xref: /openbmc/qemu/hw/char/virtio-serial-bus.c (revision c2387413)
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 "qapi/error.h"
23 #include "qemu/iov.h"
24 #include "qemu/main-loop.h"
25 #include "qemu/module.h"
26 #include "migration/qemu-file-types.h"
27 #include "monitor/monitor.h"
28 #include "qemu/error-report.h"
29 #include "qemu/queue.h"
30 #include "hw/qdev-properties.h"
31 #include "hw/sysbus.h"
32 #include "trace.h"
33 #include "hw/virtio/virtio-serial.h"
34 #include "hw/virtio/virtio-access.h"
35 
36 static struct VirtIOSerialDevices {
37     QLIST_HEAD(, VirtIOSerial) devices;
38 } vserdevices;
39 
40 static VirtIOSerialPort *find_port_by_id(VirtIOSerial *vser, uint32_t id)
41 {
42     VirtIOSerialPort *port;
43 
44     if (id == VIRTIO_CONSOLE_BAD_ID) {
45         return NULL;
46     }
47 
48     QTAILQ_FOREACH(port, &vser->ports, next) {
49         if (port->id == id)
50             return port;
51     }
52     return NULL;
53 }
54 
55 static VirtIOSerialPort *find_port_by_vq(VirtIOSerial *vser, VirtQueue *vq)
56 {
57     VirtIOSerialPort *port;
58 
59     QTAILQ_FOREACH(port, &vser->ports, next) {
60         if (port->ivq == vq || port->ovq == vq)
61             return port;
62     }
63     return NULL;
64 }
65 
66 static VirtIOSerialPort *find_port_by_name(char *name)
67 {
68     VirtIOSerial *vser;
69 
70     QLIST_FOREACH(vser, &vserdevices.devices, next) {
71         VirtIOSerialPort *port;
72 
73         QTAILQ_FOREACH(port, &vser->ports, next) {
74             if (port->name && !strcmp(port->name, name)) {
75                 return port;
76             }
77         }
78     }
79     return NULL;
80 }
81 
82 static VirtIOSerialPort *find_first_connected_console(VirtIOSerial *vser)
83 {
84     VirtIOSerialPort *port;
85 
86     QTAILQ_FOREACH(port, &vser->ports, next) {
87         VirtIOSerialPortClass const *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
88         if (vsc->is_console && port->host_connected) {
89             return port;
90         }
91     }
92     return NULL;
93 }
94 
95 static bool use_multiport(VirtIOSerial *vser)
96 {
97     VirtIODevice *vdev = VIRTIO_DEVICE(vser);
98     return virtio_vdev_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT);
99 }
100 
101 static size_t write_to_port(VirtIOSerialPort *port,
102                             const uint8_t *buf, size_t size)
103 {
104     VirtQueueElement *elem;
105     VirtQueue *vq;
106     size_t offset;
107 
108     vq = port->ivq;
109     if (!virtio_queue_ready(vq)) {
110         return 0;
111     }
112 
113     offset = 0;
114     while (offset < size) {
115         size_t len;
116 
117         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
118         if (!elem) {
119             break;
120         }
121 
122         len = iov_from_buf(elem->in_sg, elem->in_num, 0,
123                            buf + offset, size - offset);
124         offset += len;
125 
126         virtqueue_push(vq, elem, len);
127         g_free(elem);
128     }
129 
130     virtio_notify(VIRTIO_DEVICE(port->vser), vq);
131     return offset;
132 }
133 
134 static void discard_vq_data(VirtQueue *vq, VirtIODevice *vdev)
135 {
136     VirtQueueElement *elem;
137 
138     if (!virtio_queue_ready(vq)) {
139         return;
140     }
141     for (;;) {
142         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
143         if (!elem) {
144             break;
145         }
146         virtqueue_push(vq, elem, 0);
147         g_free(elem);
148     }
149     virtio_notify(vdev, vq);
150 }
151 
152 static void discard_throttle_data(VirtIOSerialPort *port)
153 {
154     if (port->elem) {
155         virtqueue_detach_element(port->ovq, port->elem, 0);
156         g_free(port->elem);
157         port->elem = NULL;
158     }
159 }
160 
161 static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq,
162                                  VirtIODevice *vdev)
163 {
164     VirtIOSerialPortClass *vsc;
165 
166     assert(port);
167     assert(virtio_queue_ready(vq));
168 
169     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
170 
171     while (!port->throttled) {
172         unsigned int i;
173 
174         /* Pop an elem only if we haven't left off a previous one mid-way */
175         if (!port->elem) {
176             port->elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
177             if (!port->elem) {
178                 break;
179             }
180             port->iov_idx = 0;
181             port->iov_offset = 0;
182         }
183 
184         for (i = port->iov_idx; i < port->elem->out_num; i++) {
185             size_t buf_size;
186             ssize_t ret;
187 
188             buf_size = port->elem->out_sg[i].iov_len - port->iov_offset;
189             ret = vsc->have_data(port,
190                                   port->elem->out_sg[i].iov_base
191                                   + port->iov_offset,
192                                   buf_size);
193             if (!port->elem) { /* bail if we got disconnected */
194                 return;
195             }
196             if (port->throttled) {
197                 port->iov_idx = i;
198                 if (ret > 0) {
199                     port->iov_offset += ret;
200                 }
201                 break;
202             }
