multiples of 64 bytes, non overlapped. */
  58 static inline void
  59 pkt_copy(const void *_src, void *_dst, int l)
  60 {
  61     const uint64_t *src = _src;
  62     uint64_t *dst = _dst;
  63     if (unlikely(l >= 1024)) {
  64         bcopy(src, dst, l);
  65         return;
  66     }
  67     for (; l > 0; l -= 64) {
  68         *dst++ = *src++;
  69         *dst++ = *src++;
  70         *dst++ = *src++;
  71         *dst++ = *src++;
  72         *dst++ = *src++;
  73         *dst++ = *src++;
  74         *dst++ = *src++;
  75         *dst++ = *src++;
  76     }
  77 }
  78 #endif /* __FreeBSD__ */
  79
  80 /*
  81  * Open a netmap device. We assume there is only one queue
  82  * (which is the case for the VALE bridge).
  83  */
  84 static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
  85                                    Error **errp)
  86 {
  87     struct nm_desc *nmd;
  88     struct nmreq req;
  89
  90     memset(&req, 0, sizeof(req));
  91
  92     nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
  93                   NULL);
  94     if (nmd == NULL) {
  95         error_setg_errno(errp, errno, "Failed to nm_open() %s",
  96                          nm_opts->ifname);
  97         return NULL;
  98     }
  99
 100     return nmd;
 101 }
 102
 103 static void netmap_send(void *opaque);
 104 static void netmap_writable(void *opaque);
 105
 106 /* Set the event-loop handlers for the netmap backend. */
 107 static void netmap_update_fd_handler(NetmapState *s)
 108 {
 109     qemu_set_fd_handler(s->nmd->fd,
 110                         s->read_poll ? netmap_send : NULL,
 111                         s->write_poll ? netmap_writable : NULL,
 112                         s);
 113 }
 114
 115 /* Update the read handler. */
 116 static void netmap_read_poll(NetmapState *s, bool enable)
 117 {
 118     if (s->read_poll != enable) { /* Do nothing if not changed. */
 119         s->read_poll = enable;
 120         netmap_update_fd_handler(s);
 121     }
 122 }
 123
 124 /* Update the write handler. */
 125 static void netmap_write_poll(NetmapState *s, bool enable)
 126 {
 127     if (s->write_poll != enable) {
 128         s->write_poll = enable;
 129         netmap_update_fd_handler(s);
 130     }
 131 }
 132
 133 static void netmap_poll(NetClientState *nc, bool enable)
 134 {
 135     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 136
 137     if (s->read_poll != enable || s->write_poll != enable) {
 138         s->write_poll = enable;
 139         s->read_poll  = enable;
 140         netmap_update_fd_handler(s);
 141     }
 142 }
 143
 144 /*
 145  * The fd_write() callback, invoked if the fd is marked as
 146  * writable after a poll. Unregister the handler and flush any
 147  * buffered packets.
 148  */
 149 static void netmap_writable(void *opaque)
 150 {
 151     NetmapState *s = opaque;
 152
 153     netmap_write_poll(s, false);
 154     qemu_flush_queued_packets(&s->nc);
 155 }
 156
 157 static ssize_t netmap_receive(NetClientState *nc,
 158       const uint8_t *buf, size_t size)
 159 {
 160     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 161     struct netmap_ring *ring = s->tx;
 162     uint32_t i;
 163     uint32_t idx;
 164     uint8_t *dst;
 165
 166     if (unlikely(!ring)) {
 167         /* Drop. */
 168         return size;
 169     }
 170
 171     if (unlikely(size > ring->nr_buf_size)) {
 172         RD(5, "[netmap_receive] drop packet of size %d > %d\n",
 173                                     (int)size, ring->nr_buf_size);
 174         return size;
 175     }
 176
 177     if (nm_ring_empty(ring)) {
 178         /* No available slots in the netmap TX ring. */
 179         netmap_write_poll(s, true);
 180         return 0;
 181     }
 182
 183     i = ring->cur;
 184     idx = ring->slot[i].buf_idx;
 185     dst = (uint8_t *)NETMAP_BUF(ring, idx);
 186
 187     ring->slot[i].len = size;
 188     ring->slot[i].flags = 0;
 189     pkt_copy(buf, dst, size);
 190     ring->cur = ring->head = nm_ring_next(ring, i);
 191     ioctl(s->nmd->fd, NIOCTXSYNC, NULL);
 192
 193     return size;
 194 }
 195
 196 static ssize_t netmap_receive_iov(NetClientState *nc,
 197                     const struct iovec *iov, int iovcnt)
 198 {
 199     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 200     struct netmap_ring *ring = s->tx;
