hw/char/virtio-serial-bus.c

   1 /*
   2  * A bus for connecting virtio serial and console ports
   3  *
   4  * Copyright (C) 2009, 2010 Red Hat, Inc.
   5  *
   6  * Author(s):
   7  *  Amit Shah <amit.shah@redhat.com>
   8  *
   9  * Some earlier parts are:
  10  *  Copyright IBM, Corp. 2008
  11  * authored by
  12  *  Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
  13  *
  14  * This work is licensed under the terms of the GNU GPL, version 2.  See
  15  * the COPYING file in the top-level directory.
  16  *
  17  * Contributions after 2012-01-13 are licensed under the terms of the
  18  * GNU GPL, version 2 or (at your option) any later version.
  19  */
  20
  21 #include "qemu/osdep.h"
  22 #include "qemu/iov.h"
  23 #include "monitor/monitor.h"
  24 #include "qemu/error-report.h"
  25 #include "qemu/queue.h"
  26 #include "hw/sysbus.h"
  27 #include "trace.h"
  28 #include "hw/virtio/virtio-serial.h"
  29 #include "hw/virtio/virtio-access.h"
  30
  31 static struct VirtIOSerialDevices {
  32     QLIST_HEAD(, VirtIOSerial) devices;
  33 } vserdevices;
  34
  35 static VirtIOSerialPort *find_port_by_id(VirtIOSerial *vser, uint32_t id)
  36 {
  37     VirtIOSerialPort *port;
  38
  39     if (id == VIRTIO_CONSOLE_BAD_ID) {
  40         return NULL;
  41     }
  42
  43     QTAILQ_FOREACH(port, &vser->ports, next) {
  44         if (port->id == id)
  45             return port;
  46     }
  47     return NULL;
  48 }
  49
  50 static VirtIOSerialPort *find_port_by_vq(VirtIOSerial *vser, VirtQueue *vq)
  51 {
  52     VirtIOSerialPort *port;
  53
  54     QTAILQ_FOREACH(port, &vser->ports, next) {
  55         if (port->ivq == vq || port->ovq == vq)
  56             return port;
  57     }
  58     return NULL;
  59 }
  60
  61 static VirtIOSerialPort *find_port_by_name(char *name)
  62 {
  63     VirtIOSerial *vser;
  64
  65     QLIST_FOREACH(vser, &vserdevices.devices, next) {
  66         VirtIOSerialPort *port;
  67
  68         QTAILQ_FOREACH(port, &vser->ports, next) {
  69             if (port->name && !strcmp(port->name, name)) {
  70                 return port;
  71             }
  72         }
  73     }
  74     return NULL;
  75 }
  76
  77 static bool use_multiport(VirtIOSerial *vser)
  78 {
  79     VirtIODevice *vdev = VIRTIO_DEVICE(vser);
  80     return virtio_vdev_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT);
  81 }
  82
  83 static size_t write_to_port(VirtIOSerialPort *port,
  84                             const uint8_t *buf, size_t size)
  85 {
  86     VirtQueueElement elem;
  87     VirtQueue *vq;
  88     size_t offset;
  89
  90     vq = port->ivq;
  91     if (!virtio_queue_ready(vq)) {
  92         return 0;
  93     }
  94
  95     offset = 0;
  96     while (offset < size) {
  97         size_t len;
  98
  99         if (!virtqueue_pop(vq, &elem)) {
 100             break;
 101         }
 102
 103         len = iov_from_buf(elem.in_sg, elem.in_num, 0,
 104                            buf + offset, size - offset);
 105         offset += len;
 106
 107         virtqueue_push(vq, &elem, len);
 108     }
 109
 110     virtio_notify(VIRTIO_DEVICE(port->vser), vq);
 111     return offset;
 112 }
 113
 114 static void discard_vq_data(VirtQueue *vq, VirtIODevice *vdev)
 115 {
 116     VirtQueueElement elem;
 117
 118     if (!virtio_queue_ready(vq)) {
 119         return;
 120     }
 121     while (virtqueue_pop(vq, &elem)) {
 122         virtqueue_push(vq, &elem, 0);
 123     }
 124     virtio_notify(vdev, vq);
 125 }
 126
 127 static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq,
 128                                  VirtIODevice *vdev)
 129 {
 130     VirtIOSerialPortClass *vsc;
 131
 132     assert(port);
 133     assert(virtio_queue_ready(vq));
 134
 135     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 136
 137     while (!port->throttled) {
 138         unsigned int i;
 139
 140         /* Pop an elem only if we haven't left off a previous one mid-way */
 141         if (!port->elem.out_num) {
 142             if (!virtqueue_pop(vq, &port->elem)) {
 143                 break;
 144             }
 145             port->iov_idx = 0;
 146             port->iov_offset = 0;
 147         }
 148
 149         for (i = port->iov_idx; i < port->elem.out_num; i++) {
 150             size_t buf_size;
 151             ssize_t ret;
 152
 153             buf_size = port->elem.out_sg[i].iov_len - port->iov_offset;
 154             ret = vsc->have_data(port,
 155                                   port->elem.out_sg[i].iov_base
 156                                   + port->iov_offset,
 157                                   buf_size);
 158             if (port->throttled) {
 159                 port->iov_idx = i;
 160                 if (ret > 0) {
 161                     port->iov_offset += ret;
 162                 }
 163                 break;
 164             }
 165             port->iov_offset = 0;
 166         }
 167         if (port->throttled) {
 168             break;
 169         }
 170         virtqueue_push(vq, &port->elem, 0);
 171         port->elem.out_num = 0;