203             port->iov_offset = 0;
204         }
205         if (port->throttled) {
206             break;
207         }
208         virtqueue_push(vq, port->elem, 0);
209         g_free(port->elem);
210         port->elem = NULL;
211     }
212     virtio_notify(vdev, vq);
213 }
214 
215 static void flush_queued_data(VirtIOSerialPort *port)
216 {
217     assert(port);
218 
219     if (!virtio_queue_ready(port->ovq)) {
220         return;
221     }
222     do_flush_queued_data(port, port->ovq, VIRTIO_DEVICE(port->vser));
223 }
224 
225 static size_t send_control_msg(VirtIOSerial *vser, void *buf, size_t len)
226 {
227     VirtQueueElement *elem;
228     VirtQueue *vq;
229 
230     vq = vser->c_ivq;
231     if (!virtio_queue_ready(vq)) {
232         return 0;
233     }
234 
235     elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
236     if (!elem) {
237         return 0;
238     }
239 
240     /* TODO: detect a buffer that's too short, set NEEDS_RESET */
241     iov_from_buf(elem->in_sg, elem->in_num, 0, buf, len);
242 
243     virtqueue_push(vq, elem, len);
244     virtio_notify(VIRTIO_DEVICE(vser), vq);
245     g_free(elem);
246 
247     return len;
248 }
249 
250 static size_t send_control_event(VirtIOSerial *vser, uint32_t port_id,
251                                  uint16_t event, uint16_t value)
252 {
253     VirtIODevice *vdev = VIRTIO_DEVICE(vser);
254     struct virtio_console_control cpkt;
255 
256     virtio_stl_p(vdev, &cpkt.id, port_id);
257     virtio_stw_p(vdev, &cpkt.event, event);
258     virtio_stw_p(vdev, &cpkt.value, value);
259 
260     trace_virtio_serial_send_control_event(port_id, event, value);
261     return send_control_msg(vser, &cpkt, sizeof(cpkt));
262 }
263 
264 /* Functions for use inside qemu to open and read from/write to ports */
265 int virtio_serial_open(VirtIOSerialPort *port)
266 {
267     /* Don't allow opening an already-open port */
268     if (port->host_connected) {
269         return 0;
270     }
271     /* Send port open notification to the guest */
272     port->host_connected = true;
273     send_control_event(port->vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 1);
274 
275     return 0;
276 }
277 
278 int virtio_serial_close(VirtIOSerialPort *port)
279 {
280     port->host_connected = false;
281     /*
282      * If there's any data the guest sent which the app didn't
283      * consume, reset the throttling flag and discard the data.
284      */
285     port->throttled = false;
286     discard_throttle_data(port);
287     discard_vq_data(port->ovq, VIRTIO_DEVICE(port->vser));
288 
289     send_control_event(port->vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 0);
290 
291     return 0;
292 }
293 
294 /* Individual ports/apps call this function to write to the guest. */
295 ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
296                             size_t size)
297 {
298     if (!port || !port->host_connected || !port->guest_connected) {
299         return 0;
300     }
301     return write_to_port(port, buf, size);
302 }
303 
304 /*
305  * Readiness of the guest to accept data on a port.
306  * Returns max. data the guest can receive
307  */
308 size_t virtio_serial_guest_ready(VirtIOSerialPort *port)
309 {
310     VirtIODevice *vdev = VIRTIO_DEVICE(port->vser);
311     VirtQueue *vq = port->ivq;
312     unsigned int bytes;
313 
314     if (!virtio_queue_ready(vq) ||
315         !(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) ||
316         virtio_queue_empty(vq)) {
317         return 0;
318     }
319     if (use_multiport(port->vser) && !port->guest_connected) {
320         return 0;
321     }
322     virtqueue_get_avail_bytes(vq, &bytes, NULL, 4096, 0);
323     return bytes;
324 }
325 
326 static void flush_queued_data_bh(void *opaque)
327 {
328     VirtIOSerialPort *port = opaque;
329 
330     flush_queued_data(port);
331 }
332 
333 void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle)
334 {
335     if (!port) {
336         return;
337     }
338 
339     trace_virtio_serial_throttle_port(port->id, throttle);
340     port->throttled = throttle;
341     if (throttle) {
342         return;
343     }
344     qemu_bh_schedule(port->bh);
345 }
346 
347 /* Guest wants to notify us of some event */
348 static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len)
349 {
350     VirtIODevice *vdev = VIRTIO_DEVICE(vser);
351     struct VirtIOSerialPort *port;
352     VirtIOSerialPortClass *vsc;
353     struct virtio_console_control cpkt, *gcpkt;
354     uint8_t *buffer;
355     size_t buffer_len;
356 
357     gcpkt = buf;
358 
359     if (len < sizeof(cpkt)) {
360         /* The guest sent an invalid control packet */
361         return;
362     }
363 
364     cpkt.event = virtio_lduw_p(vdev, &gcpkt->event);
365     cpkt.value = virtio_lduw_p(vdev, &gcpkt->value);
366 
367     trace_virtio_serial_handle_control_message(cpkt.event, cpkt.value);
368 
369     if (cpkt.event == VIRTIO_CONSOLE_DEVICE_READY) {
370         if (!cpkt.value) {
371             error_report("virtio-serial-bus: Guest failure in adding device %s",
372                          vser->bus.qbus.name);
373             return;
374         }
375         /*
376          * The device is up, we can now tell the device about all the
377          * ports we have here.