 201     uint32_t last;
 202     uint32_t idx;
 203     uint8_t *dst;
 204     int j;
 205     uint32_t i;
 206
 207     if (unlikely(!ring)) {
 208         /* Drop the packet. */
 209         return iov_size(iov, iovcnt);
 210     }
 211
 212     last = i = ring->cur;
 213
 214     if (nm_ring_space(ring) < iovcnt) {
 215         /* Not enough netmap slots. */
 216         netmap_write_poll(s, true);
 217         return 0;
 218     }
 219
 220     for (j = 0; j < iovcnt; j++) {
 221         int iov_frag_size = iov[j].iov_len;
 222         int offset = 0;
 223         int nm_frag_size;
 224
 225         /* Split each iovec fragment over more netmap slots, if
 226            necessary. */
 227         while (iov_frag_size) {
 228             nm_frag_size = MIN(iov_frag_size, ring->nr_buf_size);
 229
 230             if (unlikely(nm_ring_empty(ring))) {
 231                 /* We run out of netmap slots while splitting the
 232                    iovec fragments. */
 233                 netmap_write_poll(s, true);
 234                 return 0;
 235             }
 236
 237             idx = ring->slot[i].buf_idx;
 238             dst = (uint8_t *)NETMAP_BUF(ring, idx);
 239
 240             ring->slot[i].len = nm_frag_size;
 241             ring->slot[i].flags = NS_MOREFRAG;
 242             pkt_copy(iov[j].iov_base + offset, dst, nm_frag_size);
 243
 244             last = i;
 245             i = nm_ring_next(ring, i);
 246
 247             offset += nm_frag_size;
 248             iov_frag_size -= nm_frag_size;
 249         }
 250     }
 251     /* The last slot must not have NS_MOREFRAG set. */
 252     ring->slot[last].flags &= ~NS_MOREFRAG;
 253
 254     /* Now update ring->cur and ring->head. */
 255     ring->cur = ring->head = i;
 256
 257     ioctl(s->nmd->fd, NIOCTXSYNC, NULL);
 258
 259     return iov_size(iov, iovcnt);
 260 }
 261
 262 /* Complete a previous send (backend --> guest) and enable the
 263    fd_read callback. */
 264 static void netmap_send_completed(NetClientState *nc, ssize_t len)
 265 {
 266     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 267
 268     netmap_read_poll(s, true);
 269 }
 270
 271 static void netmap_send(void *opaque)
 272 {
 273     NetmapState *s = opaque;
 274     struct netmap_ring *ring = s->rx;
 275
 276     /* Keep sending while there are available packets into the netmap
 277        RX ring and the forwarding path towards the peer is open. */
 278     while (!nm_ring_empty(ring)) {
 279         uint32_t i;
 280         uint32_t idx;
 281         bool morefrag;
 282         int iovcnt = 0;
 283         int iovsize;
 284
 285         do {
 286             i = ring->cur;
 287             idx = ring->slot[i].buf_idx;
 288             morefrag = (ring->slot[i].flags & NS_MOREFRAG);
 289             s->iov[iovcnt].iov_base = (u_char *)NETMAP_BUF(ring, idx);
 290             s->iov[iovcnt].iov_len = ring->slot[i].len;
 291             iovcnt++;
 292
 293             ring->cur = ring->head = nm_ring_next(ring, i);
 294         } while (!nm_ring_empty(ring) && morefrag);
 295
 296         if (unlikely(nm_ring_empty(ring) && morefrag)) {
 297             RD(5, "[netmap_send] ran out of slots, with a pending"
 298                    "incomplete packet\n");
 299         }
 300
 301         iovsize = qemu_sendv_packet_async(&s->nc, s->iov, iovcnt,
 302                                             netmap_send_completed);
 303
 304         if (iovsize == 0) {
 305             /* The peer does not receive anymore. Packet is queued, stop
 306              * reading from the backend until netmap_send_completed()
 307              */
 308             netmap_read_poll(s, false);
 309             break;
 310         }
 311     }
 312 }
 313
 314 /* Flush and close. */
 315 static void netmap_cleanup(NetClientState *nc)
 316 {
 317     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 318
 319     qemu_purge_queued_packets(nc);
 320
 321     netmap_poll(nc, false);
 322     nm_close(s->nmd);
 323     s->nmd = NULL;
 324 }
 325
 326 /* Offloading manipulation support callbacks. */
 327 static int netmap_fd_set_vnet_hdr_len(NetmapState *s, int len)
 328 {
 329     struct nmreq req;
 330
 331     /* Issue a NETMAP_BDG_VNET_HDR command to change the virtio-net header
 332      * length for the netmap adapter associated to 's->ifname'.
