hw/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
  18 #include "iov.h"
  19 #include "monitor.h"
  20 #include "qemu-queue.h"
  21 #include "sysbus.h"
  22 #include "virtio-serial.h"
  23
  24 /* The virtio-serial bus on top of which the ports will ride as devices */
  25 struct VirtIOSerialBus {
  26     BusState qbus;
  27
  28     /* This is the parent device that provides the bus for ports. */
  29     VirtIOSerial *vser;
  30
  31     /* The maximum number of ports that can ride on top of this bus */
  32     uint32_t max_nr_ports;
  33 };
  34
  35 struct VirtIOSerial {
  36     VirtIODevice vdev;
  37
  38     VirtQueue *c_ivq, *c_ovq;
  39     /* Arrays of ivqs and ovqs: one per port */
  40     VirtQueue **ivqs, **ovqs;
  41
  42     VirtIOSerialBus *bus;
  43
  44     DeviceState *qdev;
  45
  46     QTAILQ_HEAD(, VirtIOSerialPort) ports;
  47
  48     /* bitmap for identifying active ports */
  49     uint32_t *ports_map;
  50
  51     struct virtio_console_config config;
  52 };
  53
  54 static VirtIOSerialPort *find_port_by_id(VirtIOSerial *vser, uint32_t id)
  55 {
  56     VirtIOSerialPort *port;
  57
  58     if (id == VIRTIO_CONSOLE_BAD_ID) {
  59         return NULL;
  60     }
  61
  62     QTAILQ_FOREACH(port, &vser->ports, next) {
  63         if (port->id == id)
  64             return port;
  65     }
  66     return NULL;
  67 }
  68
  69 static VirtIOSerialPort *find_port_by_vq(VirtIOSerial *vser, VirtQueue *vq)
  70 {
  71     VirtIOSerialPort *port;
  72
  73     QTAILQ_FOREACH(port, &vser->ports, next) {
  74         if (port->ivq == vq || port->ovq == vq)
  75             return port;
  76     }
  77     return NULL;
  78 }
  79
  80 static bool use_multiport(VirtIOSerial *vser)
  81 {
  82     return vser->vdev.guest_features & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
  83 }
  84
  85 static size_t write_to_port(VirtIOSerialPort *port,
  86                             const uint8_t *buf, size_t size)
  87 {
  88     VirtQueueElement elem;
  89     VirtQueue *vq;
  90     size_t offset;
  91
  92     vq = port->ivq;
  93     if (!virtio_queue_ready(vq)) {
  94         return 0;
  95     }
  96
  97     offset = 0;
  98     while (offset < size) {
  99         size_t len;
 100
 101         if (!virtqueue_pop(vq, &elem)) {
 102             break;
 103         }
 104
 105         len = iov_from_buf(elem.in_sg, elem.in_num,
 106                            buf + offset, size - offset);
 107         offset += len;
 108
 109         virtqueue_push(vq, &elem, len);
 110     }
 111
 112     virtio_notify(&port->vser->vdev, vq);
 113     return offset;
 114 }
 115
 116 static void discard_vq_data(VirtQueue *vq, VirtIODevice *vdev)
 117 {
 118     VirtQueueElement elem;
 119
 120     if (!virtio_queue_ready(vq)) {
 121         return;
 122     }
 123     while (virtqueue_pop(vq, &elem)) {
 124         virtqueue_push(vq, &elem, 0);
 125     }
 126     virtio_notify(vdev, vq);
 127 }
 128
 129 static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq,
 130                                  VirtIODevice *vdev)
 131 {
 132     assert(port);
 133     assert(virtio_queue_ready(vq));
 134
 135     while (!port->throttled) {
 136         unsigned int i;
 137
 138         /* Pop an elem only if we haven't left off a previous one mid-way */
 139         if (!port->elem.out_num) {
 140             if (!virtqueue_pop(vq, &port->elem)) {
 141                 break;
 142             }
 143             port->iov_idx = 0;
 144             port->iov_offset = 0;
 145         }
 146
 147         for (i = port->iov_idx; i < port->elem.out_num; i++) {
 148             size_t buf_size;
 149             ssize_t ret;