378          */
379         QTAILQ_FOREACH(port, &vser->ports, next) {
380             send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_ADD, 1);
381         }
382         return;
383     }
384 
385     port = find_port_by_id(vser, virtio_ldl_p(vdev, &gcpkt->id));
386     if (!port) {
387         error_report("virtio-serial-bus: Unexpected port id %u for device %s",
388                      virtio_ldl_p(vdev, &gcpkt->id), vser->bus.qbus.name);
389         return;
390     }
391 
392     trace_virtio_serial_handle_control_message_port(port->id);
393 
394     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
395 
396     switch(cpkt.event) {
397     case VIRTIO_CONSOLE_PORT_READY:
398         if (!cpkt.value) {
399             error_report("virtio-serial-bus: Guest failure in adding port %u for device %s",
400                          port->id, vser->bus.qbus.name);
401             break;
402         }
403         /*
404          * Now that we know the guest asked for the port name, we're
405          * sure the guest has initialised whatever state is necessary
406          * for this port. Now's a good time to let the guest know if
407          * this port is a console port so that the guest can hook it
408          * up to hvc.
409          */
410         if (vsc->is_console) {
411             send_control_event(vser, port->id, VIRTIO_CONSOLE_CONSOLE_PORT, 1);
412         }
413 
414         if (port->name) {
415             virtio_stl_p(vdev, &cpkt.id, port->id);
416             virtio_stw_p(vdev, &cpkt.event, VIRTIO_CONSOLE_PORT_NAME);
417             virtio_stw_p(vdev, &cpkt.value, 1);
418 
419             buffer_len = sizeof(cpkt) + strlen(port->name) + 1;
420             buffer = g_malloc(buffer_len);
421 
422             memcpy(buffer, &cpkt, sizeof(cpkt));
423             memcpy(buffer + sizeof(cpkt), port->name, strlen(port->name));
424             buffer[buffer_len - 1] = 0;
425 
426             send_control_msg(vser, buffer, buffer_len);
427             g_free(buffer);
428         }
429 
430         if (port->host_connected) {
431             send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_OPEN, 1);
432         }
433 
434         /*
435          * When the guest has asked us for this information it means
436          * the guest is all setup and has its virtqueues
437          * initialised. If some app is interested in knowing about
438          * this event, let it know.
439          */
440         if (vsc->guest_ready) {
441             vsc->guest_ready(port);
442         }
443         break;
444 
445     case VIRTIO_CONSOLE_PORT_OPEN:
446         port->guest_connected = cpkt.value;
447         if (vsc->set_guest_connected) {
448             /* Send the guest opened notification if an app is interested */
449             vsc->set_guest_connected(port, cpkt.value);
450         }
451         break;
452     }
453 }
454 
455 static void control_in(VirtIODevice *vdev, VirtQueue *vq)
456 {
457 }
458 
459 static void control_out(VirtIODevice *vdev, VirtQueue *vq)
460 {
461     VirtQueueElement *elem;
462     VirtIOSerial *vser;
463     uint8_t *buf;
464     size_t len;
465 
466     vser = VIRTIO_SERIAL(vdev);
467 
468     len = 0;
469     buf = NULL;
470     for (;;) {
471         size_t cur_len;
472 
473         elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
474         if (!elem) {
475             break;
476         }
477 
478         cur_len = iov_size(elem->out_sg, elem->out_num);
479         /*
480          * Allocate a new buf only if we didn't have one previously or
481          * if the size of the buf differs
482          */
483         if (cur_len > len) {
484             g_free(buf);
485 
486             buf = g_malloc(cur_len);
487             len = cur_len;
488         }
489         iov_to_buf(elem->out_sg, elem->out_num, 0, buf, cur_len);
490 
491         handle_control_message(vser, buf, cur_len);
492         virtqueue_push(vq, elem, 0);
493         g_free(elem);
494     }
495     g_free(buf);
496     virtio_notify(vdev, vq);
497 }
498 
499 /* Guest wrote something to some port. */
500 static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
501 {
502     VirtIOSerial *vser;
503     VirtIOSerialPort *port;
504 
505     vser = VIRTIO_SERIAL(vdev);
506     port = find_port_by_vq(vser, vq);
507 
508     if (!port || !port->host_connected) {
509         discard_vq_data(vq, vdev);
510         return;
511     }
512 
513     if (!port->throttled) {
514         do_flush_queued_data(port, vq, vdev);
515         return;
516     }
517 }
518 
519 static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
520 {
521     /*
522      * Users of virtio-serial would like to know when guest becomes
523      * writable again -- i.e. if a vq had stuff queued up and the
524      * guest wasn't reading at all, the host would not be able to
525      * write to the vq anymore.  Once the guest reads off something,
526      * we can start queueing things up again.  However, this call is
527      * made for each buffer addition by the guest -- even though free
528      * buffers existed prior to the current buffer addition.  This is
529      * done so as not to maintain previous state, which will need
530      * additional live-migration-related changes.
