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[qemu.git] / hw / char / virtio-console.c
1 /*
2 * Virtio Console and Generic Serial Port Devices
3 *
4 * Copyright Red Hat, Inc. 2009, 2010
5 *
6 * Authors:
7 * Amit Shah <amit.shah@redhat.com>
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2. See
10 * the COPYING file in the top-level directory.
11 */
12
13 #include "qemu/osdep.h"
14 #include "chardev/char-fe.h"
15 #include "qemu/error-report.h"
16 #include "qemu/module.h"
17 #include "trace.h"
18 #include "hw/qdev-properties.h"
19 #include "hw/virtio/virtio-serial.h"
20 #include "qapi/error.h"
21 #include "qapi/qapi-events-char.h"
22
23 #define TYPE_VIRTIO_CONSOLE_SERIAL_PORT "virtserialport"
24 #define VIRTIO_CONSOLE(obj) \
25 OBJECT_CHECK(VirtConsole, (obj), TYPE_VIRTIO_CONSOLE_SERIAL_PORT)
26
27 typedef struct VirtConsole {
28 VirtIOSerialPort parent_obj;
29
30 CharBackend chr;
31 guint watch;
32 } VirtConsole;
33
34 /*
35 * Callback function that's called from chardevs when backend becomes
36 * writable.
37 */
38 static gboolean chr_write_unblocked(GIOChannel *chan, GIOCondition cond,
39 void *opaque)
40 {
41 VirtConsole *vcon = opaque;
42
43 vcon->watch = 0;
44 virtio_serial_throttle_port(VIRTIO_SERIAL_PORT(vcon), false);
45 return FALSE;
46 }
47
48 /* Callback function that's called when the guest sends us data */
49 static ssize_t flush_buf(VirtIOSerialPort *port,
50 const uint8_t *buf, ssize_t len)
51 {
52 VirtConsole *vcon = VIRTIO_CONSOLE(port);
53 ssize_t ret;
54
55 if (!qemu_chr_fe_backend_connected(&vcon->chr)) {
56 /* If there's no backend, we can just say we consumed all data. */
57 return len;
58 }
59
60 ret = qemu_chr_fe_write(&vcon->chr, buf, len);
61 trace_virtio_console_flush_buf(port->id, len, ret);
62
63 if (ret < len) {
64 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
65
66 /*
67 * Ideally we'd get a better error code than just -1, but
68 * that's what the chardev interface gives us right now. If
69 * we had a finer-grained message, like -EPIPE, we could close
70 * this connection.
71 */
72 if (ret < 0)
73 ret = 0;
74
75 /* XXX we should be queuing data to send later for the
76 * console devices too rather than silently dropping
77 * console data on EAGAIN. The Linux virtio-console
78 * hvc driver though does sends with spinlocks held,
79 * so if we enable throttling that'll stall the entire
80 * guest kernel, not merely the process writing to the
81 * console.
82 *
83 * While we could queue data for later write without
84 * enabling throttling, this would result in the guest
85 * being able to trigger arbitrary memory usage in QEMU
86 * buffering data for later writes.
87 *
88 * So fixing this problem likely requires fixing the
89 * Linux virtio-console hvc driver to not hold spinlocks
90 * while writing, and instead merely block the process
91 * that's writing. QEMU would then need some way to detect
92 * if the guest had the fixed driver too, before we can
93 * use throttling on host side.
94 */
95 if (!k->is_console) {
96 virtio_serial_throttle_port(port, true);
97 if (!vcon->watch) {
98 vcon->watch = qemu_chr_fe_add_watch(&vcon->chr,
99 G_IO_OUT|G_IO_HUP,
100 chr_write_unblocked, vcon);
101 }
102 }
103 }
104 return ret;
105 }
106
107 /* Callback function that's called when the guest opens/closes the port */
108 static void set_guest_connected(VirtIOSerialPort *port, int guest_connected)
109 {
110 VirtConsole *vcon = VIRTIO_CONSOLE(port);
111 DeviceState *dev = DEVICE(port);
112 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
113
114 if (!k->is_console) {
115 qemu_chr_fe_set_open(&vcon->chr, guest_connected);
116 }
117
118 if (dev->id) {
119 qapi_event_send_vserport_change(dev->id, guest_connected);
120 }
121 }
122
123 static void guest_writable(VirtIOSerialPort *port)
124 {
125 VirtConsole *vcon = VIRTIO_CONSOLE(port);
126
127 qemu_chr_fe_accept_input(&vcon->chr);
128 }
129
130 /* Readiness of the guest to accept data on a port */
131 static int chr_can_read(void *opaque)
132 {
133 VirtConsole *vcon = opaque;
134
135 return virtio_serial_guest_ready(VIRTIO_SERIAL_PORT(vcon));
136 }
137
138 /* Send data from a char device over to the guest */
139 static void chr_read(void *opaque, const uint8_t *buf, int size)
140 {
141 VirtConsole *vcon = opaque;
142 VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(vcon);
143
144 trace_virtio_console_chr_read(port->id, size);
145 virtio_serial_write(port, buf, size);
146 }
147
148 static void chr_event(void *opaque, QEMUChrEvent event)
149 {