 150
 151             buf_size = port->elem.out_sg[i].iov_len - port->iov_offset;
 152             ret = port->info->have_data(port,
 153                                         port->elem.out_sg[i].iov_base
 154                                           + port->iov_offset,
 155                                         buf_size);
 156             if (ret < 0 && ret != -EAGAIN) {
 157                 /* We don't handle any other type of errors here */
 158                 abort();
 159             }
 160             if (ret == -EAGAIN || (ret >= 0 && ret < buf_size)) {
 161                 virtio_serial_throttle_port(port, true);
 162                 port->iov_idx = i;
 163                 if (ret > 0) {
 164                     port->iov_offset += ret;
 165                 }
 166                 break;
 167             }
 168             port->iov_offset = 0;
 169         }
 170         if (port->throttled) {
 171             break;
 172         }
 173         virtqueue_push(vq, &port->elem, 0);
 174         port->elem.out_num = 0;
 175     }
 176     virtio_notify(vdev, vq);
 177 }
 178
 179 static void flush_queued_data(VirtIOSerialPort *port)
 180 {
 181     assert(port);
 182
 183     if (!virtio_queue_ready(port->ovq)) {
 184         return;
 185     }
 186     do_flush_queued_data(port, port->ovq, &port->vser->vdev);
 187 }
 188
 189 static size_t send_control_msg(VirtIOSerialPort *port, void *buf, size_t len)
 190 {
 191     VirtQueueElement elem;
 192     VirtQueue *vq;
 193     struct virtio_console_control *cpkt;
 194
 195     vq = port->vser->c_ivq;
 196     if (!virtio_queue_ready(vq)) {
 197         return 0;
 198     }
 199     if (!virtqueue_pop(vq, &elem)) {
 200         return 0;
 201     }
 202
 203     cpkt = (struct virtio_console_control *)buf;
 204     stl_p(&cpkt->id, port->id);
 205     memcpy(elem.in_sg[0].iov_base, buf, len);
 206
 207     virtqueue_push(vq, &elem, len);
 208     virtio_notify(&port->vser->vdev, vq);
 209     return len;
 210 }
 211
 212 static size_t send_control_event(VirtIOSerialPort *port, uint16_t event,
 213                                  uint16_t value)
 214 {
 215     struct virtio_console_control cpkt;
 216
 217     stw_p(&cpkt.event, event);
 218     stw_p(&cpkt.value, value);
 219
 220     return send_control_msg(port, &cpkt, sizeof(cpkt));
 221 }
 222
 223 /* Functions for use inside qemu to open and read from/write to ports */
 224 int virtio_serial_open(VirtIOSerialPort *port)
 225 {
 226     /* Don't allow opening an already-open port */
 227     if (port->host_connected) {
 228         return 0;
 229     }
 230     /* Send port open notification to the guest */
 231     port->host_connected = true;
 232     send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
 233
 234     return 0;
 235 }
 236
 237 int virtio_serial_close(VirtIOSerialPort *port)
 238 {
 239     port->host_connected = false;
 240     /*
 241      * If there's any data the guest sent which the app didn't
 242      * consume, reset the throttling flag and discard the data.
 243      */
 244     port->throttled = false;
 245     discard_vq_data(port->ovq, &port->vser->vdev);
 246
 247     send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
 248
 249     return 0;
 250 }
 251
 252 /* Individual ports/apps call this function to write to the guest. */
 253 ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
 254                             size_t size)
 255 {
 256     if (!port || !port->host_connected || !port->guest_connected) {
 257         return 0;
 258     }
 259     return write_to_port(port, buf, size);
 260 }
 261
 262 /*
 263  * Readiness of the guest to accept data on a port.