531      */
532     VirtIOSerial *vser;
533     VirtIOSerialPort *port;
534     VirtIOSerialPortClass *vsc;
535 
536     vser = VIRTIO_SERIAL(vdev);
537     port = find_port_by_vq(vser, vq);
538 
539     if (!port) {
540         return;
541     }
542     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
543 
544     /*
545      * If guest_connected is false, this call is being made by the
546      * early-boot queueing up of descriptors, which is just noise for
547      * the host apps -- don't disturb them in that case.
548      */
549     if (port->guest_connected && port->host_connected && vsc->guest_writable) {
550         vsc->guest_writable(port);
551     }
552 }
553 
554 static uint64_t get_features(VirtIODevice *vdev, uint64_t features,
555                              Error **errp)
556 {
557     VirtIOSerial *vser;
558 
559     vser = VIRTIO_SERIAL(vdev);
560 
561     features |= vser->host_features;
562     if (vser->bus.max_nr_ports > 1) {
563         virtio_add_feature(&features, VIRTIO_CONSOLE_F_MULTIPORT);
564     }
565     return features;
566 }
567 
568 /* Guest requested config info */
569 static void get_config(VirtIODevice *vdev, uint8_t *config_data)
570 {
571     VirtIOSerial *vser = VIRTIO_SERIAL(vdev);
572     struct virtio_console_config *config =
573         (struct virtio_console_config *)config_data;
574 
575     config->cols = 0;
576     config->rows = 0;
577     config->max_nr_ports = virtio_tswap32(vdev,
578                                           vser->serial.max_virtserial_ports);
579 }
580 
581 /* Guest sent new config info */
582 static void set_config(VirtIODevice *vdev, const uint8_t *config_data)
583 {
584     VirtIOSerial *vser = VIRTIO_SERIAL(vdev);
585     struct virtio_console_config *config =
586         (struct virtio_console_config *)config_data;
587     VirtIOSerialPort *port = find_first_connected_console(vser);
588     VirtIOSerialPortClass *vsc;
589     uint8_t emerg_wr_lo;
590 
591     if (!virtio_has_feature(vser->host_features,
592         VIRTIO_CONSOLE_F_EMERG_WRITE) || !config->emerg_wr) {
593         return;
594     }
595 
596     emerg_wr_lo = le32_to_cpu(config->emerg_wr);
597     /* Make sure we don't misdetect an emergency write when the guest
598      * does a short config write after an emergency write. */
599     config->emerg_wr = 0;
600     if (!port) {
601         return;
602     }
603     vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
604     (void)vsc->have_data(port, &emerg_wr_lo, 1);
605 }
606 
607 static void guest_reset(VirtIOSerial *vser)
608 {
609     VirtIOSerialPort *port;
610     VirtIOSerialPortClass *vsc;
611 
612     QTAILQ_FOREACH(port, &vser->ports, next) {
613         vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
614 
615         discard_throttle_data(port);
616 
617         if (port->guest_connected) {
618             port->guest_connected = false;
619             if (vsc->set_guest_connected) {
620                 vsc->set_guest_connected(port, false);
621             }
622         }
623     }
624 }
625 
626 static void set_status(VirtIODevice *vdev, uint8_t status)
627 {
628     VirtIOSerial *vser;
629     VirtIOSerialPort *port;
630 
631     vser = VIRTIO_SERIAL(vdev);
632     port = find_port_by_id(vser, 0);
633 
634     if (port && !use_multiport(port->vser)
635         && (status & VIRTIO_CONFIG_S_DRIVER_OK)) {
636         /*
637          * Non-multiport guests won't be able to tell us guest
638          * open/close status.  Such guests can only have a port at id
639          * 0, so set guest_connected for such ports as soon as guest
640          * is up.
641          */
642         port->guest_connected = true;
643     }
644     if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
645         guest_reset(vser);
646     }
647 
648     QTAILQ_FOREACH(port, &vser->ports, next) {
649         VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
650         if (vsc->enable_backend) {
651             vsc->enable_backend(port, vdev->vm_running);
652         }
653     }
654 }
655 
656 static void vser_reset(VirtIODevice *vdev)
657 {
658     VirtIOSerial *vser;
659 
660     vser = VIRTIO_SERIAL(vdev);
661     guest_reset(vser);
662 }
663 
664 static void virtio_serial_save_device(VirtIODevice *vdev, QEMUFile *f)
665 {
666     VirtIOSerial *s = VIRTIO_SERIAL(vdev);
667     VirtIOSerialPort *port;
668     uint32_t nr_active_ports;
669     unsigned int i, max_nr_ports;
670     struct virtio_console_config config;
671 
672     /* The config space (ignored on the far end in current versions) */
673     get_config(vdev, (uint8_t *)&config);
674     qemu_put_be16(f, config.cols);
675     qemu_put_be16(f, config.rows);
676     qemu_put_be32(f, config.max_nr_ports);
677 
678     /* The ports map */
679     max_nr_ports = s->serial.max_virtserial_ports;
680     for (i = 0; i < DIV_ROUND_UP(max_nr_ports, 32); i++) {
681         qemu_put_be32s(f, &s->ports_map[i]);
682     }
683 
684     /* Ports */
685 
686     nr_active_ports = 0;
687     QTAILQ_FOREACH(port, &s->ports, next) {
688         nr_active_ports++;
689     }
690 
691     qemu_put_be32s(f, &nr_active_ports);
692 
693     /*
694      * Items in struct VirtIOSerialPort.
