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 #include "qemu/main-loop.h"
  42
  43 typedef struct NetmapState {
  44     NetClientState      nc;
  45     struct nm_desc      *nmd;
  46     char                ifname[IFNAMSIZ];
  47     struct netmap_ring  *tx;
  48     struct netmap_ring  *rx;
  49     bool                read_poll;
  50     bool                write_poll;
  51     struct iovec        iov[IOV_MAX];
  52     int                 vnet_hdr_len;  /* Current virtio-net header length. */
  53 } NetmapState;
  54
  55 #ifndef __FreeBSD__
  56 #define pkt_copy bcopy
  57 #else
  58 /* A fast copy routine only for multiples of 64 bytes, non overlapped. */
  59 static inline void
  60 pkt_copy(const void *_src, void *_dst, int l)
  61 {
  62     const uint64_t *src = _src;
  63     uint64_t *dst = _dst;
  64     if (unlikely(l >= 1024)) {
  65         bcopy(src, dst, l);
  66         return;
  67     }
  68     for (; l > 0; l -= 64) {
  69         *dst++ = *src++;
  70         *dst++ = *src++;
  71         *dst++ = *src++;
  72         *dst++ = *src++;
  73         *dst++ = *src++;
  74         *dst++ = *src++;
  75         *dst++ = *src++;
  76         *dst++ = *src++;
  77     }
  78 }
  79 #endif /* __FreeBSD__ */
  80
  81 /*
  82  * Open a netmap device. We assume there is only one queue
  83  * (which is the case for the VALE bridge).
  84  */
  85 static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
  86                                    Error **errp)
  87 {
  88     struct nm_desc *nmd;
  89     struct nmreq req;
  90
  91     memset(&req, 0, sizeof(req));
  92
  93     nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
  94                   NULL);
  95     if (nmd == NULL) {
  96         error_setg_errno(errp, errno, "Failed to nm_open() %s",
  97                          nm_opts->ifname);
  98         return NULL;
  99     }
 100
 101     return nmd;
 102 }
 103
 104 static void netmap_send(void *opaque);
 105 static void netmap_writable(void *opaque);
 106
 107 /* Set the event-loop handlers for the netmap backend. */
 108 static void netmap_update_fd_handler(NetmapState *s)
 109 {
 110     qemu_set_fd_handler(s->nmd->fd,
 111                         s->read_poll ? netmap_send : NULL,
 112                         s->write_poll ? netmap_writable : NULL,
 113                         s);
 114 }
 115
 116 /* Update the read handler. */
 117 static void netmap_read_poll(NetmapState *s, bool enable)
 118 {
 119     if (s->read_poll != enable) { /* Do nothing if not changed. */
 120         s->read_poll = enable;
 121         netmap_update_fd_handler(s);
 122     }
 123 }
 124
 125 /* Update the write handler. */
 126 static void netmap_write_poll(NetmapState *s, bool enable)
 127 {
 128     if (s->write_poll != enable) {
 129         s->write_poll = enable;
 130         netmap_update_fd_handler(s);
 131     }
 132 }
 133
 134 static void netmap_poll(NetClientState *nc, bool enable)
 135 {
 136     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 137
 138     if (s->read_poll != enable || s->write_poll != enable) {
 139         s->write_poll = enable;
 140         s->read_poll  = enable;
 141         netmap_update_fd_handler(s);
 142     }
 143 }
 144
 145 /*
 146  * The fd_write() callback, invoked if the fd is marked as
 147  * writable after a poll. Unregister the handler and flush any
 148  * buffered packets.
