xref: /qemu/hw/virtio/virtio-bus.c (revision 814bb12a) 
1 /*
2  * VirtioBus
3  *
4  *  Copyright (C) 2012 : GreenSocs Ltd
5  *      http://www.greensocs.com/ , email: info@greensocs.com
6  *
7  *  Developed by :
8  *  Frederic Konrad   <fred.konrad@greensocs.com>
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation, either version 2 of the License, or
13  * (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18  * GNU General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License along
21  * with this program; if not, see <http://www.gnu.org/licenses/>.
22  *
23  */
24 
25 #include "qemu/osdep.h"
26 #include "hw/hw.h"
27 #include "qemu/error-report.h"
28 #include "hw/qdev.h"
29 #include "hw/virtio/virtio-bus.h"
30 #include "hw/virtio/virtio.h"
31 
32 /* #define DEBUG_VIRTIO_BUS */
33 
34 #ifdef DEBUG_VIRTIO_BUS
35 #define DPRINTF(fmt, ...) \
36 do { printf("virtio_bus: " fmt , ## __VA_ARGS__); } while (0)
37 #else
38 #define DPRINTF(fmt, ...) do { } while (0)
39 #endif
40 
41 /* A VirtIODevice is being plugged */
42 void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp)
43 {
44     DeviceState *qdev = DEVICE(vdev);
45     BusState *qbus = BUS(qdev_get_parent_bus(qdev));
46     VirtioBusState *bus = VIRTIO_BUS(qbus);
47     VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);
48     VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
49 
50     DPRINTF("%s: plug device.\n", qbus->name);
51 
52     if (klass->pre_plugged != NULL) {
53         klass->pre_plugged(qbus->parent, errp);
54     }
55 
56     /* Get the features of the plugged device. */
57     assert(vdc->get_features != NULL);
58     vdev->host_features = vdc->get_features(vdev, vdev->host_features,
59                                             errp);
60 
61     if (klass->device_plugged != NULL) {
62         klass->device_plugged(qbus->parent, errp);
63     }
64 }
65 
66 /* Reset the virtio_bus */
67 void virtio_bus_reset(VirtioBusState *bus)
68 {
69     VirtIODevice *vdev = virtio_bus_get_device(bus);
70 
71     DPRINTF("%s: reset device.\n", BUS(bus)->name);
72     if (vdev != NULL) {
73         virtio_reset(vdev);
74     }
75 }
76 
77 /* A VirtIODevice is being unplugged */
78 void virtio_bus_device_unplugged(VirtIODevice *vdev)
79 {
80     DeviceState *qdev = DEVICE(vdev);
81     BusState *qbus = BUS(qdev_get_parent_bus(qdev));
82     VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(qbus);
83 
84     DPRINTF("%s: remove device.\n", qbus->name);
85 
86     if (vdev != NULL) {
87         if (klass->device_unplugged != NULL) {
88             klass->device_unplugged(qbus->parent);
89         }
90     }
91 }
92 
93 /* Get the device id of the plugged device. */
94 uint16_t virtio_bus_get_vdev_id(VirtioBusState *bus)
95 {
96     VirtIODevice *vdev = virtio_bus_get_device(bus);
97     assert(vdev != NULL);
98     return vdev->device_id;
99 }
100 
101 /* Get the config_len field of the plugged device. */
102 size_t virtio_bus_get_vdev_config_len(VirtioBusState *bus)
103 {
104     VirtIODevice *vdev = virtio_bus_get_device(bus);
105     assert(vdev != NULL);
106     return vdev->config_len;
107 }
108 
109 /* Get bad features of the plugged device. */
110 uint32_t virtio_bus_get_vdev_bad_features(VirtioBusState *bus)
111 {
112     VirtIODevice *vdev = virtio_bus_get_device(bus);
113     VirtioDeviceClass *k;
114 
115     assert(vdev != NULL);
116     k = VIRTIO_DEVICE_GET_CLASS(vdev);
117     if (k->bad_features != NULL) {
118         return k->bad_features(vdev);
119     } else {
120         return 0;
121     }
122 }
123 
124 /* Get config of the plugged device. */
125 void virtio_bus_get_vdev_config(VirtioBusState *bus, uint8_t *config)
126 {
127     VirtIODevice *vdev = virtio_bus_get_device(bus);
128     VirtioDeviceClass *k;
129 
130     assert(vdev != NULL);
131     k = VIRTIO_DEVICE_GET_CLASS(vdev);
132     if (k->get_config != NULL) {
133         k->get_config(vdev, config);
134     }
135 }
136 
137 /* Set config of the plugged device. */
138 void virtio_bus_set_vdev_config(VirtioBusState *bus, uint8_t *config)
139 {
140     VirtIODevice *vdev = virtio_bus_get_device(bus);
141     VirtioDeviceClass *k;
142 
143     assert(vdev != NULL);
144     k = VIRTIO_DEVICE_GET_CLASS(vdev);
145     if (k->set_config != NULL) {
146         k->set_config(vdev, config);
147     }
148 }
149 
150 /*
151  * This function handles both assigning the ioeventfd handler and
152  * registering it with the kernel.