150 VirtConsole *vcon = opaque;
151 VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(vcon);
152
153 trace_virtio_console_chr_event(port->id, event);
154 switch (event) {
155 case CHR_EVENT_OPENED:
156 virtio_serial_open(port);
157 break;
158 case CHR_EVENT_CLOSED:
159 if (vcon->watch) {
160 g_source_remove(vcon->watch);
161 vcon->watch = 0;
162 }
163 virtio_serial_close(port);
164 break;
165 case CHR_EVENT_BREAK:
166 case CHR_EVENT_MUX_IN:
167 case CHR_EVENT_MUX_OUT:
168 /* Ignore */
169 break;
170 }
171 }
172
173 static int chr_be_change(void *opaque)
174 {
175 VirtConsole *vcon = opaque;
176 VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(vcon);
177 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
178
179 if (k->is_console) {
180 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
181 NULL, chr_be_change, vcon, NULL, true);
182 } else {
183 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
184 chr_event, chr_be_change, vcon, NULL, false);
185 }
186
187 if (vcon->watch) {
188 g_source_remove(vcon->watch);
189 vcon->watch = qemu_chr_fe_add_watch(&vcon->chr,
190 G_IO_OUT | G_IO_HUP,
191 chr_write_unblocked, vcon);
192 }
193
194 return 0;
195 }
196
197 static void virtconsole_enable_backend(VirtIOSerialPort *port, bool enable)
198 {
199 VirtConsole *vcon = VIRTIO_CONSOLE(port);
200
201 if (!qemu_chr_fe_backend_connected(&vcon->chr)) {
202 return;
203 }
204
205 if (enable) {
206 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
207
208 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
209 k->is_console ? NULL : chr_event,
210 chr_be_change, vcon, NULL, false);
211 } else {
212 qemu_chr_fe_set_handlers(&vcon->chr, NULL, NULL, NULL,
213 NULL, NULL, NULL, false);
214 }
215 }
216
217 static void virtconsole_realize(DeviceState *dev, Error **errp)
218 {
219 VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
220 VirtConsole *vcon = VIRTIO_CONSOLE(dev);
221 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(dev);
222
223 if (port->id == 0 && !k->is_console) {
224 error_setg(errp, "Port number 0 on virtio-serial devices reserved "
225 "for virtconsole devices for backward compatibility.");
226 return;
227 }
228
229 if (qemu_chr_fe_backend_connected(&vcon->chr)) {
230 /*
231 * For consoles we don't block guest data transfer just
232 * because nothing is connected - we'll just let it go
233 * whetherever the chardev wants - /dev/null probably.
234 *
235 * For serial ports we need 100% reliable data transfer
236 * so we use the opened/closed signals from chardev to
237 * trigger open/close of the device
238 */
239 if (k->is_console) {
240 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
241 NULL, chr_be_change,
242 vcon, NULL, true);
243 virtio_serial_open(port);
244 } else {
245 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
246 chr_event, chr_be_change,
247 vcon, NULL, false);
248 }
249 }
250 }
251
252 static void virtconsole_unrealize(DeviceState *dev)
253 {
254 VirtConsole *vcon = VIRTIO_CONSOLE(dev);
255
256 if (vcon->watch) {
257 g_source_remove(vcon->watch);
258 }
259 }
260
261 static void virtconsole_class_init(ObjectClass *klass, void *data)
262 {
263 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_CLASS(klass);
264
265 k->is_console = true;
266 }
267
268 static const TypeInfo virtconsole_info = {
269 .name = "virtconsole",
270 .parent = TYPE_VIRTIO_CONSOLE_SERIAL_PORT,
271 .class_init = virtconsole_class_init,
272 };
273
274 static Property virtserialport_properties[] = {
275 DEFINE_PROP_CHR("chardev", VirtConsole, chr),
276 DEFINE_PROP_END_OF_LIST(),
277 };
278
279 static void virtserialport_class_init(ObjectClass *klass, void *data)
280 {
281 DeviceClass *dc = DEVICE_CLASS(klass);
282 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_CLASS(klass);
283
284 k->realize = virtconsole_realize;
285 k->unrealize = virtconsole_unrealize;
286 k->have_data = flush_buf;
287 k->set_guest_connected = set_guest_connected;
288 k->enable_backend = virtconsole_enable_backend;
289 k->guest_writable = guest_writable;
290 device_class_set_props(dc, virtserialport_properties);
291 }
292
293 static const TypeInfo virtserialport_info = {
294 .name = TYPE_VIRTIO_CONSOLE_SERIAL_PORT,
295 .parent = TYPE_VIRTIO_SERIAL_PORT,
296 .instance_size = sizeof(VirtConsole),
297 .class_init = virtserialport_class_init,
298 };
299
300 static void virtconsole_register_types(void)
301 {
302 type_register_static(&virtserialport_info);
303 type_register_static(&virtconsole_info);
304 }
305
306 type_init(virtconsole_register_types)