 172     }
 173     virtio_notify(vdev, vq);
 174 }
 175
 176 static void flush_queued_data(VirtIOSerialPort *port)
 177 {
 178     assert(port);
 179
 180     if (!virtio_queue_ready(port->ovq)) {
 181         return;
 182     }
 183     do_flush_queued_data(port, port->ovq, VIRTIO_DEVICE(port->vser));
 184 }
 185
 186 static size_t send_control_msg(VirtIOSerial *vser, void *buf, size_t len)
 187 {
 188     VirtQueueElement elem;
 189     VirtQueue *vq;
 190
 191     vq = vser->c_ivq;
 192     if (!virtio_queue_ready(vq)) {
 193         return 0;
 194     }
 195     if (!virtqueue_pop(vq, &elem)) {
 196         return 0;
 197     }
 198
 199     /* TODO: detect a buffer that's too short, set NEEDS_RESET */
 200     iov_from_buf(elem.in_sg, elem.in_num, 0, buf, len);
 201
 202     virtqueue_push(vq, &elem, len);
 203     virtio_notify(VIRTIO_DEVICE(vser), vq);
 204     return len;
 205 }
 206
 207 static size_t send_control_event(VirtIOSerial *vser, uint32_t port_id,
 208                                  uint16_t event, uint16_t value)
 209 {
 210     VirtIODevice *vdev = VIRTIO_DEVICE(vser);
 211     struct virtio_console_control cpkt;
 212
 213     virtio_stl_p(vdev, &cpkt.id, port_id);
 214     virtio_stw_p(vdev, &cpkt.event, event);
 215     virtio_stw_p(vdev, &cpkt.value, value);
 216
 217     trace_virtio_serial_send_control_event(port_id, event, value);
 218     return send_control_msg(vser, &cpkt, sizeof(cpkt));
 219 }
 220
 221 /* Functions for use inside qemu to open and read from/write to ports */
 222 int virtio_serial_open(VirtIOSerialPort *port)
 223 {
 224     /* Don't allow opening an already-open port */
 225     if (port->host_connected) {
 226         return 0;
 227     }
 228     /* Send port open notification to the guest */
 229     port->host_connected = true;
 230     send_control_event(port->vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 1);
 231
 232     return 0;
 233 }
 234
 235 int virtio_serial_close(VirtIOSerialPort *port)
 236 {
 237     port->host_connected = false;
 238     /*
 239      * If there's any data the guest sent which the app didn't
 240      * consume, reset the throttling flag and discard the data.
 241      */
 242     port->throttled = false;
 243     discard_vq_data(port->ovq, VIRTIO_DEVICE(port->vser));
 244
 245     send_control_event(port->vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 0);
 246
 247     return 0;
 248 }
 249
 250 /* Individual ports/apps call this function to write to the guest. */
 251 ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
 252                             size_t size)
 253 {
 254     if (!port || !port->host_connected || !port->guest_connected) {
 255         return 0;
 256     }
 257     return write_to_port(port, buf, size);
 258 }
 259
 260 /*
 261  * Readiness of the guest to accept data on a port.
 262  * Returns max. data the guest can receive
 263  */
 264 size_t virtio_serial_guest_ready(VirtIOSerialPort *port)
 265 {
 266     VirtIODevice *vdev = VIRTIO_DEVICE(port->vser);
 267     VirtQueue *vq = port->ivq;
 268     unsigned int bytes;
 269
 270     if (!virtio_queue_ready(vq) ||
 271         !(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) ||
 272         virtio_queue_empty(vq)) {
 273         return 0;
 274     }
 275     if (use_multiport(port->vser) && !port->guest_connected) {
 276         return 0;
 277     }
 278     virtqueue_get_avail_bytes(vq, &bytes, NULL, 4096, 0);
 279     return bytes;
 280 }
 281
 282 static void flush_queued_data_bh(void *opaque)
 283 {
 284     VirtIOSerialPort *port = opaque;
 285
 286     flush_queued_data(port);
 287 }
 288
 289 void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle)
 290 {
 291     if (!port) {
 292         return;
 293     }
 294
 295     trace_virtio_serial_throttle_port(port->id, throttle);
 296     port->throttled = throttle;
 297     if (throttle) {
 298         return;
 299     }
 300     qemu_bh_schedule(port->bh);
 301 }
 302
 303 /* Guest wants to notify us of some event */
 304 static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len)
 305 {
 306     VirtIODevice *vdev = VIRTIO_DEVICE(vser);
 307     struct VirtIOSerialPort *port;
 308     VirtIOSerialPortClass *vsc;
 309     struct virtio_console_control cpkt, *gcpkt;
 310     uint8_t *buffer;
 311     size_t buffer_len;
 312
 313     gcpkt = buf;
 314
 315     if (len < sizeof(cpkt)) {
 316         /* The guest sent an invalid control packet */
 317         return;
 318     }
 319
 320     cpkt.event = virtio_lduw_p(vdev, &gcpkt->event);
 321     cpkt.value = virtio_lduw_p(vdev, &gcpkt->value);
 322
 323     trace_virtio_serial_handle_control_message(cpkt.event, cpkt.value);
 324
 325     if (cpkt.event == VIRTIO_CONSOLE_DEVICE_READY) {
 326         if (!cpkt.value) {
 327             error_report("virtio-serial-bus: Guest failure in adding device %s",
 328                          vser->bus.qbus.name);
 329             return;
 330         }
 331         /*
 332          * The device is up, we can now tell the device about all the
 333          * ports we have here.
