hw/virtio-serial-bus.c

   1 /*
   2  * A bus for connecting virtio serial and console ports
   3  *
   4  * Copyright (C) 2009 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 "monitor.h"
  19 #include "qemu-queue.h"
  20 #include "sysbus.h"
  21 #include "virtio-serial.h"
  22
  23 /* The virtio-serial bus on top of which the ports will ride as devices */
  24 struct VirtIOSerialBus {
  25     BusState qbus;
  26
  27     /* This is the parent device that provides the bus for ports. */
  28     VirtIOSerial *vser;
  29
  30     /* The maximum number of ports that can ride on top of this bus */
  31     uint32_t max_nr_ports;
  32 };
  33
  34 struct VirtIOSerial {
  35     VirtIODevice vdev;
  36
  37     VirtQueue *c_ivq, *c_ovq;
  38     /* Arrays of ivqs and ovqs: one per port */
  39     VirtQueue **ivqs, **ovqs;
  40
  41     VirtIOSerialBus *bus;
  42
  43     QTAILQ_HEAD(, VirtIOSerialPort) ports;
  44     struct virtio_console_config config;
  45 };
  46
  47 static VirtIOSerialPort *find_port_by_id(VirtIOSerial *vser, uint32_t id)
  48 {
  49     VirtIOSerialPort *port;
  50
  51     QTAILQ_FOREACH(port, &vser->ports, next) {
  52         if (port->id == id)
  53             return port;
  54     }
  55     return NULL;
  56 }
  57
  58 static VirtIOSerialPort *find_port_by_vq(VirtIOSerial *vser, VirtQueue *vq)
  59 {
  60     VirtIOSerialPort *port;
  61
  62     QTAILQ_FOREACH(port, &vser->ports, next) {
  63         if (port->ivq == vq || port->ovq == vq)
  64             return port;
  65     }
  66     return NULL;
  67 }
  68
  69 static bool use_multiport(VirtIOSerial *vser)
  70 {
  71     return vser->vdev.guest_features & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
  72 }
  73
  74 static size_t write_to_port(VirtIOSerialPort *port,
  75                             const uint8_t *buf, size_t size)
  76 {
  77     VirtQueueElement elem;
  78     VirtQueue *vq;
  79     size_t offset = 0;
  80     size_t len = 0;
  81
  82     vq = port->ivq;
  83     if (!virtio_queue_ready(vq)) {
  84         return 0;
  85     }
  86     if (!size) {
  87         return 0;
  88     }
  89
  90     while (offset < size) {
  91         int i;
  92
  93         if (!virtqueue_pop(vq, &elem)) {
  94             break;
  95         }
  96
  97         for (i = 0; offset < size && i < elem.in_num; i++) {
  98             len = MIN(elem.in_sg[i].iov_len, size - offset);
  99
 100             memcpy(elem.in_sg[i].iov_base, buf + offset, len);
 101             offset += len;
 102         }
 103         virtqueue_push(vq, &elem, len);
 104     }
 105
 106     virtio_notify(&port->vser->vdev, vq);
 107     return offset;
 108 }
 109
 110 static size_t send_control_msg(VirtIOSerialPort *port, void *buf, size_t len)
 111 {
 112     VirtQueueElement elem;
 113     VirtQueue *vq;
 114     struct virtio_console_control *cpkt;
 115
 116     vq = port->vser->c_ivq;
 117     if (!virtio_queue_ready(vq)) {
 118         return 0;
 119     }
 120     if (!virtqueue_pop(vq, &elem)) {
 121         return 0;
 122     }
 123
 124     cpkt = (struct virtio_console_control *)buf;
 125     stl_p(&cpkt->id, port->id);
 126     memcpy(elem.in_sg[0].iov_base, buf, len);
 127
 128     virtqueue_push(vq, &elem, len);
 129     virtio_notify(&port->vser->vdev, vq);
 130     return len;
 131 }
 132
 133 static size_t send_control_event(VirtIOSerialPort *port, uint16_t event,
 134                                  uint16_t value)
 135 {
 136     struct virtio_console_control cpkt;
 137
 138     stw_p(&cpkt.event, event);
 139     stw_p(&cpkt.value, value);
 140
 141     return send_control_msg(port, &cpkt, sizeof(cpkt));
 142 }
 143
 144 /* Functions for use inside qemu to open and read from/write to ports */
 145 int virtio_serial_open(VirtIOSerialPort *port)
 146 {
 147     /* Don't allow opening an already-open port */
 148     if (port->host_connected) {
 149         return 0;
 150     }
 151     /* Send port open notification to the guest */
 152     port->host_connected = true;
 153     send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
 154
 155     return 0;
 156 }
 157
 158 int virtio_serial_close(VirtIOSerialPort *port)
 159 {
 160     port->host_connected = false;
 161     send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
 162
 163     return 0;
 164 }
 165
 166 /* Individual ports/apps call this function to write to the guest. */
 167 ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
 168                             size_t size)
 169 {
 170     if (!port || !port->host_connected || !port->guest_connected) {
 171         return 0;
 172     }
 173     return write_to_port(port, buf, size);
 174 }
 175
 176 /*
 177  * Readiness of the guest to accept data on a port.