153  * assign: register/deregister ioeventfd with the kernel
154  * set_handler: use the generic ioeventfd handler
155  */
156 static int set_host_notifier_internal(DeviceState *proxy, VirtioBusState *bus,
157                                       int n, bool assign, bool set_handler)
158 {
159     VirtIODevice *vdev = virtio_bus_get_device(bus);
160     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
161     VirtQueue *vq = virtio_get_queue(vdev, n);
162     EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
163     int r = 0;
164 
165     if (assign) {
166         r = event_notifier_init(notifier, 1);
167         if (r < 0) {
168             error_report("%s: unable to init event notifier: %s (%d)",
169                          __func__, strerror(-r), r);
170             return r;
171         }
172         virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
173         r = k->ioeventfd_assign(proxy, notifier, n, assign);
174         if (r < 0) {
175             error_report("%s: unable to assign ioeventfd: %d", __func__, r);
176             virtio_queue_set_host_notifier_fd_handler(vq, false, false);
177             event_notifier_cleanup(notifier);
178             return r;
179         }
180     } else {
181         k->ioeventfd_assign(proxy, notifier, n, assign);
182         virtio_queue_set_host_notifier_fd_handler(vq, false, false);
183         event_notifier_cleanup(notifier);
184     }
185     return r;
186 }
187 
188 void virtio_bus_start_ioeventfd(VirtioBusState *bus)
189 {
190     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
191     DeviceState *proxy = DEVICE(BUS(bus)->parent);
192     VirtIODevice *vdev;
193     int n, r;
194 
195     if (!k->ioeventfd_started || k->ioeventfd_started(proxy)) {
196         return;
197     }
198     if (k->ioeventfd_disabled(proxy)) {
199         return;
200     }
201     vdev = virtio_bus_get_device(bus);
202     for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
203         if (!virtio_queue_get_num(vdev, n)) {
204             continue;
205         }
206         r = set_host_notifier_internal(proxy, bus, n, true, true);
207         if (r < 0) {
208             goto assign_error;
209         }
210     }
211     k->ioeventfd_set_started(proxy, true, false);
212     return;
213 
214 assign_error:
215     while (--n >= 0) {
216         if (!virtio_queue_get_num(vdev, n)) {
217             continue;
218         }
219 
220         r = set_host_notifier_internal(proxy, bus, n, false, false);
221         assert(r >= 0);
222     }
223     k->ioeventfd_set_started(proxy, false, true);
224     error_report("%s: failed. Fallback to userspace (slower).", __func__);
225 }
226 
227 void virtio_bus_stop_ioeventfd(VirtioBusState *bus)
228 {
229     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
230     DeviceState *proxy = DEVICE(BUS(bus)->parent);
231     VirtIODevice *vdev;
232     int n, r;
233 
234     if (!k->ioeventfd_started || !k->ioeventfd_started(proxy)) {
235         return;
236     }
237     vdev = virtio_bus_get_device(bus);
238     for (n = 0; n < VIRTIO_QUEUE_MAX; n++) {
239         if (!virtio_queue_get_num(vdev, n)) {
240             continue;
241         }
242         r = set_host_notifier_internal(proxy, bus, n, false, false);
243         assert(r >= 0);
244     }
245     k->ioeventfd_set_started(proxy, false, false);
246 }
247 
248 /*
249  * This function switches from/to the generic ioeventfd handler.
250  * assign==false means 'use generic ioeventfd handler'.
251  */
252 int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign)
253 {
254     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
255     DeviceState *proxy = DEVICE(BUS(bus)->parent);
256 
257     if (!k->ioeventfd_started) {
258         return -ENOSYS;
259     }
260     k->ioeventfd_set_disabled(proxy, assign);
261     if (assign) {
262         /*
263          * Stop using the generic ioeventfd, we are doing eventfd handling
264          * ourselves below
265          *
266          * FIXME: We should just switch the handler and not deassign the
267          * ioeventfd.
268          * Otherwise, there's a window where we don't have an
269          * ioeventfd and we may end up with a notification where
270          * we don't expect one.
271          */
272         virtio_bus_stop_ioeventfd(bus);
273     }
274     return set_host_notifier_internal(proxy, bus, n, assign, false);
275 }
276 
277 static char *virtio_bus_get_dev_path(DeviceState *dev)
278 {
279     BusState *bus = qdev_get_parent_bus(dev);
280     DeviceState *proxy = DEVICE(bus->parent);
281     return qdev_get_dev_path(proxy);
282 }
283 
284 static char *virtio_bus_get_fw_dev_path(DeviceState *dev)
285 {
286     return NULL;
287 }
288 
289 static void virtio_bus_class_init(ObjectClass *klass, void *data)
290 {
291     BusClass *bus_class = BUS_CLASS(klass);
292     bus_class->get_dev_path = virtio_bus_get_dev_path;
293     bus_class->get_fw_dev_path = virtio_bus_get_fw_dev_path;
294 }
295 
296 static const TypeInfo virtio_bus_info = {
297     .name = TYPE_VIRTIO_BUS,
298     .parent = TYPE_BUS,
299     .instance_size = sizeof(VirtioBusState),
300     .abstract = true,
301     .class_size = sizeof(VirtioBusClass),
302     .class_init = virtio_bus_class_init
303 };
304 
305 static void virtio_register_types(void)
306 {
307     type_register_static(&virtio_bus_info);
308 }
309 
310 type_init(virtio_register_types)
311