hw/virtio-net.c

   1 /*
   2  * Virtio Network Device
   3  *
   4  * Copyright IBM, Corp. 2007
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "virtio.h"
  15 #include "net.h"
  16 #include "pc.h"
  17 #include "qemu-timer.h"
  18
  19 /* from Linux's virtio_net.h */
  20
  21 /* The ID for virtio_net */
  22 #define VIRTIO_ID_NET   1
  23
  24 /* The feature bitmap for virtio net */
  25 #define VIRTIO_NET_F_NO_CSUM    0
  26 #define VIRTIO_NET_F_MAC        5
  27 #define VIRTIO_NET_F_GS0        6
  28
  29 #define TX_TIMER_INTERVAL (1000 / 500)
  30
  31 /* The config defining mac address (6 bytes) */
  32 struct virtio_net_config
  33 {
  34     uint8_t mac[6];
  35 } __attribute__((packed));
  36
  37 /* This is the first element of the scatter-gather list.  If you don't
  38  * specify GSO or CSUM features, you can simply ignore the header. */
  39 struct virtio_net_hdr
  40 {
  41 #define VIRTIO_NET_HDR_F_NEEDS_CSUM     1       // Use csum_start, csum_offset
  42     uint8_t flags;
  43 #define VIRTIO_NET_HDR_GSO_NONE         0       // Not a GSO frame
  44 #define VIRTIO_NET_HDR_GSO_TCPV4        1       // GSO frame, IPv4 TCP (TSO)
  45 /* FIXME: Do we need this?  If they said they can handle ECN, do they care? */
  46 #define VIRTIO_NET_HDR_GSO_TCPV4_ECN    2       // GSO frame, IPv4 TCP w/ ECN
  47 #define VIRTIO_NET_HDR_GSO_UDP          3       // GSO frame, IPv4 UDP (UFO)
  48 #define VIRTIO_NET_HDR_GSO_TCPV6        4       // GSO frame, IPv6 TCP
  49 #define VIRTIO_NET_HDR_GSO_ECN          0x80    // TCP has ECN set
  50     uint8_t gso_type;
  51     uint16_t hdr_len;
  52     uint16_t gso_size;
  53     uint16_t csum_start;
  54     uint16_t csum_offset;
  55 };
  56
  57 typedef struct VirtIONet
  58 {
  59     VirtIODevice vdev;
  60     uint8_t mac[6];
  61     VirtQueue *rx_vq;
  62     VirtQueue *tx_vq;
  63     VLANClientState *vc;
  64     int can_receive;
  65     int tap_fd;
  66     struct VirtIONet *next;
  67     int do_notify;
  68     QEMUTimer *tx_timer;
  69     int tx_timer_active;
  70 } VirtIONet;
  71
  72 static VirtIONet *VirtIONetHead = NULL;
  73
  74 static VirtIONet *to_virtio_net(VirtIODevice *vdev)
  75 {
  76     return (VirtIONet *)vdev;
  77 }
  78
  79 static void virtio_net_update_config(VirtIODevice *vdev, uint8_t *config)
  80 {
  81     VirtIONet *n = to_virtio_net(vdev);
  82     struct virtio_net_config netcfg;
  83
  84     memcpy(netcfg.mac, n->mac, 6);
  85     memcpy(config, &netcfg, sizeof(netcfg));
  86 }
  87
  88 static uint32_t virtio_net_get_features(VirtIODevice *vdev)
  89 {
  90     return (1 << VIRTIO_NET_F_MAC);
  91 }
  92
  93 /* RX */
  94
  95 static void virtio_net_handle_rx(VirtIODevice *vdev, VirtQueue *vq)
  96 {
  97     VirtIONet *n = to_virtio_net(vdev);
  98     n->can_receive = 1;
  99 }
 100
 101 static int virtio_net_can_receive(void *opaque)
 102 {
 103     VirtIONet *n = opaque;
 104
 105     return (n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) && n->can_receive;
 106 }
 107
 108 /* -net user receive function */
 109 static void virtio_net_receive(void *opaque, const uint8_t *buf, int size)
 110 {
 111     VirtIONet *n = opaque;
 112     VirtQueueElement elem;
 113     struct virtio_net_hdr *hdr;
 114     int offset, i;
 115
 116     /* FIXME: the drivers really need to set their status better */
 117     if (n->rx_vq->vring.avail == NULL) {
 118         n->can_receive = 0;
 119         return;
 120     }
 121
 122     if (virtqueue_pop(n->rx_vq, &elem) == 0) {
 123         /* wait until the guest adds some rx bufs */
 124         n->can_receive = 0;
 125         return;
 126     }
 127
 128     hdr = (void *)elem.in_sg[0].iov_base;
 129     hdr->flags = 0;
 130     hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 131
 132     /* copy in packet.  ugh */
 133     offset = 0;
 134     i = 1;
 135     while (offset < size && i < elem.in_num) {
 136         int len = MIN(elem.in_sg[i].iov_len, size - offset);
 137         memcpy(elem.in_sg[i].iov_base, buf + offset, len);
 138         offset += len;
 139         i++;
 140     }
 141
 142     /* signal other side */
 143     virtqueue_push(n->rx_vq, &elem, sizeof(*hdr) + offset);
 144     virtio_notify(&n->vdev, n->rx_vq);
 145 }
 146
 147 /* -net tap receive handler */
 148 void virtio_net_poll(void)
 149 {
 150     VirtIONet *vnet;
 151     int len;
 152     fd_set rfds;
 153     struct timeval tv;
 154     int max_fd = -1;
 155     VirtQueueElement elem;
 156     struct virtio_net_hdr *hdr;
 157     int did_notify;
 158
 159     FD_ZERO(&rfds);
 160     tv.tv_sec = 0;
 161     tv.tv_usec = 0;
 162
 163     while (1) {
 164
 165         // Prepare the set of device to select from
 166         for (vnet = VirtIONetHead; vnet; vnet = vnet->next) {
 167
 168             if (vnet->tap_fd == -1)
 169                 continue;
 170
 171             vnet->do_notify = 0;