 178  * Returns max. data the guest can receive
 179  */
 180 size_t virtio_serial_guest_ready(VirtIOSerialPort *port)
 181 {
 182     VirtQueue *vq = port->ivq;
 183
 184     if (!virtio_queue_ready(vq) ||
 185         !(port->vser->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK) ||
 186         virtio_queue_empty(vq)) {
 187         return 0;
 188     }
 189     if (use_multiport(port->vser) && !port->guest_connected) {
 190         return 0;
 191     }
 192
 193     if (virtqueue_avail_bytes(vq, 4096, 0)) {
 194         return 4096;
 195     }
 196     if (virtqueue_avail_bytes(vq, 1, 0)) {
 197         return 1;
 198     }
 199     return 0;
 200 }
 201
 202 /* Guest wants to notify us of some event */
 203 static void handle_control_message(VirtIOSerial *vser, void *buf)
 204 {
 205     struct VirtIOSerialPort *port;
 206     struct virtio_console_control cpkt, *gcpkt;
 207     uint8_t *buffer;
 208     size_t buffer_len;
 209
 210     gcpkt = buf;
 211     port = find_port_by_id(vser, ldl_p(&gcpkt->id));
 212     if (!port)
 213         return;
 214
 215     cpkt.event = lduw_p(&gcpkt->event);
 216     cpkt.value = lduw_p(&gcpkt->value);
 217
 218     switch(cpkt.event) {
 219     case VIRTIO_CONSOLE_PORT_READY:
 220         /*
 221          * Now that we know the guest asked for the port name, we're
 222          * sure the guest has initialised whatever state is necessary
 223          * for this port. Now's a good time to let the guest know if
 224          * this port is a console port so that the guest can hook it
 225          * up to hvc.
 226          */
 227         if (port->is_console) {
 228             send_control_event(port, VIRTIO_CONSOLE_CONSOLE_PORT, 1);
 229         }
 230
 231         if (port->name) {
 232             stw_p(&cpkt.event, VIRTIO_CONSOLE_PORT_NAME);
 233             stw_p(&cpkt.value, 1);
 234
 235             buffer_len = sizeof(cpkt) + strlen(port->name) + 1;
 236             buffer = qemu_malloc(buffer_len);
 237
 238             memcpy(buffer, &cpkt, sizeof(cpkt));
 239             memcpy(buffer + sizeof(cpkt), port->name, strlen(port->name));
 240             buffer[buffer_len - 1] = 0;
 241
 242             send_control_msg(port, buffer, buffer_len);
 243             qemu_free(buffer);
 244         }
 245
 246         if (port->host_connected) {
 247             send_control_event(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
 248         }
 249
 250         /*
 251          * When the guest has asked us for this information it means
 252          * the guest is all setup and has its virtqueues
 253          * initialised. If some app is interested in knowing about
 254          * this event, let it know.