 149  */
 150 static void netmap_writable(void *opaque)
 151 {
 152     NetmapState *s = opaque;
 153
 154     netmap_write_poll(s, false);
 155     qemu_flush_queued_packets(&s->nc);
 156 }
 157
 158 static ssize_t netmap_receive_iov(NetClientState *nc,
 159                     const struct iovec *iov, int iovcnt)
 160 {
 161     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 162     struct netmap_ring *ring = s->tx;
 163     unsigned int tail = ring->tail;
 164     ssize_t totlen = 0;
 165     uint32_t last;
 166     uint32_t idx;
 167     uint8_t *dst;
 168     int j;
 169     uint32_t i;
 170
 171     last = i = ring->head;
 172
 173     if (nm_ring_space(ring) < iovcnt) {
 174         /* Not enough netmap slots. Tell the kernel that we have seen the new
 175          * available slots (so that it notifies us again when it has more
 176          * ones), but without publishing any new slots to be processed
 177          * (e.g., we don't advance ring->head). */
 178         ring->cur = tail;
 179         netmap_write_poll(s, true);
 180         return 0;
 181     }
 182
 183     for (j = 0; j < iovcnt; j++) {
 184         int iov_frag_size = iov[j].iov_len;
 185         int offset = 0;
 186         int nm_frag_size;
 187
 188         totlen += iov_frag_size;
 189
 190         /* Split each iovec fragment over more netmap slots, if
 191            necessary. */
 192         while (iov_frag_size) {
 193             nm_frag_size = MIN(iov_frag_size, ring->nr_buf_size);
 194
 195             if (unlikely(i == tail)) {
 196                 /* We ran out of netmap slots while splitting the
 197                    iovec fragments. */
 198                 ring->cur = tail;
 199                 netmap_write_poll(s, true);
 200                 return 0;
 201             }
 202
 203             idx = ring->slot[i].buf_idx;
 204             dst = (uint8_t *)NETMAP_BUF(ring, idx);
 205
 206             ring->slot[i].len = nm_frag_size;
 207             ring->slot[i].flags = NS_MOREFRAG;
 208             pkt_copy(iov[j].iov_base + offset, dst, nm_frag_size);
 209
 210             last = i;
 211             i = nm_ring_next(ring, i);
 212
 213             offset += nm_frag_size;
 214             iov_frag_size -= nm_frag_size;
 215         }
 216     }
 217     /* The last slot must not have NS_MOREFRAG set. */
 218     ring->slot[last].flags &= ~NS_MOREFRAG;
 219
 220     /* Now update ring->head and ring->cur to publish the new slots and
 221      * the new wakeup point. */
 222     ring->head = ring->cur = i;
 223
 224     ioctl(s->nmd->fd, NIOCTXSYNC, NULL);
 225
 226     return totlen;
 227 }
 228
 229 static ssize_t netmap_receive(NetClientState *nc,
 230       const uint8_t *buf, size_t size)
 231 {
 232     struct iovec iov;
 233
 234     iov.iov_base = (void *)buf;
 235     iov.iov_len = size;
 236
 237     return netmap_receive_iov(nc, &iov, 1);
 238 }
 239
 240 /* Complete a previous send (backend --> guest) and enable the
 241    fd_read callback. */
 242 static void netmap_send_completed(NetClientState *nc, ssize_t len)
 243 {
 244     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 245
 246     netmap_read_poll(s, true);
 247 }
 248
 249 static void netmap_send(void *opaque)
 250 {
 251     NetmapState *s = opaque;
 252     struct netmap_ring *ring = s->rx;
 253     unsigned int tail = ring->tail;
 254
 255     /* Keep sending while there are available slots in the netmap
 256        RX ring and the forwarding path towards the peer is open. */
 257     while (ring->head != tail) {
 258         uint32_t i = ring->head;
 259         uint32_t idx;
 260         bool morefrag;
 261         int iovcnt = 0;
 262         int iovsize;
 263
 264         /* Get a (possibly multi-slot) packet. */
 265         do {
 266             idx = ring->slot[i].buf_idx;
 267             morefrag = (ring->slot[i].flags & NS_MOREFRAG);
 268             s->iov[iovcnt].iov_base = (void *)NETMAP_BUF(ring, idx);
 269             s->iov[iovcnt].iov_len = ring->slot[i].len;
 270             iovcnt++;
 271             i = nm_ring_next(ring, i);
 272         } while (i != tail && morefrag);
 273
 274         /* Advance ring->cur to tell the kernel that we have seen the slots. */
 275         ring->cur = i;
 276
 277         if (unlikely(morefrag)) {
 278             /* This is a truncated packet, so we can stop without releasing the
 279              * incomplete slots by updating ring->head. We will hopefully
 280              * re-read the complete packet the next time we are called. */
 281             break;
 282         }
 283
 284         iovsize = qemu_sendv_packet_async(&s->nc, s->iov, iovcnt,
 285                                             netmap_send_completed);
 286
 287         /* Release the slots to the kernel. */
 288         ring->head = i;
 289
 290         if (iovsize == 0) {
 291             /* The peer does not receive anymore. Packet is queued, stop
 292              * reading from the backend until netmap_send_completed(). */
 293             netmap_read_poll(s, false);
 294             break;
 295         }
 296     }
 297 }
 298
 299 /* Flush and close. */
 300 static void netmap_cleanup(NetClientState *nc)
 301 {
 302     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 303
 304     qemu_purge_queued_packets(nc);
 305
 306     netmap_poll(nc, false);
 307     nm_close(s->nmd);
 308     s->nmd = NULL;
 309 }
 310
 311 /* Offloading manipulation support callbacks. */
 312 static int netmap_fd_set_vnet_hdr_len(NetmapState *s, int len)
 313 {
 314     struct nmreq req;
 315
 316     /* Issue a NETMAP_BDG_VNET_HDR command to change the virtio-net header
 317      * length for the netmap adapter associated to 's->ifname'.