 264  * Returns max. data the guest can receive
 265  */
 266 size_t virtio_serial_guest_ready(VirtIOSerialPort *port)
 267 {
 268     VirtQueue *vq = port->ivq;
 269
 270     if (!virtio_queue_ready(vq) ||
 271         !(port->vser->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
 279     if (virtqueue_avail_bytes(vq, 4096, 0)) {
 280         return 4096;
 281     }
 282     if (virtqueue_avail_bytes(vq, 1, 0)) {
 283         return 1;
 284     }
 285     return 0;
 286 }
 287
 288 void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle)
 289 {
 290     if (!port) {
 291         return;
 292     }
 293
 294     port->throttled = throttle;
 295     if (throttle) {
 296         return;
 297     }
 298
 299     flush_queued_data(port);
 300 }
 301
 302 /* Guest wants to notify us of some event */
 303 static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len)
 304 {
 305     struct VirtIOSerialPort *port;
 306     struct virtio_console_control cpkt, *gcpkt;
 307     uint8_t *buffer;
 308     size_t buffer_len;
 309
 310     gcpkt = buf;
 311
 312     if (len < sizeof(cpkt)) {
 313         /* The guest sent an invalid control packet */
 314         return;
 315     }
 316
 317     cpkt.event = lduw_p(&gcpkt->event);
 318     cpkt.value = lduw_p(&gcpkt->value);
 319
 320     port = find_port_by_id(vser, ldl_p(&gcpkt->id));
 321     if (!port && cpkt.event != VIRTIO_CONSOLE_DEVICE_READY)
 322         return;
 323
 324     switch(cpkt.event) {
 325     case VIRTIO_CONSOLE_DEVICE_READY:
 326         if (!cpkt.value) {
 327             error_report("virtio-serial-bus: Guest failure in adding device %s\n",
 328                          vser->bus->qbus.name);
 329             break;
 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(port, VIRTIO_CONSOLE_PORT_ADD, 1);
 337         }
 338         break;
 339
 340     case VIRTIO_CONSOLE_PORT_READY:
 341         if (!cpkt.value) {
 342             error_report("virtio-serial-bus: Guest failure in adding port %u for device %s\n",
 343                          port->id, vser->bus->qbus.name);
 344             break;
 345         }
 346         /*
 347          * Now that we know the guest asked for the port name, we're
 348          * sure the guest has initialised whatever state is necessary
 349          * for this port. Now's a good time to let the guest know if
 350          * this port is a console port so that the guest can hook it
 351          * up to hvc.
 352          */
 353         if (port->is_console) {
 354             send_control_event(port, VIRTIO_CONSOLE_CONSOLE_PORT, 1);
 355         }
 356
 357         if (port->name) {
 358             stw_p(&cpkt.event, VIRTIO_CONSOLE_PORT_NAME);
 359             stw_p(&cpkt.value, 1);
 360
 361             buffer_len = sizeof(cpkt) + strlen(port->name) + 1;
 362             buffer = qemu_malloc(buffer_len);
 363
 364             memcpy(buffer, &cpkt, sizeof(cpkt));
 365             memcpy(buffer + sizeof(cpkt), port->name, strlen(port->name));
 366             buffer[buffer_len - 1] = 0;
 367
 368             send_control_msg(port, buffer, buffer_len);
 369             qemu_free(buffer);
 370         }
 371
 372         if (port->host_connected) {
 373             send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
 374         }
 375
 376         /*
 377          * When the guest has asked us for this information it means
 378          * the guest is all setup and has its virtqueues
 379          * initialised. If some app is interested in knowing about
 380          * this event, let it know.
 381          */
 382         if (port->info->guest_ready) {
 383             port->info->guest_ready(port);
 384         }
 385         break;
 386
 387     case VIRTIO_CONSOLE_PORT_OPEN:
 388         port->guest_connected = cpkt.value;
 389         if (cpkt.value && port->info->guest_open) {
 390             /* Send the guest opened notification if an app is interested */
 391             port->info->guest_open(port);
 392         }
 393
 394         if (!cpkt.value && port->info->guest_close) {
 395             /* Send the guest closed notification if an app is interested */
 396             port->info->guest_close(port);
 397         }
 398         break;
 399     }
 400 }
 401
 402 static void control_in(VirtIODevice *vdev, VirtQueue *vq)
 403 {
 404 }
 405
 406 static void control_out(VirtIODevice *vdev, VirtQueue *vq)
 407 {
 408     VirtQueueElement elem;
 409     VirtIOSerial *vser;
 410     uint8_t *buf;
 411     size_t len;
 412
 413     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 414
 415     len = 0;
 416     buf = NULL;
 417     while (virtqueue_pop(vq, &elem)) {
 418         size_t cur_len, copied;
 419
 420         cur_len = iov_size(elem.out_sg, elem.out_num);
 421         /*