 255          */
 256         if (port->info->guest_ready) {
 257             port->info->guest_ready(port);
 258         }
 259         break;
 260
 261     case VIRTIO_CONSOLE_PORT_OPEN:
 262         port->guest_connected = cpkt.value;
 263         if (cpkt.value && port->info->guest_open) {
 264             /* Send the guest opened notification if an app is interested */
 265             port->info->guest_open(port);
 266         }
 267
 268         if (!cpkt.value && port->info->guest_close) {
 269             /* Send the guest closed notification if an app is interested */
 270             port->info->guest_close(port);
 271         }
 272         break;
 273     }
 274 }
 275
 276 static void control_in(VirtIODevice *vdev, VirtQueue *vq)
 277 {
 278 }
 279
 280 static void control_out(VirtIODevice *vdev, VirtQueue *vq)
 281 {
 282     VirtQueueElement elem;
 283     VirtIOSerial *vser;
 284
 285     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 286
 287     while (virtqueue_pop(vq, &elem)) {
 288         handle_control_message(vser, elem.out_sg[0].iov_base);
 289         virtqueue_push(vq, &elem, elem.out_sg[0].iov_len);
 290     }
 291     virtio_notify(vdev, vq);
 292 }
 293
 294 /* Guest wrote something to some port. */
 295 static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
 296 {
 297     VirtIOSerial *vser;
 298     VirtQueueElement elem;
 299
 300     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 301
 302     while (virtqueue_pop(vq, &elem)) {
 303         VirtIOSerialPort *port;
 304         size_t ret;
 305
 306         port = find_port_by_vq(vser, vq);
 307         if (!port) {
 308             ret = 0;
 309             goto next_buf;
 310         }
 311
 312         /*
 313          * A port may not have any handler registered for consuming the
 314          * data that the guest sends or it may not have a chardev associated
 315          * with it. Just ignore the data in that case.
 316          */
 317         if (!port->info->have_data) {
 318             ret = 0;
 319             goto next_buf;
 320         }
 321
 322         /* The guest always sends only one sg */
 323         ret = port->info->have_data(port, elem.out_sg[0].iov_base,
 324                                     elem.out_sg[0].iov_len);
 325
 326     next_buf:
 327         virtqueue_push(vq, &elem, ret);
 328     }
 329     virtio_notify(vdev, vq);
 330 }
 331
 332 static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
 333 {
 334 }
 335
 336 static uint32_t get_features(VirtIODevice *vdev, uint32_t features)
 337 {
 338     VirtIOSerial *vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 339     if (vser->bus->max_nr_ports > 1) {
 340         features |= (1 << VIRTIO_CONSOLE_F_MULTIPORT);
 341     }
 342     return features;
 343 }
 344
 345 /* Guest requested config info */
 346 static void get_config(VirtIODevice *vdev, uint8_t *config_data)
 347 {
 348     VirtIOSerial *vser;
 349
 350     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 351     memcpy(config_data, &vser->config, sizeof(struct virtio_console_config));
 352 }
 353
 354 static void set_config(VirtIODevice *vdev, const uint8_t *config_data)
 355 {
 356     struct virtio_console_config config;
 357
 358     memcpy(&config, config_data, sizeof(config));
 359 }
 360
 361 static void virtio_serial_save(QEMUFile *f, void *opaque)
 362 {
 363     VirtIOSerial *s = opaque;
 364     VirtIOSerialPort *port;
 365     uint32_t nr_active_ports;
 366
 367     /* The virtio device */
 368     virtio_save(&s->vdev, f);
 369
 370     /* The config space */
 371     qemu_put_be16s(f, &s->config.cols);
 372     qemu_put_be16s(f, &s->config.rows);
 373     qemu_put_be32s(f, &s->config.nr_ports);
 374
 375     /* Items in struct VirtIOSerial */
 376
 377     qemu_put_be32s(f, &s->bus->max_nr_ports);
 378
 379     /* Do this because we might have hot-unplugged some ports */
 380     nr_active_ports = 0;
 381     QTAILQ_FOREACH(port, &s->ports, next) {
 382         nr_active_ports++;
 383     }
 384
 385     qemu_put_be32s(f, &nr_active_ports);
 386
 387     /*
 388      * Items in struct VirtIOSerialPort.
 389      */
 390     QTAILQ_FOREACH(port, &s->ports, next) {
 391         /*
 392          * We put the port number because we may not have an active
 393          * port at id 0 that's reserved for a console port, or in case
 394          * of ports that might have gotten unplugged
 395          */
 396         qemu_put_be32s(f, &port->id);
 397         qemu_put_byte(f, port->guest_connected);
 398     }
 399 }
 400
 401 static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
 402 {
 403     VirtIOSerial *s = opaque;
 404     VirtIOSerialPort *port;
 405     uint32_t max_nr_ports, nr_active_ports, nr_ports;
 406     unsigned int i;
 407
 408     if (version_id > 2) {
 409         return -EINVAL;
 410     }
 411
 412     /* The virtio device */
 413     virtio_load(&s->vdev, f);
 414
 415     if (version_id < 2) {
 416         return 0;
 417     }
 418
 419     /* The config space */
 420     qemu_get_be16s(f, &s->config.cols);
 421     qemu_get_be16s(f, &s->config.rows);
 422     nr_ports = qemu_get_be32(f);
 423
 424     if (nr_ports != s->config.nr_ports) {
 425         /*
 426          * Source hot-plugged/unplugged ports and we don't have all of
 427          * them here.