695      */
696     QTAILQ_FOREACH(port, &s->ports, next) {
697         uint32_t elem_popped;
698 
699         qemu_put_be32s(f, &port->id);
700         qemu_put_byte(f, port->guest_connected);
701         qemu_put_byte(f, port->host_connected);
702 
703         elem_popped = 0;
704         if (port->elem) {
705             elem_popped = 1;
706         }
707         qemu_put_be32s(f, &elem_popped);
708         if (elem_popped) {
709             qemu_put_be32s(f, &port->iov_idx);
710             qemu_put_be64s(f, &port->iov_offset);
711             qemu_put_virtqueue_element(vdev, f, port->elem);
712         }
713     }
714 }
715 
716 static void virtio_serial_post_load_timer_cb(void *opaque)
717 {
718     uint32_t i;
719     VirtIOSerial *s = VIRTIO_SERIAL(opaque);
720     VirtIOSerialPort *port;
721     uint8_t host_connected;
722     VirtIOSerialPortClass *vsc;
723 
724     if (!s->post_load) {
725         return;
726     }
727     for (i = 0 ; i < s->post_load->nr_active_ports; ++i) {
728         port = s->post_load->connected[i].port;
729         host_connected = s->post_load->connected[i].host_connected;
730         if (host_connected != port->host_connected) {
731             /*
732              * We have to let the guest know of the host connection
733              * status change
734              */
735             send_control_event(s, port->id, VIRTIO_CONSOLE_PORT_OPEN,
736                                port->host_connected);
737         }
738         vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
739         if (vsc->set_guest_connected) {
740             vsc->set_guest_connected(port, port->guest_connected);
741         }
742     }
743     g_free(s->post_load->connected);
744     timer_free(s->post_load->timer);
745     g_free(s->post_load);
746     s->post_load = NULL;
747 }
748 
749 static int fetch_active_ports_list(QEMUFile *f,
750                                    VirtIOSerial *s, uint32_t nr_active_ports)
751 {
752     VirtIODevice *vdev = VIRTIO_DEVICE(s);
753     uint32_t i;
754 
755     s->post_load = g_malloc0(sizeof(*s->post_load));
756     s->post_load->nr_active_ports = nr_active_ports;
757     s->post_load->connected =
758         g_malloc0(sizeof(*s->post_load->connected) * nr_active_ports);
759 
760     s->post_load->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
761                                             virtio_serial_post_load_timer_cb,
762                                             s);
763 
764     /* Items in struct VirtIOSerialPort */
765     for (i = 0; i < nr_active_ports; i++) {
766         VirtIOSerialPort *port;
767         uint32_t elem_popped;
768         uint32_t id;
769 
770         id = qemu_get_be32(f);
771         port = find_port_by_id(s, id);
772         if (!port) {
773             return -EINVAL;
774         }
775 
776         port->guest_connected = qemu_get_byte(f);
777         s->post_load->connected[i].port = port;
778         s->post_load->connected[i].host_connected = qemu_get_byte(f);
779 
780         qemu_get_be32s(f, &elem_popped);
781         if (elem_popped) {
782             qemu_get_be32s(f, &port->iov_idx);
783             qemu_get_be64s(f, &port->iov_offset);
784 
785             port->elem =
786                 qemu_get_virtqueue_element(vdev, f, sizeof(VirtQueueElement));
787 
788             /*
789              *  Port was throttled on source machine.  Let's
790              *  unthrottle it here so data starts flowing again.
791              */
792             virtio_serial_throttle_port(port, false);
793         }
794     }
795     timer_mod(s->post_load->timer, 1);
796     return 0;
797 }
798 
799 static int virtio_serial_load_device(VirtIODevice *vdev, QEMUFile *f,
800                                      int version_id)
801 {
802     VirtIOSerial *s = VIRTIO_SERIAL(vdev);
803     uint32_t max_nr_ports, nr_active_ports, ports_map;
804     unsigned int i;
805     int ret;
806     uint32_t tmp;
807 
808     /* Unused */
809     qemu_get_be16s(f, (uint16_t *) &tmp);
810     qemu_get_be16s(f, (uint16_t *) &tmp);
811     qemu_get_be32s(f, &tmp);
812 
813     max_nr_ports = s->serial.max_virtserial_ports;
814     for (i = 0; i < DIV_ROUND_UP(max_nr_ports, 32); i++) {
815         qemu_get_be32s(f, &ports_map);
816 
817         if (ports_map != s->ports_map[i]) {
818             /*
819              * Ports active on source and destination don't
820              * match. Fail migration.