 422          * Allocate a new buf only if we didn't have one previously or
 423          * if the size of the buf differs
 424          */
 425         if (cur_len > len) {
 426             qemu_free(buf);
 427
 428             buf = qemu_malloc(cur_len);
 429             len = cur_len;
 430         }
 431         copied = iov_to_buf(elem.out_sg, elem.out_num, buf, 0, len);
 432
 433         handle_control_message(vser, buf, copied);
 434         virtqueue_push(vq, &elem, 0);
 435     }
 436     qemu_free(buf);
 437     virtio_notify(vdev, vq);
 438 }
 439
 440 /* Guest wrote something to some port. */
 441 static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
 442 {
 443     VirtIOSerial *vser;
 444     VirtIOSerialPort *port;
 445
 446     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 447     port = find_port_by_vq(vser, vq);
 448
 449     if (!port || !port->host_connected || !port->info->have_data) {
 450         discard_vq_data(vq, vdev);
 451         return;
 452     }
 453
 454     if (!port->throttled) {
 455         do_flush_queued_data(port, vq, vdev);
 456         return;
 457     }
 458 }
 459
 460 static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
 461 {
 462 }
 463
 464 static uint32_t get_features(VirtIODevice *vdev, uint32_t features)
 465 {
 466     VirtIOSerial *vser;
 467
 468     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 469
 470     if (vser->bus->max_nr_ports > 1) {
 471         features |= (1 << VIRTIO_CONSOLE_F_MULTIPORT);
 472     }
 473     return features;
 474 }
 475
 476 /* Guest requested config info */
 477 static void get_config(VirtIODevice *vdev, uint8_t *config_data)
 478 {
 479     VirtIOSerial *vser;
 480
 481     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 482     memcpy(config_data, &vser->config, sizeof(struct virtio_console_config));
 483 }
 484
 485 static void set_config(VirtIODevice *vdev, const uint8_t *config_data)
 486 {
 487     struct virtio_console_config config;
 488
 489     memcpy(&config, config_data, sizeof(config));
 490 }
 491
 492 static void virtio_serial_save(QEMUFile *f, void *opaque)
 493 {
 494     VirtIOSerial *s = opaque;
 495     VirtIOSerialPort *port;
 496     uint32_t nr_active_ports;
 497     unsigned int i, max_nr_ports;
 498
 499     /* The virtio device */
 500     virtio_save(&s->vdev, f);
 501
 502     /* The config space */
 503     qemu_put_be16s(f, &s->config.cols);
 504     qemu_put_be16s(f, &s->config.rows);
 505
 506     qemu_put_be32s(f, &s->config.max_nr_ports);
 507
 508     /* The ports map */
 509     max_nr_ports = tswap32(s->config.max_nr_ports);
 510     for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
 511         qemu_put_be32s(f, &s->ports_map[i]);
 512     }
 513
 514     /* Ports */
 515
 516     nr_active_ports = 0;
 517     QTAILQ_FOREACH(port, &s->ports, next) {
 518         nr_active_ports++;
 519     }
 520
 521     qemu_put_be32s(f, &nr_active_ports);
 522
 523     /*
 524      * Items in struct VirtIOSerialPort.
 525      */
 526     QTAILQ_FOREACH(port, &s->ports, next) {
 527         uint32_t elem_popped;
 528
 529         qemu_put_be32s(f, &port->id);
 530         qemu_put_byte(f, port->guest_connected);
 531         qemu_put_byte(f, port->host_connected);
 532
 533         elem_popped = 0;
 534         if (port->elem.out_num) {
 535             elem_popped = 1;
 536         }
 537         qemu_put_be32s(f, &elem_popped);
 538         if (elem_popped) {
 539             qemu_put_be32s(f, &port->iov_idx);
 540             qemu_put_be64s(f, &port->iov_offset);
 541
 542             qemu_put_buffer(f, (unsigned char *)&port->elem,
 543                             sizeof(port->elem));
 544         }
 545     }
 546 }
 547
 548 static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
 549 {
 550     VirtIOSerial *s = opaque;
 551     VirtIOSerialPort *port;
 552     uint32_t max_nr_ports, nr_active_ports, ports_map;
 553     unsigned int i;
 554
 555     if (version_id > 3) {
 556         return -EINVAL;
 557     }
 558
 559     /* The virtio device */
 560     virtio_load(&s->vdev, f);
 561
 562     if (version_id < 2) {
 563         return 0;
 564     }
 565
 566     /* The config space */
 567     qemu_get_be16s(f, &s->config.cols);
 568     qemu_get_be16s(f, &s->config.rows);
 569
 570     qemu_get_be32s(f, &max_nr_ports);
 571     tswap32s(&max_nr_ports);
 572     if (max_nr_ports > tswap32(s->config.max_nr_ports)) {
 573         /* Source could have had more ports than us. Fail migration. */
 574         return -EINVAL;
 575     }
 576
 577     for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
 578         qemu_get_be32s(f, &ports_map);
 579
 580         if (ports_map != s->ports_map[i]) {
 581             /*
 582              * Ports active on source and destination don't
 583              * match. Fail migration.
