Merge remote-tracking branch 'remotes/jsnow-gitlab/tags/python-pull-request' into...
[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/qdev-properties-system.h"
20 #include "hw/virtio/virtio-serial.h"
21 #include "qapi/error.h"
22 #include "qapi/qapi-events-char.h"
23 #include "qom/object.h"
24
25 #define TYPE_VIRTIO_CONSOLE_SERIAL_PORT "virtserialport"
26 typedef struct VirtConsole VirtConsole;
27 DECLARE_INSTANCE_CHECKER(VirtConsole, VIRTIO_CONSOLE,
28 TYPE_VIRTIO_CONSOLE_SERIAL_PORT)
29
30 struct VirtConsole {
31 VirtIOSerialPort parent_obj;
32
33 CharBackend chr;
34 guint watch;
35 };
36
37 /*
38 * Callback function that's called from chardevs when backend becomes
39 * writable.
40 */
41 static gboolean chr_write_unblocked(void *do_not_use, GIOCondition cond,
42 void *opaque)
43 {
44 VirtConsole *vcon = opaque;
45
46 vcon->watch = 0;
47 virtio_serial_throttle_port(VIRTIO_SERIAL_PORT(vcon), false);
48 return FALSE;
49 }
50
51 /* Callback function that's called when the guest sends us data */
52 static ssize_t flush_buf(VirtIOSerialPort *port,
53 const uint8_t *buf, ssize_t len)
54 {
55 VirtConsole *vcon = VIRTIO_CONSOLE(port);
56 ssize_t ret;
57
58 if (!qemu_chr_fe_backend_connected(&vcon->chr)) {
59 /* If there's no backend, we can just say we consumed all data. */
60 return len;
61 }
62
63 ret = qemu_chr_fe_write(&vcon->chr, buf, len);
64 trace_virtio_console_flush_buf(port->id, len, ret);
65
66 if (ret < len) {
67 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
68
69 /*
70 * Ideally we'd get a better error code than just -1, but
71 * that's what the chardev interface gives us right now. If
72 * we had a finer-grained message, like -EPIPE, we could close
73 * this connection.
74 */
75 if (ret < 0)
76 ret = 0;
77
78 /* XXX we should be queuing data to send later for the
79 * console devices too rather than silently dropping
80 * console data on EAGAIN. The Linux virtio-console
81 * hvc driver though does sends with spinlocks held,
82 * so if we enable throttling that'll stall the entire
83 * guest kernel, not merely the process writing to the
84 * console.
85 *
86 * While we could queue data for later write without
87 * enabling throttling, this would result in the guest
88 * being able to trigger arbitrary memory usage in QEMU
89 * buffering data for later writes.
90 *
91 * So fixing this problem likely requires fixing the
92 * Linux virtio-console hvc driver to not hold spinlocks
93 * while writing, and instead merely block the process
94 * that's writing. QEMU would then need some way to detect
95 * if the guest had the fixed driver too, before we can
96 * use throttling on host side.
97 */
98 if (!k->is_console) {
99 virtio_serial_throttle_port(port, true);
100 if (!vcon->watch) {
101 vcon->watch = qemu_chr_fe_add_watch(&vcon->chr,
102 G_IO_OUT|G_IO_HUP,
103 chr_write_unblocked, vcon);
104 }
105 }
106 }
107 return ret;
108 }
109
110 /* Callback function that's called when the guest opens/closes the port */
111 static void set_guest_connected(VirtIOSerialPort *port, int guest_connected)
112 {
113 VirtConsole *vcon = VIRTIO_CONSOLE(port);
114 DeviceState *dev = DEVICE(port);
115 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
116
117 if (!k->is_console) {
118 qemu_chr_fe_set_open(&vcon->chr, guest_connected);
119 }
120
121 if (dev->id) {
122 qapi_event_send_vserport_change(dev->id, guest_connected);
123 }
124 }
125
126 static void guest_writable(VirtIOSerialPort *port)
127 {
128 VirtConsole *vcon = VIRTIO_CONSOLE(port);
129
130 qemu_chr_fe_accept_input(&vcon->chr);
131 }
132
133 /* Readiness of the guest to accept data on a port */
134 static int chr_can_read(void *opaque)
135 {
136 VirtConsole *vcon = opaque;
137
138 return virtio_serial_guest_ready(VIRTIO_SERIAL_PORT(vcon));
139 }
140
141 /* Send data from a char device over to the guest */
142 static void chr_read(void *opaque, const uint8_t *buf, int size)
143 {
144 VirtConsole *vcon = opaque;
145 VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(vcon);
146
147 trace_virtio_console_chr_read(port->id, size);
148 virtio_serial_write(port, buf, size);
149 }
150
151 static void chr_event(void *opaque, QEMUChrEvent event)
152 {
153 VirtConsole *vcon = opaque;
154 VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(vcon);
155
156 trace_virtio_console_chr_event(port->id, event);
157 switch (event) {