 334          */
 335         QTAILQ_FOREACH(port, &vser->ports, next) {
 336             send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_ADD, 1);
 337         }
 338         return;
 339     }
 340
 341     port = find_port_by_id(vser, virtio_ldl_p(vdev, &gcpkt->id));
 342     if (!port) {
 343         error_report("virtio-serial-bus: Unexpected port id %u for device %s",
 344                      virtio_ldl_p(vdev, &gcpkt->id), vser->bus.qbus.name);
 345         return;
 346     }
 347
 348     trace_virtio_serial_handle_control_message_port(port->id);
 349
 350     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 351
 352     switch(cpkt.event) {
 353     case VIRTIO_CONSOLE_PORT_READY:
 354         if (!cpkt.value) {
 355             error_report("virtio-serial-bus: Guest failure in adding port %u for device %s",
 356                          port->id, vser->bus.qbus.name);
 357             break;
 358         }
 359         /*
 360          * Now that we know the guest asked for the port name, we're
 361          * sure the guest has initialised whatever state is necessary
 362          * for this port. Now's a good time to let the guest know if
 363          * this port is a console port so that the guest can hook it
 364          * up to hvc.
 365          */
 366         if (vsc->is_console) {
 367             send_control_event(vser, port->id, VIRTIO_CONSOLE_CONSOLE_PORT, 1);
 368         }
 369
 370         if (port->name) {
 371             virtio_stl_p(vdev, &cpkt.id, port->id);
 372             virtio_stw_p(vdev, &cpkt.event, VIRTIO_CONSOLE_PORT_NAME);
 373             virtio_stw_p(vdev, &cpkt.value, 1);
 374
 375             buffer_len = sizeof(cpkt) + strlen(port->name) + 1;
 376             buffer = g_malloc(buffer_len);
 377
 378             memcpy(buffer, &cpkt, sizeof(cpkt));
 379             memcpy(buffer + sizeof(cpkt), port->name, strlen(port->name));
 380             buffer[buffer_len - 1] = 0;
 381
 382             send_control_msg(vser, buffer, buffer_len);
 383             g_free(buffer);
 384         }
 385
 386         if (port->host_connected) {
 387             send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 1);
 388         }
 389
 390         /*
 391          * When the guest has asked us for this information it means
 392          * the guest is all setup and has its virtqueues
 393          * initialised. If some app is interested in knowing about
 394          * this event, let it know.
 395          */
 396         if (vsc->guest_ready) {
 397             vsc->guest_ready(port);
 398         }
 399         break;
 400
 401     case VIRTIO_CONSOLE_PORT_OPEN:
 402         port->guest_connected = cpkt.value;
 403         if (vsc->set_guest_connected) {
 404             /* Send the guest opened notification if an app is interested */
 405             vsc->set_guest_connected(port, cpkt.value);
 406         }
 407         break;
 408     }
 409 }
 410
 411 static void control_in(VirtIODevice *vdev, VirtQueue *vq)
 412 {
 413 }
 414
 415 static void control_out(VirtIODevice *vdev, VirtQueue *vq)
 416 {
 417     VirtQueueElement elem;
 418     VirtIOSerial *vser;
 419     uint8_t *buf;
 420     size_t len;
 421
 422     vser = VIRTIO_SERIAL(vdev);
 423
 424     len = 0;
 425     buf = NULL;
 426     while (virtqueue_pop(vq, &elem)) {
 427         size_t cur_len;
 428
 429         cur_len = iov_size(elem.out_sg, elem.out_num);
 430         /*
 431          * Allocate a new buf only if we didn't have one previously or
 432          * if the size of the buf differs
 433          */
 434         if (cur_len > len) {
 435             g_free(buf);
 436
 437             buf = g_malloc(cur_len);
 438             len = cur_len;
 439         }
 440         iov_to_buf(elem.out_sg, elem.out_num, 0, buf, cur_len);
 441
 442         handle_control_message(vser, buf, cur_len);
 443         virtqueue_push(vq, &elem, 0);
 444     }
 445     g_free(buf);
 446     virtio_notify(vdev, vq);
 447 }
 448
 449 /* Guest wrote something to some port. */
 450 static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
 451 {
 452     VirtIOSerial *vser;
 453     VirtIOSerialPort *port;
 454
 455     vser = VIRTIO_SERIAL(vdev);
 456     port = find_port_by_vq(vser, vq);
 457
 458     if (!port || !port->host_connected) {
 459         discard_vq_data(vq, vdev);
 460         return;
 461     }
 462
 463     if (!port->throttled) {
 464         do_flush_queued_data(port, vq, vdev);
 465         return;
 466     }
 467 }
 468
 469 static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
 470 {
 471     /*
 472      * Users of virtio-serial would like to know when guest becomes
 473      * writable again -- i.e. if a vq had stuff queued up and the
 474      * guest wasn't reading at all, the host would not be able to
 475      * write to the vq anymore.  Once the guest reads off something,
 476      * we can start queueing things up again.  However, this call is
 477      * made for each buffer addition by the guest -- even though free
 478      * buffers existed prior to the current buffer addition.  This is
 479      * done so as not to maintain previous state, which will need
 480      * additional live-migration-related changes.