 584              */
 585             return -EINVAL;
 586         }
 587     }
 588
 589     qemu_get_be32s(f, &nr_active_ports);
 590
 591     /* Items in struct VirtIOSerialPort */
 592     for (i = 0; i < nr_active_ports; i++) {
 593         uint32_t id;
 594         bool host_connected;
 595
 596         id = qemu_get_be32(f);
 597         port = find_port_by_id(s, id);
 598         if (!port) {
 599             return -EINVAL;
 600         }
 601
 602         port->guest_connected = qemu_get_byte(f);
 603         host_connected = qemu_get_byte(f);
 604         if (host_connected != port->host_connected) {
 605             /*
 606              * We have to let the guest know of the host connection
 607              * status change
 608              */
 609             send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN,
 610                                port->host_connected);
 611         }
 612
 613         if (version_id > 2) {
 614             uint32_t elem_popped;
 615
 616             qemu_get_be32s(f, &elem_popped);
 617             if (elem_popped) {
 618                 qemu_get_be32s(f, &port->iov_idx);
 619                 qemu_get_be64s(f, &port->iov_offset);
 620
 621                 qemu_get_buffer(f, (unsigned char *)&port->elem,
 622                                 sizeof(port->elem));
 623                 virtqueue_map_sg(port->elem.in_sg, port->elem.in_addr,
 624                                  port->elem.in_num, 1);
 625                 virtqueue_map_sg(port->elem.out_sg, port->elem.out_addr,
 626                                  port->elem.out_num, 1);
 627
 628                 /*
 629                  *  Port was throttled on source machine.  Let's
 630                  *  unthrottle it here so data starts flowing again.
 631                  */
 632                 virtio_serial_throttle_port(port, false);
 633             }
 634         }
 635     }
 636     return 0;
 637 }
 638
 639 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent);
 640
 641 static struct BusInfo virtser_bus_info = {
 642     .name      = "virtio-serial-bus",
 643     .size      = sizeof(VirtIOSerialBus),
 644     .print_dev = virtser_bus_dev_print,
 645 };
 646
 647 static VirtIOSerialBus *virtser_bus_new(DeviceState *dev)
 648 {
 649     VirtIOSerialBus *bus;
 650
 651     bus = FROM_QBUS(VirtIOSerialBus, qbus_create(&virtser_bus_info, dev, NULL));
 652     bus->qbus.allow_hotplug = 1;
 653
 654     return bus;
 655 }
 656
 657 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent)
 658 {
 659     VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, qdev);
 660
 661     monitor_printf(mon, "%*s dev-prop-int: id: %u\n",
 662                    indent, "", port->id);
 663     monitor_printf(mon, "%*s dev-prop-int: guest_connected: %d\n",
 664                    indent, "", port->guest_connected);
 665     monitor_printf(mon, "%*s dev-prop-int: host_connected: %d\n",
 666                    indent, "", port->host_connected);
 667     monitor_printf(mon, "%*s dev-prop-int: throttled: %d\n",
 668                    indent, "", port->throttled);
 669 }
 670
 671 /* This function is only used if a port id is not provided by the user */
 672 static uint32_t find_free_port_id(VirtIOSerial *vser)
 673 {