 172             //first check if the driver is ok
 173             if (!virtio_net_can_receive(vnet))
 174                 continue;
 175
 176             /* FIXME: the drivers really need to set their status better */
 177             if (vnet->rx_vq->vring.avail == NULL) {
 178                 vnet->can_receive = 0;
 179                 continue;
 180             }
 181
 182             FD_SET(vnet->tap_fd, &rfds);
 183             if (max_fd < vnet->tap_fd) max_fd = vnet->tap_fd;
 184         }
 185
 186         if (select(max_fd + 1, &rfds, NULL, NULL, &tv) <= 0)
 187             break;
 188
 189         // Now check who has data pending in the tap
 190         for (vnet = VirtIONetHead; vnet; vnet = vnet->next) {
 191
 192             if (!FD_ISSET(vnet->tap_fd, &rfds))
 193                 continue;
 194
 195             if (virtqueue_pop(vnet->rx_vq, &elem) == 0) {
 196                 vnet->can_receive = 0;
 197                 continue;
 198             }
 199
 200             hdr = (void *)elem.in_sg[0].iov_base;
 201             hdr->flags = 0;
 202             hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 203 again:
 204             len = readv(vnet->tap_fd, &elem.in_sg[1], elem.in_num - 1);
 205             if (len == -1) {
 206                 if (errno == EINTR || errno == EAGAIN)
 207                     goto again;
 208                 else
 209                     fprintf(stderr, "reading network error %d", len);
 210             }
 211             virtqueue_push(vnet->rx_vq, &elem, sizeof(*hdr) + len);
 212             vnet->do_notify = 1;
 213         }
 214
 215         /* signal other side */
 216         did_notify = 0;
 217         for (vnet = VirtIONetHead; vnet; vnet = vnet->next)
 218             if (vnet->do_notify) {
 219                 virtio_notify(&vnet->vdev, vnet->rx_vq);
 220                 did_notify++;
 221             }
 222         if (!did_notify)
 223             break;
 224      }
 225
 226 }
 227
 228 /* TX */
 229 static void virtio_net_flush_tx(VirtIONet *n, VirtQueue *vq)
 230 {
 231     VirtQueueElement elem;
 232     int count = 0;
 233
 234     if (!(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK))
 235         return;
 236
 237     while (virtqueue_pop(vq, &elem)) {
 238         int i;
 239         size_t len = 0;
 240
 241         /* ignore the header for now */
 242         for (i = 1; i < elem.out_num; i++) {
 243             qemu_send_packet(n->vc, elem.out_sg[i].iov_base,
 244                              elem.out_sg[i].iov_len);
 245             len += elem.out_sg[i].iov_len;
 246         }
 247
 248         count++;
 249
 250         virtqueue_push(vq, &elem, sizeof(struct virtio_net_hdr) + len);
 251         virtio_notify(&n->vdev, vq);
 252     }
 253 }
 254
 255 static void virtio_net_handle_tx(VirtIODevice *vdev, VirtQueue *vq)
 256 {
 257     VirtIONet *n = to_virtio_net(vdev);
 258
 259     if (n->tx_timer_active &&
 260         (vq->vring.avail->idx - vq->last_avail_idx) == 64) {
 261         vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
 262         qemu_del_timer(n->tx_timer);
 263         n->tx_timer_active = 0;
 264         virtio_net_flush_tx(n, vq);
 265     } else {
 266         qemu_mod_timer(n->tx_timer,
 267                        qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);
 268         n->tx_timer_active = 1;
 269         vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
 270     }
 271 }
 272
 273 static void virtio_net_tx_timer(void *opaque)
 274 {
 275     VirtIONet *n = opaque;
 276
 277     n->tx_vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
 278     n->tx_timer_active = 0;
 279     virtio_net_flush_tx(n, n->tx_vq);
 280 }
 281
 282 void *virtio_net_init(PCIBus *bus, NICInfo *nd, int devfn)
 283 {
 284     VirtIONet *n;
 285
 286     n = (VirtIONet *)virtio_init_pci(bus, "virtio-net", 6900, 0x1000,
 287                                      0, VIRTIO_ID_NET,
 288                                      0x02, 0x00, 0x00,
 289                                      6, sizeof(VirtIONet));
 290
 291     n->vdev.update_config = virtio_net_update_config;
 292     n->vdev.get_features = virtio_net_get_features;
 293     n->rx_vq = virtio_add_queue(&n->vdev, 512, virtio_net_handle_rx);
 294     n->tx_vq = virtio_add_queue(&n->vdev, 128, virtio_net_handle_tx);
 295     n->can_receive = 0;
 296     memcpy(n->mac, nd->macaddr, 6);
 297     n->vc = qemu_new_vlan_client(nd->vlan, virtio_net_receive,
 298                                  virtio_net_can_receive, n);
 299     n->tap_fd = hack_around_tap(n->vc->vlan->first_client);
 300     if (n->tap_fd != -1) {
 301         n->next = VirtIONetHead;
 302         //push the device on top of the list
 303         VirtIONetHead = n;
 304     }
 305
 306     n->tx_timer = qemu_new_timer(vm_clock, virtio_net_tx_timer, n);
 307     n->tx_timer_active = 0;
 308
 309     return &n->vdev;
 310 }