821              */
822             return -EINVAL;
823         }
824     }
825 
826     qemu_get_be32s(f, &nr_active_ports);
827 
828     if (nr_active_ports) {
829         ret = fetch_active_ports_list(f, s, nr_active_ports);
830         if (ret) {
831             return ret;
832         }
833     }
834     return 0;
835 }
836 
837 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent);
838 
839 static Property virtser_props[] = {
840     DEFINE_PROP_UINT32("nr", VirtIOSerialPort, id, VIRTIO_CONSOLE_BAD_ID),
841     DEFINE_PROP_STRING("name", VirtIOSerialPort, name),
842     DEFINE_PROP_END_OF_LIST()
843 };
844 
845 static void virtser_bus_class_init(ObjectClass *klass, void *data)
846 {
847     BusClass *k = BUS_CLASS(klass);
848     k->print_dev = virtser_bus_dev_print;
849 }
850 
851 static const TypeInfo virtser_bus_info = {
852     .name = TYPE_VIRTIO_SERIAL_BUS,
853     .parent = TYPE_BUS,
854     .instance_size = sizeof(VirtIOSerialBus),
855     .class_init = virtser_bus_class_init,
856 };
857 
858 static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent)
859 {
860     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(qdev);
861 
862     monitor_printf(mon, "%*sport %d, guest %s, host %s, throttle %s\n",
863                    indent, "", port->id,
864                    port->guest_connected ? "on" : "off",
865                    port->host_connected ? "on" : "off",
866                    port->throttled ? "on" : "off");
867 }
868 
869 /* This function is only used if a port id is not provided by the user */
870 static uint32_t find_free_port_id(VirtIOSerial *vser)
871 {
872     unsigned int i, max_nr_ports;
873 
874     max_nr_ports = vser->serial.max_virtserial_ports;
875     for (i = 0; i < DIV_ROUND_UP(max_nr_ports, 32); i++) {
876         uint32_t map, zeroes;
877 
878         map = vser->ports_map[i];
879         zeroes = ctz32(~map);
880         if (zeroes != 32) {
881             return zeroes + i * 32;
882         }
883     }
884     return VIRTIO_CONSOLE_BAD_ID;
885 }
886 
887 static void mark_port_added(VirtIOSerial *vser, uint32_t port_id)
888 {
889     unsigned int i;
890 
891     i = port_id / 32;
892     vser->ports_map[i] |= 1U << (port_id % 32);
893 }
894 
895 static void add_port(VirtIOSerial *vser, uint32_t port_id)
896 {
897     mark_port_added(vser, port_id);
898     send_control_event(vser, port_id, VIRTIO_CONSOLE_PORT_ADD, 1);
899 }
900 
901 static void remove_port(VirtIOSerial *vser, uint32_t port_id)
902 {
903     VirtIOSerialPort *port;
904 
905     /*
906      * Don't mark port 0 removed -- we explicitly reserve it for
907      * backward compat with older guests, ensure a virtconsole device
908      * unplug retains the reservation.
909      */
910     if (port_id) {
911         unsigned int i;
912 
913         i = port_id / 32;
914         vser->ports_map[i] &= ~(1U << (port_id % 32));
915     }
916 
917     port = find_port_by_id(vser, port_id);
918     /*
919      * This function is only called from qdev's unplug callback; if we
920      * get a NULL port here, we're in trouble.
921      */
922     assert(port);
923 
924     /* Flush out any unconsumed buffers first */
925     discard_throttle_data(port);
926     discard_vq_data(port->ovq, VIRTIO_DEVICE(port->vser));
927 
928     send_control_event(vser, port->id, VIRTIO_CONSOLE_PORT_REMOVE, 1);
929 }
930 
931 static void virtser_port_device_realize(DeviceState *dev, Error **errp)
932 {
933     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
934     VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
935     VirtIOSerialBus *bus = VIRTIO_SERIAL_BUS(qdev_get_parent_bus(dev));
936     int max_nr_ports;
937     bool plugging_port0;
938     Error *err = NULL;
939 
940     port->vser = bus->vser;
941 
942     assert(vsc->have_data);
943 
944     /*
945      * Is the first console port we're seeing? If so, put it up at
946      * location 0. This is done for backward compatibility (old
947      * kernel, new qemu).