 674     unsigned int i, max_nr_ports;
 675
 676     max_nr_ports = tswap32(vser->config.max_nr_ports);
 677     for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
 678         uint32_t map, bit;
 679
 680         map = vser->ports_map[i];
 681         bit = ffs(~map);
 682         if (bit) {
 683             return (bit - 1) + i * 32;
 684         }
 685     }
 686     return VIRTIO_CONSOLE_BAD_ID;
 687 }
 688
 689 static void mark_port_added(VirtIOSerial *vser, uint32_t port_id)
 690 {
 691     unsigned int i;
 692
 693     i = port_id / 32;
 694     vser->ports_map[i] |= 1U << (port_id % 32);
 695 }
 696
 697 static void add_port(VirtIOSerial *vser, uint32_t port_id)
 698 {
 699     mark_port_added(vser, port_id);
 700
 701     send_control_event(find_port_by_id(vser, port_id),
 702                        VIRTIO_CONSOLE_PORT_ADD, 1);
 703 }
 704
 705 static void remove_port(VirtIOSerial *vser, uint32_t port_id)
 706 {
 707     VirtIOSerialPort *port;
 708     unsigned int i;
 709
 710     i = port_id / 32;
 711     vser->ports_map[i] &= ~(1U << (port_id % 32));
 712
 713     port = find_port_by_id(vser, port_id);
 714     /* Flush out any unconsumed buffers first */
 715     discard_vq_data(port->ovq, &port->vser->vdev);
 716
 717     send_control_event(port, VIRTIO_CONSOLE_PORT_REMOVE, 1);
 718 }
 719
 720 static int virtser_port_qdev_init(DeviceState *qdev, DeviceInfo *base)
 721 {
 722     VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, qdev);
 723     VirtIOSerialPortInfo *info = DO_UPCAST(VirtIOSerialPortInfo, qdev, base);
 724     VirtIOSerialBus *bus = DO_UPCAST(VirtIOSerialBus, qbus, qdev->parent_bus);
 725     int ret, max_nr_ports;
 726     bool plugging_port0;
 727
 728     port->vser = bus->vser;
 729
 730     /*
 731      * Is the first console port we're seeing? If so, put it up at
 732      * location 0. This is done for backward compatibility (old
 733      * kernel, new qemu).
 734      */
 735     plugging_port0 = port->is_console && !find_port_by_id(port->vser, 0);
 736
 737     if (find_port_by_id(port->vser, port->id)) {
 738         error_report("virtio-serial-bus: A port already exists at id %u\n",
 739                      port->id);
 740         return -1;
 741     }
 742
 743     if (port->id == VIRTIO_CONSOLE_BAD_ID) {
 744         if (plugging_port0) {
 745             port->id = 0;
 746         } else {
 747             port->id = find_free_port_id(port->vser);
 748             if (port->id == VIRTIO_CONSOLE_BAD_ID) {
 749                 error_report("virtio-serial-bus: Maximum port limit for this device reached\n");
 750                 return -1;
 751             }
 752         }
 753     }
 754
 755     max_nr_ports = tswap32(port->vser->config.max_nr_ports);
 756     if (port->id >= max_nr_ports) {
 757         error_report("virtio-serial-bus: Out-of-range port id specified, max. allowed: %u\n",
 758                      max_nr_ports - 1);
 759         return -1;
 760     }
 761
 762     port->info = info;
 763     ret = info->init(port);
 764     if (ret) {
 765         return ret;
 766     }
 767
 768     if (!use_multiport(port->vser)) {
 769         /*
 770          * Allow writes to guest in this case; we have no way of
 771          * knowing if a guest port is connected.