 481      */
 482     VirtIOSerial *vser;
 483     VirtIOSerialPort *port;
 484     VirtIOSerialPortClass *vsc;
 485
 486     vser = VIRTIO_SERIAL(vdev);
 487     port = find_port_by_vq(vser, vq);
 488
 489     if (!port) {
 490         return;
 491     }
 492     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 493
 494     /*
 495      * If guest_connected is false, this call is being made by the
 496      * early-boot queueing up of descriptors, which is just noise for
 497      * the host apps -- don't disturb them in that case.
 498      */
 499     if (port->guest_connected && port->host_connected && vsc->guest_writable) {
 500         vsc->guest_writable(port);
 501     }
 502 }
 503
 504 static uint64_t get_features(VirtIODevice *vdev, uint64_t features,
 505                              Error **errp)
 506 {
 507     VirtIOSerial *vser;
 508
 509     vser = VIRTIO_SERIAL(vdev);
 510
 511     if (vser->bus.max_nr_ports > 1) {
 512         virtio_add_feature(&features, VIRTIO_CONSOLE_F_MULTIPORT);
 513     }
 514     return features;
 515 }
 516
 517 /* Guest requested config info */
 518 static void get_config(VirtIODevice *vdev, uint8_t *config_data)
 519 {
 520     VirtIOSerial *vser = VIRTIO_SERIAL(vdev);
 521     struct virtio_console_config *config =
 522         (struct virtio_console_config *)config_data;
 523
 524     config->cols = 0;
 525     config->rows = 0;
 526     config->max_nr_ports = virtio_tswap32(vdev,
 527                                           vser->serial.max_virtserial_ports);
 528 }
 529
 530 static void guest_reset(VirtIOSerial *vser)
 531 {
 532     VirtIOSerialPort *port;
 533     VirtIOSerialPortClass *vsc;
 534
 535     QTAILQ_FOREACH(port, &vser->ports, next) {
 536         vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 537         if (port->guest_connected) {
 538             port->guest_connected = false;
 539             if (vsc->set_guest_connected) {
 540                 vsc->set_guest_connected(port, false);
 541             }
 542         }
 543     }
 544 }
 545
 546 static void set_status(VirtIODevice *vdev, uint8_t status)
 547 {
 548     VirtIOSerial *vser;
 549     VirtIOSerialPort *port;
 550
 551     vser = VIRTIO_SERIAL(vdev);
 552     port = find_port_by_id(vser, 0);
 553
 554     if (port && !use_multiport(port->vser)
 555         && (status & VIRTIO_CONFIG_S_DRIVER_OK)) {
 556         /*
 557          * Non-multiport guests won't be able to tell us guest
 558          * open/close status.  Such guests can only have a port at id
 559          * 0, so set guest_connected for such ports as soon as guest
 560          * is up.
 561          */
 562         port->guest_connected = true;
 563     }
 564     if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
 565         guest_reset(vser);
 566     }
 567 }
 568
 569 static void vser_reset(VirtIODevice *vdev)
 570 {
 571     VirtIOSerial *vser;
 572
 573     vser = VIRTIO_SERIAL(vdev);
 574     guest_reset(vser);
 575 }
 576
 577 static void virtio_serial_save(QEMUFile *f, void *opaque)
 578 {
 579     /* The virtio device */
 580     virtio_save(VIRTIO_DEVICE(opaque), f);
 581 }
 582
 583 static void virtio_serial_save_device(VirtIODevice *vdev, QEMUFile *f)
 584 {
 585     VirtIOSerial *s = VIRTIO_SERIAL(vdev);
 586     VirtIOSerialPort *port;
 587     uint32_t nr_active_ports;
 588     unsigned int i, max_nr_ports;
 589     struct virtio_console_config config;
 590
 591     /* The config space (ignored on the far end in current versions) */
 592     get_config(vdev, (uint8_t *)&config);
 593     qemu_put_be16s(f, &config.cols);
 594     qemu_put_be16s(f, &config.rows);
 595     qemu_put_be32s(f, &config.max_nr_ports);
 596
 597     /* The ports map */
 598     max_nr_ports = s->serial.max_virtserial_ports;
 599     for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
 600         qemu_put_be32s(f, &s->ports_map[i]);
 601     }
 602
 603     /* Ports */
 604
 605     nr_active_ports = 0;
 606     QTAILQ_FOREACH(port, &s->ports, next) {
 607         nr_active_ports++;
 608     }
 609
 610     qemu_put_be32s(f, &nr_active_ports);
 611
 612     /*
 613      * Items in struct VirtIOSerialPort.