948      */
949     plugging_port0 = vsc->is_console && !find_port_by_id(port->vser, 0);
950 
951     if (find_port_by_id(port->vser, port->id)) {
952         error_setg(errp, "virtio-serial-bus: A port already exists at id %u",
953                    port->id);
954         return;
955     }
956 
957     if (port->name != NULL && find_port_by_name(port->name)) {
958         error_setg(errp, "virtio-serial-bus: A port already exists by name %s",
959                    port->name);
960         return;
961     }
962 
963     if (port->id == VIRTIO_CONSOLE_BAD_ID) {
964         if (plugging_port0) {
965             port->id = 0;
966         } else {
967             port->id = find_free_port_id(port->vser);
968             if (port->id == VIRTIO_CONSOLE_BAD_ID) {
969                 error_setg(errp, "virtio-serial-bus: Maximum port limit for "
970                                  "this device reached");
971                 return;
972             }
973         }
974     }
975 
976     max_nr_ports = port->vser->serial.max_virtserial_ports;
977     if (port->id >= max_nr_ports) {
978         error_setg(errp, "virtio-serial-bus: Out-of-range port id specified, "
979                          "max. allowed: %u", max_nr_ports - 1);
980         return;
981     }
982 
983     vsc->realize(dev, &err);
984     if (err != NULL) {
985         error_propagate(errp, err);
986         return;
987     }
988 
989     port->bh = qemu_bh_new(flush_queued_data_bh, port);
990     port->elem = NULL;
991 }
992 
993 static void virtser_port_device_plug(HotplugHandler *hotplug_dev,
994                                      DeviceState *dev, Error **errp)
995 {
996     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
997 
998     QTAILQ_INSERT_TAIL(&port->vser->ports, port, next);
999     port->ivq = port->vser->ivqs[port->id];
1000     port->ovq = port->vser->ovqs[port->id];
1001 
1002     add_port(port->vser, port->id);
1003 
1004     /* Send an update to the guest about this new port added */
1005     virtio_notify_config(VIRTIO_DEVICE(hotplug_dev));
1006 }
1007 
1008 static void virtser_port_device_unrealize(DeviceState *dev)
1009 {
1010     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
1011     VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(dev);
1012     VirtIOSerial *vser = port->vser;
1013 
1014     qemu_bh_delete(port->bh);
1015     remove_port(port->vser, port->id);
1016 
1017     QTAILQ_REMOVE(&vser->ports, port, next);
1018 
1019     if (vsc->unrealize) {
1020         vsc->unrealize(dev);
1021     }
1022 }
1023 
1024 static void virtio_serial_device_realize(DeviceState *dev, Error **errp)
1025 {
1026     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
1027     VirtIOSerial *vser = VIRTIO_SERIAL(dev);
1028     uint32_t i, max_supported_ports;
1029     size_t config_size = sizeof(struct virtio_console_config);
1030 
1031     if (!vser->serial.max_virtserial_ports) {
1032         error_setg(errp, "Maximum number of serial ports not specified");
1033         return;
1034     }
1035 
1036     /* Each port takes 2 queues, and one pair is for the control queue */
1037     max_supported_ports = VIRTIO_QUEUE_MAX / 2 - 1;
1038 
1039     if (vser->serial.max_virtserial_ports > max_supported_ports) {
1040         error_setg(errp, "maximum ports supported: %u", max_supported_ports);
1041         return;
1042     }
1043 
1044     if (!virtio_has_feature(vser->host_features,
1045                             VIRTIO_CONSOLE_F_EMERG_WRITE)) {
1046         config_size = offsetof(struct virtio_console_config, emerg_wr);
1047     }
1048     virtio_init(vdev, "virtio-serial", VIRTIO_ID_CONSOLE,
1049                 config_size);
1050 
1051     /* Spawn a new virtio-serial bus on which the ports will ride as devices */
1052     qbus_create_inplace(&vser->bus, sizeof(vser->bus), TYPE_VIRTIO_SERIAL_BUS,
1053                         dev, vdev->bus_name);
1054     qbus_set_hotplug_handler(BUS(&vser->bus), OBJECT(vser));
1055     vser->bus.vser = vser;
1056     QTAILQ_INIT(&vser->ports);
1057 
1058     vser->bus.max_nr_ports = vser->serial.max_virtserial_ports;
1059     vser->ivqs = g_malloc(vser->serial.max_virtserial_ports
1060                           * sizeof(VirtQueue *));
1061     vser->ovqs = g_malloc(vser->serial.max_virtserial_ports
1062                           * sizeof(VirtQueue *));
1063 
1064     /* Add a queue for host to guest transfers for port 0 (backward compat) */
1065     vser->ivqs[0] = virtio_add_queue(vdev, 128, handle_input);
1066     /* Add a queue for guest to host transfers for port 0 (backward compat) */
1067     vser->ovqs[0] = virtio_add_queue(vdev, 128, handle_output);
1068 
1069     /* TODO: host to guest notifications can get dropped
1070      * if the queue fills up. Implement queueing in host,
1071      * this might also make it possible to reduce the control
1072      * queue size: as guest preposts buffers there,
1073      * this will save 4Kbyte of guest memory per entry. */
1074 