158 case CHR_EVENT_OPENED:
159 virtio_serial_open(port);
160 break;
161 case CHR_EVENT_CLOSED:
162 if (vcon->watch) {
163 g_source_remove(vcon->watch);
164 vcon->watch = 0;
165 }
166 virtio_serial_close(port);
167 break;
168 case CHR_EVENT_BREAK:
169 case CHR_EVENT_MUX_IN:
170 case CHR_EVENT_MUX_OUT:
171 /* Ignore */
172 break;
173 }
174 }
175
176 static int chr_be_change(void *opaque)
177 {
178 VirtConsole *vcon = opaque;
179 VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(vcon);
180 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
181
182 if (k->is_console) {
183 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
184 NULL, chr_be_change, vcon, NULL, true);
185 } else {
186 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
187 chr_event, chr_be_change, vcon, NULL, false);
188 }
189
190 if (vcon->watch) {
191 g_source_remove(vcon->watch);
192 vcon->watch = qemu_chr_fe_add_watch(&vcon->chr,
193 G_IO_OUT | G_IO_HUP,
194 chr_write_unblocked, vcon);
195 }
196
197 return 0;
198 }
199
200 static void virtconsole_enable_backend(VirtIOSerialPort *port, bool enable)
201 {
202 VirtConsole *vcon = VIRTIO_CONSOLE(port);
203
204 if (!qemu_chr_fe_backend_connected(&vcon->chr)) {
205 return;
206 }
207
208 if (enable) {
209 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
210
211 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
212 k->is_console ? NULL : chr_event,
213 chr_be_change, vcon, NULL, false);
214 } else {
215 qemu_chr_fe_set_handlers(&vcon->chr, NULL, NULL, NULL,
216 NULL, NULL, NULL, false);
217 }
218 }
219
220 static void virtconsole_realize(DeviceState *dev, Error **errp)
221 {
222 VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
223 VirtConsole *vcon = VIRTIO_CONSOLE(dev);
224 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(dev);
225
226 if (port->id == 0 && !k->is_console) {
227 error_setg(errp, "Port number 0 on virtio-serial devices reserved "
228 "for virtconsole devices for backward compatibility.");
229 return;
230 }
231
232 if (qemu_chr_fe_backend_connected(&vcon->chr)) {
233 /*
234 * For consoles we don't block guest data transfer just
235 * because nothing is connected - we'll just let it go
236 * whetherever the chardev wants - /dev/null probably.
237 *
238 * For serial ports we need 100% reliable data transfer
239 * so we use the opened/closed signals from chardev to
240 * trigger open/close of the device
241 */
242 if (k->is_console) {
243 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
244 NULL, chr_be_change,
245 vcon, NULL, true);
246 virtio_serial_open(port);
247 } else {
248 qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
249 chr_event, chr_be_change,
250 vcon, NULL, false);
251 }
252 }
253 }
254
255 static void virtconsole_unrealize(DeviceState *dev)
256 {
257 VirtConsole *vcon = VIRTIO_CONSOLE(dev);
258
259 if (vcon->watch) {
260 g_source_remove(vcon->watch);
261 }
262 }
263
264 static void virtconsole_class_init(ObjectClass *klass, void *data)
265 {
266 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_CLASS(klass);
267
268 k->is_console = true;
269 }
270
271 static const TypeInfo virtconsole_info = {
272 .name = "virtconsole",
273 .parent = TYPE_VIRTIO_CONSOLE_SERIAL_PORT,
274 .class_init = virtconsole_class_init,
275 };
276
277 static Property virtserialport_properties[] = {
278 DEFINE_PROP_CHR("chardev", VirtConsole, chr),
279 DEFINE_PROP_END_OF_LIST(),
280 };
281
282 static void virtserialport_class_init(ObjectClass *klass, void *data)
283 {
284 DeviceClass *dc = DEVICE_CLASS(klass);
285 VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_CLASS(klass);
286
287 k->realize = virtconsole_realize;
288 k->unrealize = virtconsole_unrealize;
289 k->have_data = flush_buf;
290 k->set_guest_connected = set_guest_connected;
291 k->enable_backend = virtconsole_enable_backend;
292 k->guest_writable = guest_writable;
293 device_class_set_props(dc, virtserialport_properties);
294 }
295
296 static const TypeInfo virtserialport_info = {
297 .name = TYPE_VIRTIO_CONSOLE_SERIAL_PORT,
298 .parent = TYPE_VIRTIO_SERIAL_PORT,
299 .instance_size = sizeof(VirtConsole),
300 .class_init = virtserialport_class_init,
301 };
302
303 static void virtconsole_register_types(void)
304 {
305 type_register_static(&virtserialport_info);
306 type_register_static(&virtconsole_info);
307 }
308
309 type_init(virtconsole_register_types)