 333      */
 334     memset(&req, 0, sizeof(req));
 335     pstrcpy(req.nr_name, sizeof(req.nr_name), s->ifname);
 336     req.nr_version = NETMAP_API;
 337     req.nr_cmd = NETMAP_BDG_VNET_HDR;
 338     req.nr_arg1 = len;
 339
 340     return ioctl(s->nmd->fd, NIOCREGIF, &req);
 341 }
 342
 343 static bool netmap_has_vnet_hdr_len(NetClientState *nc, int len)
 344 {
 345     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 346     int prev_len = s->vnet_hdr_len;
 347
 348     /* Check that we can set the new length. */
 349     if (netmap_fd_set_vnet_hdr_len(s, len)) {
 350         return false;
 351     }
 352
 353     /* Restore the previous length. */
 354     if (netmap_fd_set_vnet_hdr_len(s, prev_len)) {
 355         error_report("Failed to restore vnet-hdr length %d on %s: %s",
 356                      prev_len, s->ifname, strerror(errno));
 357         abort();
 358     }
 359
 360     return true;
 361 }
 362
 363 /* A netmap interface that supports virtio-net headers always
 364  * supports UFO, so we use this callback also for the has_ufo hook. */
 365 static bool netmap_has_vnet_hdr(NetClientState *nc)
 366 {
 367     return netmap_has_vnet_hdr_len(nc, sizeof(struct virtio_net_hdr));
 368 }
 369
 370 static void netmap_using_vnet_hdr(NetClientState *nc, bool enable)
 371 {
 372 }
 373
 374 static void netmap_set_vnet_hdr_len(NetClientState *nc, int len)
 375 {
 376     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 377     int err;
 378
 379     err = netmap_fd_set_vnet_hdr_len(s, len);
 380     if (err) {
 381         error_report("Unable to set vnet-hdr length %d on %s: %s",
 382                      len, s->ifname, strerror(errno));
 383     } else {
 384         /* Keep track of the current length. */
 385         s->vnet_hdr_len = len;
 386     }
 387 }
 388
 389 static void netmap_set_offload(NetClientState *nc, int csum, int tso4, int tso6,
 390                                int ecn, int ufo)
 391 {
 392     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 393
 394     /* Setting a virtio-net header length greater than zero automatically
 395      * enables the offloadings. */
 396     if (!s->vnet_hdr_len) {
 397         netmap_set_vnet_hdr_len(nc, sizeof(struct virtio_net_hdr));
 398     }
 399 }
 400
 401 /* NetClientInfo methods */
 402 static NetClientInfo net_netmap_info = {
 403     .type = NET_CLIENT_DRIVER_NETMAP,
 404     .size = sizeof(NetmapState),
 405     .receive = netmap_receive,
 406     .receive_iov = netmap_receive_iov,
 407     .poll = netmap_poll,
 408     .cleanup = netmap_cleanup,
 409     .has_ufo = netmap_has_vnet_hdr,
 410     .has_vnet_hdr = netmap_has_vnet_hdr,
 411     .has_vnet_hdr_len = netmap_has_vnet_hdr_len,
 412     .using_vnet_hdr = netmap_using_vnet_hdr,
 413     .set_offload = netmap_set_offload,
 414     .set_vnet_hdr_len = netmap_set_vnet_hdr_len,
 415 };
 416
 417 /* The exported init function
 418  *
 419  * ... -net netmap,ifname="..."
 420  */
 421 int net_init_netmap(const Netdev *netdev,
 422                     const char *name, NetClientState *peer, Error **errp)
 423 {
 424     const NetdevNetmapOptions *netmap_opts = &netdev->u.netmap;
 425     struct nm_desc *nmd;
 426     NetClientState *nc;
 427     Error *err = NULL;
 428     NetmapState *s;
 429
 430     nmd = netmap_open(netmap_opts, &err);
 431     if (err) {
 432         error_propagate(errp, err);
 433         return -1;
 434     }
 435     /* Create the object. */
 436     nc = qemu_new_net_client(&net_netmap_info, peer, "netmap", name);
 437     s = DO_UPCAST(NetmapState, nc, nc);
 438     s->nmd = nmd;
 439     s->tx = NETMAP_TXRING(nmd->nifp, 0);
 440     s->rx = NETMAP_RXRING(nmd->nifp, 0);
 441     s->vnet_hdr_len = 0;
 442     pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
 443     netmap_read_poll(s, true); /* Initially only poll for reads. */
 444
 445     return 0;
 446 }
 447