 772          */
 773         port->guest_connected = true;
 774     }
 775
 776     port->elem.out_num = 0;
 777
 778     QTAILQ_INSERT_TAIL(&port->vser->ports, port, next);
 779     port->ivq = port->vser->ivqs[port->id];
 780     port->ovq = port->vser->ovqs[port->id];
 781
 782     add_port(port->vser, port->id);
 783
 784     /* Send an update to the guest about this new port added */
 785     virtio_notify_config(&port->vser->vdev);
 786
 787     return ret;
 788 }
 789
 790 static int virtser_port_qdev_exit(DeviceState *qdev)
 791 {
 792     VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, qdev);
 793     VirtIOSerial *vser = port->vser;
 794
 795     remove_port(port->vser, port->id);
 796
 797     QTAILQ_REMOVE(&vser->ports, port, next);
 798
 799     if (port->info->exit)
 800         port->info->exit(port);
 801
 802     return 0;
 803 }
 804
 805 void virtio_serial_port_qdev_register(VirtIOSerialPortInfo *info)
 806 {
 807     info->qdev.init = virtser_port_qdev_init;
 808     info->qdev.bus_info = &virtser_bus_info;
 809     info->qdev.exit = virtser_port_qdev_exit;
 810     info->qdev.unplug = qdev_simple_unplug_cb;
 811     qdev_register(&info->qdev);
 812 }
 813
 814 VirtIODevice *virtio_serial_init(DeviceState *dev, virtio_serial_conf *conf)
 815 {
 816     VirtIOSerial *vser;
 817     VirtIODevice *vdev;
 818     uint32_t i, max_supported_ports;
 819
 820     if (!conf->max_virtserial_ports)
 821         return NULL;
 822
 823     /* Each port takes 2 queues, and one pair is for the control queue */
 824     max_supported_ports = VIRTIO_PCI_QUEUE_MAX / 2 - 1;
 825
 826     if (conf->max_virtserial_ports > max_supported_ports) {
 827         error_report("maximum ports supported: %u", max_supported_ports);
 828         return NULL;
 829     }
 830
 831     vdev = virtio_common_init("virtio-serial", VIRTIO_ID_CONSOLE,
 832                               sizeof(struct virtio_console_config),
 833                               sizeof(VirtIOSerial));
 834
 835     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 836
 837     /* Spawn a new virtio-serial bus on which the ports will ride as devices */
 838     vser->bus = virtser_bus_new(dev);
 839     vser->bus->vser = vser;
 840     QTAILQ_INIT(&vser->ports);
 841
 842     vser->bus->max_nr_ports = conf->max_virtserial_ports;
 843     vser->ivqs = qemu_malloc(conf->max_virtserial_ports * sizeof(VirtQueue *));
 844     vser->ovqs = qemu_malloc(conf->max_virtserial_ports * sizeof(VirtQueue *));
 845
 846     /* Add a queue for host to guest transfers for port 0 (backward compat) */
 847     vser->ivqs[0] = virtio_add_queue(vdev, 128, handle_input);
 848     /* Add a queue for guest to host transfers for port 0 (backward compat) */
 849     vser->ovqs[0] = virtio_add_queue(vdev, 128, handle_output);
 850
 851     /* TODO: host to guest notifications can get dropped
 852      * if the queue fills up. Implement queueing in host,
 853      * this might also make it possible to reduce the control
 854      * queue size: as guest preposts buffers there,
 855      * this will save 4Kbyte of guest memory per entry. */
 856
 857     /* control queue: host to guest */
 858     vser->c_ivq = virtio_add_queue(vdev, 32, control_in);
 859     /* control queue: guest to host */
 860     vser->c_ovq = virtio_add_queue(vdev, 32, control_out);
 861
 862     for (i = 1; i < vser->bus->max_nr_ports; i++) {
 863         /* Add a per-port queue for host to guest transfers */
 864         vser->ivqs[i] = virtio_add_queue(vdev, 128, handle_input);
 865         /* Add a per-per queue for guest to host transfers */
 866         vser->ovqs[i] = virtio_add_queue(vdev, 128, handle_output);
 867     }
 868
 869     vser->config.max_nr_ports = tswap32(conf->max_virtserial_ports);
 870     vser->ports_map = qemu_mallocz(((conf->max_virtserial_ports + 31) / 32)
 871         * sizeof(vser->ports_map[0]));
 872     /*
 873      * Reserve location 0 for a console port for backward compat
 874      * (old kernel, new qemu)
 875      */
 876     mark_port_added(vser, 0);
 877
 878     vser->vdev.get_features = get_features;
 879     vser->vdev.get_config = get_config;
 880     vser->vdev.set_config = set_config;
 881
 882     vser->qdev = dev;
 883
 884     /*
 885      * Register for the savevm section with the virtio-console name
 886      * to preserve backward compat
 887      */
 888     register_savevm(dev, "virtio-console", -1, 3, virtio_serial_save,
 889                     virtio_serial_load, vser);
 890
 891     return vdev;
 892 }
 893
 894 void virtio_serial_exit(VirtIODevice *vdev)
 895 {
 896     VirtIOSerial *vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 897
 898     unregister_savevm(vser->qdev, "virtio-console", vser);
 899
 900     qemu_free(vser->ivqs);
 901     qemu_free(vser->ovqs);
 902     qemu_free(vser->ports_map);
 903
 904     virtio_cleanup(vdev);
 905 }