 428          *
 429          * Note: This condition cannot check for all hotplug/unplug
 430          * events: eg, if one port was hot-plugged and one was
 431          * unplugged, the nr_ports remains the same but the port id's
 432          * would have changed and we won't catch it here. A later
 433          * check for !find_port_by_id() will confirm if this happened.
 434          */
 435         return -EINVAL;
 436     }
 437
 438     /* Items in struct VirtIOSerial */
 439
 440     qemu_get_be32s(f, &max_nr_ports);
 441     if (max_nr_ports > s->bus->max_nr_ports) {
 442         /* Source could have more ports than us. Fail migration. */
 443         return -EINVAL;
 444     }
 445
 446     qemu_get_be32s(f, &nr_active_ports);
 447
 448     /* Items in struct VirtIOSerialPort */
 449     for (i = 0; i < nr_active_ports; i++) {
 450         uint32_t id;
 451
 452         id = qemu_get_be32(f);
 453         port = find_port_by_id(s, id);
 454
 455         port->guest_connected = qemu_get_byte(f);
 456     }
 457
 458     return 0;
 459 }
 460
 461 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent);
 462
 463 static struct BusInfo virtser_bus_info = {
 464     .name      = "virtio-serial-bus",
 465     .size      = sizeof(VirtIOSerialBus),
 466     .print_dev = virtser_bus_dev_print,
 467 };
 468
 469 static VirtIOSerialBus *virtser_bus_new(DeviceState *dev)
 470 {
 471     VirtIOSerialBus *bus;
 472
 473     bus = FROM_QBUS(VirtIOSerialBus, qbus_create(&virtser_bus_info, dev, NULL));
 474     bus->qbus.allow_hotplug = 1;
 475
 476     return bus;
 477 }
 478
 479 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent)
 480 {
 481     VirtIOSerialDevice *dev = DO_UPCAST(VirtIOSerialDevice, qdev, qdev);
 482     VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, &dev->qdev);
 483
 484     monitor_printf(mon, "%*s dev-prop-int: id: %u\n",
 485                    indent, "", port->id);
 486     monitor_printf(mon, "%*s dev-prop-int: guest_connected: %d\n",
 487                    indent, "", port->guest_connected);
 488     monitor_printf(mon, "%*s dev-prop-int: host_connected: %d\n",
 489                    indent, "", port->host_connected);
 490 }
 491
 492 static int virtser_port_qdev_init(DeviceState *qdev, DeviceInfo *base)
 493 {
 494     VirtIOSerialDevice *dev = DO_UPCAST(VirtIOSerialDevice, qdev, qdev);
 495     VirtIOSerialPortInfo *info = DO_UPCAST(VirtIOSerialPortInfo, qdev, base);
 496     VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, &dev->qdev);
 497     VirtIOSerialBus *bus = DO_UPCAST(VirtIOSerialBus, qbus, qdev->parent_bus);
 498     int ret;
 499     bool plugging_port0;
 500
 501     port->vser = bus->vser;
 502
 503     /*
 504      * Is the first console port we're seeing? If so, put it up at
 505      * location 0. This is done for backward compatibility (old
 506      * kernel, new qemu).
 507      */
 508     plugging_port0 = port->is_console && !find_port_by_id(port->vser, 0);
 509
 510     if (port->vser->config.nr_ports == bus->max_nr_ports && !plugging_port0) {
 511         error_report("virtio-serial-bus: Maximum device limit reached");
 512         return -1;
 513     }
 514     dev->info = info;
 515
 516     ret = info->init(dev);
 517     if (ret) {
 518         return ret;
 519     }
 520
 521     port->id = plugging_port0 ? 0 : port->vser->config.nr_ports++;
 522
 523     if (!use_multiport(port->vser)) {
 524         /*
 525          * Allow writes to guest in this case; we have no way of
 526          * knowing if a guest port is connected.