 614      */
 615     QTAILQ_FOREACH(port, &s->ports, next) {
 616         uint32_t elem_popped;
 617
 618         qemu_put_be32s(f, &port->id);
 619         qemu_put_byte(f, port->guest_connected);
 620         qemu_put_byte(f, port->host_connected);
 621
 622         elem_popped = 0;
 623         if (port->elem.out_num) {
 624             elem_popped = 1;
 625         }
 626         qemu_put_be32s(f, &elem_popped);
 627         if (elem_popped) {
 628             qemu_put_be32s(f, &port->iov_idx);
 629             qemu_put_be64s(f, &port->iov_offset);
 630
 631             qemu_put_buffer(f, (unsigned char *)&port->elem,
 632                             sizeof(port->elem));
 633         }
 634     }
 635 }
 636
 637 static void virtio_serial_post_load_timer_cb(void *opaque)
 638 {
 639     uint32_t i;
 640     VirtIOSerial *s = VIRTIO_SERIAL(opaque);
 641     VirtIOSerialPort *port;
 642     uint8_t host_connected;
 643     VirtIOSerialPortClass *vsc;
 644
 645     if (!s->post_load) {
 646         return;
 647     }
 648     for (i = 0 ; i < s->post_load->nr_active_ports; ++i) {
 649         port = s->post_load->connected[i].port;
 650         host_connected = s->post_load->connected[i].host_connected;
 651         if (host_connected != port->host_connected) {
 652             /*
 653              * We have to let the guest know of the host connection
 654              * status change
 655              */
 656             send_control_event(s, port->id, VIRTIO_CONSOLE_PORT_OPEN,
 657                                port->host_connected);
 658         }
 659         vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 660         if (vsc->set_guest_connected) {
 661             vsc->set_guest_connected(port, port->guest_connected);
 662         }
 663     }
 664     g_free(s->post_load->connected);
 665     timer_free(s->post_load->timer);
 666     g_free(s->post_load);
 667     s->post_load = NULL;
 668 }
 669
 670 static int fetch_active_ports_list(QEMUFile *f, int version_id,
 671                                    VirtIOSerial *s, uint32_t nr_active_ports)
 672 {
 673     uint32_t i;
 674
 675     s->post_load = g_malloc0(sizeof(*s->post_load));
 676     s->post_load->nr_active_ports = nr_active_ports;
 677     s->post_load->connected =
 678         g_malloc0(sizeof(*s->post_load->connected) * nr_active_ports);
 679
 680     s->post_load->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
 681                                             virtio_serial_post_load_timer_cb,
 682                                             s);
 683
 684     /* Items in struct VirtIOSerialPort */
 685     for (i = 0; i < nr_active_ports; i++) {
 686         VirtIOSerialPort *port;
 687         uint32_t id;
 688
 689         id = qemu_get_be32(f);
 690         port = find_port_by_id(s, id);
 691         if (!port) {
 692             return -EINVAL;
 693         }
 694
 695         port->guest_connected = qemu_get_byte(f);
 696         s->post_load->connected[i].port = port;
 697         s->post_load->connected[i].host_connected = qemu_get_byte(f);
 698
 699         if (version_id > 2) {
 700             uint32_t elem_popped;
 701
 702             qemu_get_be32s(f, &elem_popped);
 703             if (elem_popped) {
 704                 qemu_get_be32s(f, &port->iov_idx);
 705                 qemu_get_be64s(f, &port->iov_offset);
 706
 707                 qemu_get_buffer(f, (unsigned char *)&port->elem,
 708                                 sizeof(port->elem));
 709                 virtqueue_map(&port->elem);
 710
 711                 /*
 712                  *  Port was throttled on source machine.  Let's
 713                  *  unthrottle it here so data starts flowing again.
 714                  */
 715                 virtio_serial_throttle_port(port, false);
 716             }
 717         }
 718     }
 719     timer_mod(s->post_load->timer, 1);
 720     return 0;
 721 }
 722
 723 static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
 724 {
 725     if (version_id > 3) {
 726         return -EINVAL;
 727     }
 728
 729     /* The virtio device */
 730     return virtio_load(VIRTIO_DEVICE(opaque), f, version_id);
 731 }
 732
 733 static int virtio_serial_load_device(VirtIODevice *vdev, QEMUFile *f,
 734                                      int version_id)
 735 {
 736     VirtIOSerial *s = VIRTIO_SERIAL(vdev);
 737     uint32_t max_nr_ports, nr_active_ports, ports_map;
 738     unsigned int i;
 739     int ret;
 740     uint32_t tmp;
 741
 742     if (version_id < 2) {
 743         return 0;
 744     }
 745
 746     /* Unused */
 747     qemu_get_be16s(f, (uint16_t *) &tmp);
 748     qemu_get_be16s(f, (uint16_t *) &tmp);
 749     qemu_get_be32s(f, &tmp);
 750
 751     max_nr_ports = s->serial.max_virtserial_ports;
 752     for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
 753         qemu_get_be32s(f, &ports_map);
 754
 755         if (ports_map != s->ports_map[i]) {
 756             /*
 757              * Ports active on source and destination don't
 758              * match. Fail migration.