 318      */
 319     memset(&req, 0, sizeof(req));
 320     pstrcpy(req.nr_name, sizeof(req.nr_name), s->ifname);
 321     req.nr_version = NETMAP_API;
 322     req.nr_cmd = NETMAP_BDG_VNET_HDR;
 323     req.nr_arg1 = len;
 324
 325     return ioctl(s->nmd->fd, NIOCREGIF, &req);
 326 }
 327
 328 static bool netmap_has_vnet_hdr_len(NetClientState *nc, int len)
 329 {
 330     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 331     int prev_len = s->vnet_hdr_len;
 332
 333     /* Check that we can set the new length. */
 334     if (netmap_fd_set_vnet_hdr_len(s, len)) {
 335         return false;
 336     }
 337
 338     /* Restore the previous length. */
 339     if (netmap_fd_set_vnet_hdr_len(s, prev_len)) {
 340         error_report("Failed to restore vnet-hdr length %d on %s: %s",
 341                      prev_len, s->ifname, strerror(errno));
 342         abort();
 343     }
 344
 345     return true;
 346 }
 347
 348 /* A netmap interface that supports virtio-net headers always
 349  * supports UFO, so we use this callback also for the has_ufo hook. */
 350 static bool netmap_has_vnet_hdr(NetClientState *nc)
 351 {
 352     return netmap_has_vnet_hdr_len(nc, sizeof(struct virtio_net_hdr));
 353 }
 354
 355 static void netmap_using_vnet_hdr(NetClientState *nc, bool enable)
 356 {
 357 }
 358
 359 static void netmap_set_vnet_hdr_len(NetClientState *nc, int len)
 360 {
 361     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 362     int err;
 363
 364     err = netmap_fd_set_vnet_hdr_len(s, len);
 365     if (err) {
 366         error_report("Unable to set vnet-hdr length %d on %s: %s",
 367                      len, s->ifname, strerror(errno));
 368     } else {
 369         /* Keep track of the current length. */
 370         s->vnet_hdr_len = len;
 371     }
 372 }
 373
 374 static void netmap_set_offload(NetClientState *nc, int csum, int tso4, int tso6,
 375                                int ecn, int ufo)
 376 {
 377     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
 378
 379     /* Setting a virtio-net header length greater than zero automatically
 380      * enables the offloadings. */
 381     if (!s->vnet_hdr_len) {
 382         netmap_set_vnet_hdr_len(nc, sizeof(struct virtio_net_hdr));
 383     }
 384 }
 385
 386 /* NetClientInfo methods */
 387 static NetClientInfo net_netmap_info = {
 388     .type = NET_CLIENT_DRIVER_NETMAP,
 389     .size = sizeof(NetmapState),
 390     .receive = netmap_receive,
 391     .receive_iov = netmap_receive_iov,
 392     .poll = netmap_poll,
 393     .cleanup = netmap_cleanup,
 394     .has_ufo = netmap_has_vnet_hdr,
 395     .has_vnet_hdr = netmap_has_vnet_hdr,
 396     .has_vnet_hdr_len = netmap_has_vnet_hdr_len,
 397     .using_vnet_hdr = netmap_using_vnet_hdr,
 398     .set_offload = netmap_set_offload,
 399     .set_vnet_hdr_len = netmap_set_vnet_hdr_len,
 400 };
 401
 402 /* The exported init function
 403  *
 404  * ... -net netmap,ifname="..."
 405  */
 406 int net_init_netmap(const Netdev *netdev,
 407                     const char *name, NetClientState *peer, Error **errp)
 408 {
 409     const NetdevNetmapOptions *netmap_opts = &netdev->u.netmap;
 410     struct nm_desc *nmd;
 411     NetClientState *nc;
 412     Error *err = NULL;
 413     NetmapState *s;
 414
 415     nmd = netmap_open(netmap_opts, &err);
 416     if (err) {
 417         error_propagate(errp, err);
 418         return -1;
 419     }
 420     /* Create the object. */
 421     nc = qemu_new_net_client(&net_netmap_info, peer, "netmap", name);
 422     s = DO_UPCAST(NetmapState, nc, nc);
 423     s->nmd = nmd;
 424     s->tx = NETMAP_TXRING(nmd->nifp, 0);
 425     s->rx = NETMAP_RXRING(nmd->nifp, 0);
 426     s->vnet_hdr_len = 0;
 427     pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
 428     netmap_read_poll(s, true); /* Initially only poll for reads. */
 429
 430     return 0;
 431 }
 432