1075     /* control queue: host to guest */
1076     vser->c_ivq = virtio_add_queue(vdev, 32, control_in);
1077     /* control queue: guest to host */
1078     vser->c_ovq = virtio_add_queue(vdev, 32, control_out);
1079 
1080     for (i = 1; i < vser->bus.max_nr_ports; i++) {
1081         /* Add a per-port queue for host to guest transfers */
1082         vser->ivqs[i] = virtio_add_queue(vdev, 128, handle_input);
1083         /* Add a per-per queue for guest to host transfers */
1084         vser->ovqs[i] = virtio_add_queue(vdev, 128, handle_output);
1085     }
1086 
1087     vser->ports_map = g_malloc0((DIV_ROUND_UP(vser->serial.max_virtserial_ports, 32))
1088         * sizeof(vser->ports_map[0]));
1089     /*
1090      * Reserve location 0 for a console port for backward compat
1091      * (old kernel, new qemu)
1092      */
1093     mark_port_added(vser, 0);
1094 
1095     vser->post_load = NULL;
1096 
1097     QLIST_INSERT_HEAD(&vserdevices.devices, vser, next);
1098 }
1099 
1100 static void virtio_serial_port_class_init(ObjectClass *klass, void *data)
1101 {
1102     DeviceClass *k = DEVICE_CLASS(klass);
1103 
1104     set_bit(DEVICE_CATEGORY_INPUT, k->categories);
1105     k->bus_type = TYPE_VIRTIO_SERIAL_BUS;
1106     k->realize = virtser_port_device_realize;
1107     k->unrealize = virtser_port_device_unrealize;
1108     device_class_set_props(k, virtser_props);
1109 }
1110 
1111 static const TypeInfo virtio_serial_port_type_info = {
1112     .name = TYPE_VIRTIO_SERIAL_PORT,
1113     .parent = TYPE_DEVICE,
1114     .instance_size = sizeof(VirtIOSerialPort),
1115     .abstract = true,
1116     .class_size = sizeof(VirtIOSerialPortClass),
1117     .class_init = virtio_serial_port_class_init,
1118 };
1119 
1120 static void virtio_serial_device_unrealize(DeviceState *dev)
1121 {
1122     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
1123     VirtIOSerial *vser = VIRTIO_SERIAL(dev);
1124     int i;
1125 
1126     QLIST_REMOVE(vser, next);
1127 
1128     virtio_delete_queue(vser->c_ivq);
1129     virtio_delete_queue(vser->c_ovq);
1130     for (i = 0; i < vser->bus.max_nr_ports; i++) {
1131         virtio_delete_queue(vser->ivqs[i]);
1132         virtio_delete_queue(vser->ovqs[i]);
1133     }
1134 
1135     g_free(vser->ivqs);
1136     g_free(vser->ovqs);
1137     g_free(vser->ports_map);
1138     if (vser->post_load) {
1139         g_free(vser->post_load->connected);
1140         timer_free(vser->post_load->timer);
1141         g_free(vser->post_load);
1142     }
1143 
1144     qbus_set_hotplug_handler(BUS(&vser->bus), NULL);
1145 
1146     virtio_cleanup(vdev);
1147 }
1148 
1149 /* Note: 'console' is used for backwards compatibility */
1150 static const VMStateDescription vmstate_virtio_console = {
1151     .name = "virtio-console",
1152     .minimum_version_id = 3,
1153     .version_id = 3,
1154     .fields = (VMStateField[]) {
1155         VMSTATE_VIRTIO_DEVICE,
1156         VMSTATE_END_OF_LIST()
1157     },
1158 };
1159 
1160 static Property virtio_serial_properties[] = {
1161     DEFINE_PROP_UINT32("max_ports", VirtIOSerial, serial.max_virtserial_ports,
1162                                                   31),
1163     DEFINE_PROP_BIT64("emergency-write", VirtIOSerial, host_features,
1164                       VIRTIO_CONSOLE_F_EMERG_WRITE, true),
1165     DEFINE_PROP_END_OF_LIST(),
1166 };
1167 
1168 static void virtio_serial_class_init(ObjectClass *klass, void *data)
1169 {
1170     DeviceClass *dc = DEVICE_CLASS(klass);
1171     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
1172     HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
1173 
1174     QLIST_INIT(&vserdevices.devices);
1175 
1176     device_class_set_props(dc, virtio_serial_properties);
1177     dc->vmsd = &vmstate_virtio_console;
1178     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
1179     vdc->realize = virtio_serial_device_realize;
1180     vdc->unrealize = virtio_serial_device_unrealize;
1181     vdc->get_features = get_features;
1182     vdc->get_config = get_config;
1183     vdc->set_config = set_config;
1184     vdc->set_status = set_status;
1185     vdc->reset = vser_reset;
1186     vdc->save = virtio_serial_save_device;
1187     vdc->load = virtio_serial_load_device;
1188     hc->plug = virtser_port_device_plug;
1189     hc->unplug = qdev_simple_device_unplug_cb;
1190 }
1191 
1192 static const TypeInfo virtio_device_info = {
1193     .name = TYPE_VIRTIO_SERIAL,
1194     .parent = TYPE_VIRTIO_DEVICE,
1195     .instance_size = sizeof(VirtIOSerial),
1196     .class_init = virtio_serial_class_init,
1197     .interfaces = (InterfaceInfo[]) {
1198         { TYPE_HOTPLUG_HANDLER },
1199         { }
1200     }
1201 };
1202 
1203 static void virtio_serial_register_types(void)
1204 {
1205     type_register_static(&virtser_bus_info);
1206     type_register_static(&virtio_serial_port_type_info);
1207     type_register_static(&virtio_device_info);
1208 }
1209 
1210 type_init(virtio_serial_register_types)
1211