 759              */
 760             return -EINVAL;
 761         }
 762     }
 763
 764     qemu_get_be32s(f, &nr_active_ports);
 765
 766     if (nr_active_ports) {
 767         ret = fetch_active_ports_list(f, version_id, s, nr_active_ports);
 768         if (ret) {
 769             return ret;
 770         }
 771     }
 772     return 0;
 773 }
 774
 775 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent);
 776
 777 static Property virtser_props[] = {
 778     DEFINE_PROP_UINT32("nr", VirtIOSerialPort, id, VIRTIO_CONSOLE_BAD_ID),
 779     DEFINE_PROP_STRING("name", VirtIOSerialPort, name),
 780     DEFINE_PROP_END_OF_LIST()
 781 };
 782
 783 #define TYPE_VIRTIO_SERIAL_BUS "virtio-serial-bus"
 784 #define VIRTIO_SERIAL_BUS(obj) \
 785       OBJECT_CHECK(VirtIOSerialBus, (obj), TYPE_VIRTIO_SERIAL_BUS)
 786
 787 static void virtser_bus_class_init(ObjectClass *klass, void *data)
 788 {
 789     BusClass *k = BUS_CLASS(klass);
 790     k->print_dev = virtser_bus_dev_print;
 791 }
 792
 793 static const TypeInfo virtser_bus_info = {
 794     .name = TYPE_VIRTIO_SERIAL_BUS,
 795     .parent = TYPE_BUS,
 796     .instance_size = sizeof(VirtIOSerialBus),
 797     .class_init = virtser_bus_class_init,
 798 };
 799
 800 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent)
 801 {
 802     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(qdev);
 803
 804     monitor_printf(mon, "%*sport %d, guest %s, host %s, throttle %s\n",
 805                    indent, "", port->id,
 806                    port->guest_connected ? "on" : "off",
 807                    port->host_connected ? "on" : "off",
 808                    port->throttled ? "on" : "off");
 809 }
 810
 811 /* This function is only used if a port id is not provided by the user */
 812 static uint32_t find_free_port_id(VirtIOSerial *vser)
 813 {
 814     unsigned int i, max_nr_ports;
 815
 816     max_nr_ports = vser->serial.max_virtserial_ports;
 817     for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
 818         uint32_t map, zeroes;
 819
 820         map = vser->ports_map[i];
 821         zeroes = ctz32(~map);
 822         if (zeroes != 32) {
 823             return zeroes + i * 32;
 824         }
 825     }
 826     return VIRTIO_CONSOLE_BAD_ID;
 827 }
 828
 829 static void mark_port_added(VirtIOSerial *vser, uint32_t port_id)
 830 {
 831     unsigned int i;
 832
 833     i = port_id / 32;
 834     vser->ports_map[i] |= 1U << (port_id % 32);
 835 }
 836
 837 static void add_port(VirtIOSerial *vser, uint32_t port_id)
 838 {
 839     mark_port_added(vser, port_id);
 840     send_control_event(vser, port_id, VIRTIO_CONSOLE_PORT_ADD, 1);
 841 }
 842
 843 static void remove_port(VirtIOSerial *vser, uint32_t port_id)
 844 {
 845     VirtIOSerialPort *port;
 846
 847     /*
 848      * Don't mark port 0 removed -- we explicitly reserve it for
 849      * backward compat with older guests, ensure a virtconsole device
 850      * unplug retains the reservation.
 851      */
 852     if (port_id) {
 853         unsigned int i;
 854
 855         i = port_id / 32;
 856         vser->ports_map[i] &= ~(1U << (port_id % 32));
 857     }
 858
 859     port = find_port_by_id(vser, port_id);
 860     /*
 861      * This function is only called from qdev's unplug callback; if we
 862      * get a NULL port here, we're in trouble.
 863      */
 864     assert(port);
 865
 866     /* Flush out any unconsumed buffers first */
 867     discard_vq_data(port->ovq, VIRTIO_DEVICE(port->vser));
 868
 869     send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_REMOVE, 1);
 870 }
 871
 872 static void virtser_port_device_realize(DeviceState *dev, Error **errp)
 873 {
 874     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
 875     VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 876     VirtIOSerialBus *bus = VIRTIO_SERIAL_BUS(qdev_get_parent_bus(dev));
 877     int max_nr_ports;
 878     bool plugging_port0;
 879     Error *err = NULL;
 880
 881     port->vser = bus->vser;
 882     port->bh = qemu_bh_new(flush_queued_data_bh, port);
 883
 884     assert(vsc->have_data);
 885
 886     /*
 887      * Is the first console port we're seeing? If so, put it up at
 888      * location 0. This is done for backward compatibility (old
 889      * kernel, new qemu).