 527          */
 528         port->guest_connected = true;
 529     }
 530
 531     QTAILQ_INSERT_TAIL(&port->vser->ports, port, next);
 532     port->ivq = port->vser->ivqs[port->id];
 533     port->ovq = port->vser->ovqs[port->id];
 534
 535     /* Send an update to the guest about this new port added */
 536     virtio_notify_config(&port->vser->vdev);
 537
 538     return ret;
 539 }
 540
 541 static int virtser_port_qdev_exit(DeviceState *qdev)
 542 {
 543     VirtIOSerialDevice *dev = DO_UPCAST(VirtIOSerialDevice, qdev, qdev);
 544     VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, &dev->qdev);
 545     VirtIOSerial *vser = port->vser;
 546
 547     send_control_event(port, VIRTIO_CONSOLE_PORT_REMOVE, 1);
 548
 549     /*
 550      * Don't decrement nr_ports here; thus we keep a linearly
 551      * increasing port id. Not utilising an id again saves us a couple
 552      * of complications:
 553      *
 554      * - Not having to bother about sending the port id to the guest
 555      *   kernel on hotplug or on addition of new ports; the guest can
 556      *   also linearly increment the port number. This is preferable
 557      *   because the config space won't have the need to store a
 558      *   ports_map.
 559      *
 560      * - Extra state to be stored for all the "holes" that got created
 561      *   so that we keep filling in the ids from the least available
 562      *   index.
 563      *
 564      * When such a functionality is desired, a control message to add
 565      * a port can be introduced.
 566      */
 567     QTAILQ_REMOVE(&vser->ports, port, next);
 568
 569     if (port->info->exit)
 570         port->info->exit(dev);
 571
 572     return 0;
 573 }
 574
 575 void virtio_serial_port_qdev_register(VirtIOSerialPortInfo *info)
 576 {
 577     info->qdev.init = virtser_port_qdev_init;
 578     info->qdev.bus_info = &virtser_bus_info;
 579     info->qdev.exit = virtser_port_qdev_exit;
 580     info->qdev.unplug = qdev_simple_unplug_cb;
 581     qdev_register(&info->qdev);
 582 }
 583
 584 VirtIODevice *virtio_serial_init(DeviceState *dev, uint32_t max_nr_ports)
 585 {
 586     VirtIOSerial *vser;
 587     VirtIODevice *vdev;
 588     uint32_t i;
 589
 590     if (!max_nr_ports)
 591         return NULL;
 592
 593     vdev = virtio_common_init("virtio-serial", VIRTIO_ID_CONSOLE,
 594                               sizeof(struct virtio_console_config),
 595                               sizeof(VirtIOSerial));
 596
 597     vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
 598
 599     /* Spawn a new virtio-serial bus on which the ports will ride as devices */
 600     vser->bus = virtser_bus_new(dev);
 601     vser->bus->vser = vser;
 602     QTAILQ_INIT(&vser->ports);
 603
 604     vser->bus->max_nr_ports = max_nr_ports;
 605     vser->ivqs = qemu_malloc(max_nr_ports * sizeof(VirtQueue *));
 606     vser->ovqs = qemu_malloc(max_nr_ports * sizeof(VirtQueue *));
 607
 608     /* Add a queue for host to guest transfers for port 0 (backward compat) */
 609     vser->ivqs[0] = virtio_add_queue(vdev, 128, handle_input);
 610     /* Add a queue for guest to host transfers for port 0 (backward compat) */
 611     vser->ovqs[0] = virtio_add_queue(vdev, 128, handle_output);
 612
 613     /* control queue: host to guest */
 614     vser->c_ivq = virtio_add_queue(vdev, 16, control_in);
 615     /* control queue: guest to host */
 616     vser->c_ovq = virtio_add_queue(vdev, 16, control_out);
 617
 618     for (i = 1; i < vser->bus->max_nr_ports; i++) {
 619         /* Add a per-port queue for host to guest transfers */
 620         vser->ivqs[i] = virtio_add_queue(vdev, 128, handle_input);
 621         /* Add a per-per queue for guest to host transfers */
 622         vser->ovqs[i] = virtio_add_queue(vdev, 128, handle_output);
 623     }
 624
 625     vser->config.max_nr_ports = max_nr_ports;
 626     /*
 627      * Reserve location 0 for a console port for backward compat
 628      * (old kernel, new qemu)
 629      */
 630     vser->config.nr_ports = 1;
 631
 632     vser->vdev.get_features = get_features;
 633     vser->vdev.get_config = get_config;
 634     vser->vdev.set_config = set_config;
 635
 636     /*
 637      * Register for the savevm section with the virtio-console name
 638      * to preserve backward compat
 639      */
 640     register_savevm("virtio-console", -1, 2, virtio_serial_save,
 641                     virtio_serial_load, vser);
 642
 643     return vdev;
 644 }