 890      */
 891     plugging_port0 = vsc->is_console && !find_port_by_id(port->vser, 0);
 892
 893     if (find_port_by_id(port->vser, port->id)) {
 894         error_setg(errp, "virtio-serial-bus: A port already exists at id %u",
 895                    port->id);
 896         return;
 897     }
 898
 899     if (port->name != NULL && find_port_by_name(port->name)) {
 900         error_setg(errp, "virtio-serial-bus: A port already exists by name %s",
 901                    port->name);
 902         return;
 903     }
 904
 905     if (port->id == VIRTIO_CONSOLE_BAD_ID) {
 906         if (plugging_port0) {
 907             port->id = 0;
 908         } else {
 909             port->id = find_free_port_id(port->vser);
 910             if (port->id == VIRTIO_CONSOLE_BAD_ID) {
 911                 error_setg(errp, "virtio-serial-bus: Maximum port limit for "
 912                                  "this device reached");
 913                 return;
 914             }
 915         }
 916     }
 917
 918     max_nr_ports = port->vser->serial.max_virtserial_ports;
 919     if (port->id >= max_nr_ports) {
 920         error_setg(errp, "virtio-serial-bus: Out-of-range port id specified, "
 921                          "max. allowed: %u", max_nr_ports - 1);
 922         return;
 923     }
 924
 925     vsc->realize(dev, &err);
 926     if (err != NULL) {
 927         error_propagate(errp, err);
 928         return;
 929     }
 930
 931     port->elem.out_num = 0;
 932 }
 933
 934 static void virtser_port_device_plug(HotplugHandler *hotplug_dev,
 935                                      DeviceState *dev, Error **errp)
 936 {
 937     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
 938
 939     QTAILQ_INSERT_TAIL(&port->vser->ports, port, next);
 940     port->ivq = port->vser->ivqs[port->id];
 941     port->ovq = port->vser->ovqs[port->id];
 942
 943     add_port(port->vser, port->id);
 944
 945     /* Send an update to the guest about this new port added */
 946     virtio_notify_config(VIRTIO_DEVICE(hotplug_dev));
 947 }
 948
 949 static void virtser_port_device_unrealize(DeviceState *dev, Error **errp)
 950 {
 951     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
 952     VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(dev);
 953     VirtIOSerial *vser = port->vser;
 954
 955     qemu_bh_delete(port->bh);
 956     remove_port(port->vser, port->id);
 957
 958     QTAILQ_REMOVE(&vser->ports, port, next);
 959
 960     if (vsc->unrealize) {
 961         vsc->unrealize(dev, errp);
 962     }
 963 }
 964
 965 static void virtio_serial_device_realize(DeviceState *dev, Error **errp)
 966 {
 967     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
 968     VirtIOSerial *vser = VIRTIO_SERIAL(dev);
 969     uint32_t i, max_supported_ports;
 970
 971     if (!vser->serial.max_virtserial_ports) {
 972         error_setg(errp, "Maximum number of serial ports not specified");
 973         return;
 974     }
 975
 976     /* Each port takes 2 queues, and one pair is for the control queue */
 977     max_supported_ports = VIRTIO_QUEUE_MAX / 2 - 1;
 978
 979     if (vser->serial.max_virtserial_ports > max_supported_ports) {
 980         error_setg(errp, "maximum ports supported: %u", max_supported_ports);
 981         return;
 982     }
 983
 984     /* We don't support emergency write, skip it for now. */
 985     /* TODO: cleaner fix, depending on host features. */
 986     virtio_init(vdev, "virtio-serial", VIRTIO_ID_CONSOLE,
 987                 offsetof(struct virtio_console_config, emerg_wr));
 988
 989     /* Spawn a new virtio-serial bus on which the ports will ride as devices */
 990     qbus_create_inplace(&vser->bus, sizeof(vser->bus), TYPE_VIRTIO_SERIAL_BUS,
 991                         dev, vdev->bus_name);
 992     qbus_set_hotplug_handler(BUS(&vser->bus), DEVICE(vser), errp);
 993     vser->bus.vser = vser;
 994     QTAILQ_INIT(&vser->ports);
 995
 996     vser->bus.max_nr_ports = vser->serial.max_virtserial_ports;
 997     vser->ivqs = g_malloc(vser->serial.max_virtserial_ports
 998                           * sizeof(VirtQueue *));
 999     vser->ovqs = g_malloc(vser->serial.max_virtserial_ports
1000                           * sizeof(VirtQueue *));
1001
1002     /* Add a queue for host to guest transfers for port 0 (backward compat) */
1003     vser->ivqs[0] = virtio_add_queue(vdev, 128, handle_input);
1004     /* Add a queue for guest to host transfers for port 0 (backward compat) */
1005     vser->ovqs[0] = virtio_add_queue(vdev, 128, handle_output);
1006
1007     /* TODO: host to guest notifications can get dropped
1008      * if the queue fills up. Implement queueing in host,
1009      * this might also make it possible to reduce the control
1010      * queue size: as guest preposts buffers there,
1011      * this will save 4Kbyte of guest memory per entry. */
1012
1013     /* control queue: host to guest */
1014     vser->c_ivq = virtio_add_queue(vdev, 32, control_in);
1015     /* control queue: guest to host */
1016     vser->c_ovq = virtio_add_queue(vdev, 32, control_out);
1017
1018     for (i = 1; i < vser->bus.max_nr_ports; i++) {
1019         /* Add a per-port queue for host to guest transfers */
1020         vser->ivqs[i] = virtio_add_queue(vdev, 128, handle_input);
1021         /* Add a per-per queue for guest to host transfers */
1022         vser->ovqs[i] = virtio_add_queue(vdev, 128, handle_output);
1023     }
1024
1025     vser->ports_map = g_malloc0(((vser->serial.max_virtserial_ports + 31) / 32)
1026         * sizeof(vser->ports_map[0]));
1027     /*
1028      * Reserve location 0 for a console port for backward compat
1029      * (old kernel, new qemu)
1030      */
1031     mark_port_added(vser, 0);
1032
1033     vser->post_load = NULL;
1034
1035     /*
1036      * Register for the savevm section with the virtio-console name
1037      * to preserve backward compat
1038      */
1039     register_savevm(dev, "virtio-console", -1, 3, virtio_serial_save,
1040                     virtio_serial_load, vser);
1041
1042     QLIST_INSERT_HEAD(&vserdevices.devices, vser, next);
1043 }
1044
1045 static void virtio_serial_port_class_init(ObjectClass *klass, void *data)
1046 {
1047     DeviceClass *k = DEVICE_CLASS(klass);
1048
1049     set_bit(DEVICE_CATEGORY_INPUT, k->categories);
1050     k->bus_type = TYPE_VIRTIO_SERIAL_BUS;
1051     k->realize = virtser_port_device_realize;
1052     k->unrealize = virtser_port_device_unrealize;
1053     k->props = virtser_props;
1054 }
1055
1056 static const TypeInfo virtio_serial_port_type_info = {
1057     .name = TYPE_VIRTIO_SERIAL_PORT,
1058     .parent = TYPE_DEVICE,
1059     .instance_size = sizeof(VirtIOSerialPort),
1060     .abstract = true,
1061     .class_size = sizeof(VirtIOSerialPortClass),
1062     .class_init = virtio_serial_port_class_init,
1063 };
1064
1065 static void virtio_serial_device_unrealize(DeviceState *dev, Error **errp)
1066 {
1067     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
1068     VirtIOSerial *vser = VIRTIO_SERIAL(dev);
1069
1070     QLIST_REMOVE(vser, next);
1071
1072     unregister_savevm(dev, "virtio-console", vser);
1073
1074     g_free(vser->ivqs);
1075     g_free(vser->ovqs);
1076     g_free(vser->ports_map);
1077     if (vser->post_load) {
1078         g_free(vser->post_load->connected);
1079         timer_del(vser->post_load->timer);
1080         timer_free(vser->post_load->timer);
1081         g_free(vser->post_load);
1082     }
1083     virtio_cleanup(vdev);
1084 }
1085
1086 static Property virtio_serial_properties[] = {
1087     DEFINE_PROP_UINT32("max_ports", VirtIOSerial, serial.max_virtserial_ports,
1088                                                   31),
1089     DEFINE_PROP_END_OF_LIST(),
1090 };
1091
1092 static void virtio_serial_class_init(ObjectClass *klass, void *data)
1093 {
1094     DeviceClass *dc = DEVICE_CLASS(klass);
1095     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
1096     HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
1097
1098     QLIST_INIT(&vserdevices.devices);
1099
1100     dc->props = virtio_serial_properties;
1101     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
1102     vdc->realize = virtio_serial_device_realize;
1103     vdc->unrealize = virtio_serial_device_unrealize;
1104     vdc->get_features = get_features;
1105     vdc->get_config = get_config;
1106     vdc->set_status = set_status;
1107     vdc->reset = vser_reset;
1108     vdc->save = virtio_serial_save_device;
1109     vdc->load = virtio_serial_load_device;
1110     hc->plug = virtser_port_device_plug;
1111     hc->unplug = qdev_simple_device_unplug_cb;
1112 }
1113
1114 static const TypeInfo virtio_device_info = {
1115     .name = TYPE_VIRTIO_SERIAL,
1116     .parent = TYPE_VIRTIO_DEVICE,
1117     .instance_size = sizeof(VirtIOSerial),
1118     .class_init = virtio_serial_class_init,
1119     .interfaces = (InterfaceInfo[]) {
1120         { TYPE_HOTPLUG_HANDLER },
1121         { }
1122     }
1123 };
1124
1125 static void virtio_serial_register_types(void)
1126 {
1127     type_register_static(&virtser_bus_info);
1128     type_register_static(&virtio_serial_port_type_info);
1129     type_register_static(&virtio_device_info);
1130 }
1131
1132 type_init(virtio_serial_register_types)