xref: /qemu/hw/virtio/vhost-user-gpio.c (revision 3d558330) 
1 /*
2  * Vhost-user GPIO virtio device
3  *
4  * Copyright (c) 2022 Viresh Kumar <viresh.kumar@linaro.org>
5  *
6  * SPDX-License-Identifier: GPL-2.0-or-later
7  */
8 
9 #include "qemu/osdep.h"
10 #include "qapi/error.h"
11 #include "hw/qdev-properties.h"
12 #include "hw/virtio/virtio-bus.h"
13 #include "hw/virtio/vhost-user-gpio.h"
14 #include "qemu/error-report.h"
15 #include "standard-headers/linux/virtio_ids.h"
16 #include "trace.h"
17 
18 #define REALIZE_CONNECTION_RETRIES 3
19 
20 /* Features required from VirtIO */
21 static const int feature_bits[] = {
22     VIRTIO_F_VERSION_1,
23     VIRTIO_F_NOTIFY_ON_EMPTY,
24     VIRTIO_RING_F_INDIRECT_DESC,
25     VIRTIO_RING_F_EVENT_IDX,
26     VIRTIO_GPIO_F_IRQ,
27     VIRTIO_F_RING_RESET,
28     VHOST_INVALID_FEATURE_BIT
29 };
30 
31 static void vu_gpio_get_config(VirtIODevice *vdev, uint8_t *config)
32 {
33     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
34 
35     memcpy(config, &gpio->config, sizeof(gpio->config));
36 }
37 
38 static int vu_gpio_config_notifier(struct vhost_dev *dev)
39 {
40     VHostUserGPIO *gpio = VHOST_USER_GPIO(dev->vdev);
41 
42     memcpy(dev->vdev->config, &gpio->config, sizeof(gpio->config));
43     virtio_notify_config(dev->vdev);
44 
45     return 0;
46 }
47 
48 const VhostDevConfigOps gpio_ops = {
49     .vhost_dev_config_notifier = vu_gpio_config_notifier,
50 };
51 
52 static int vu_gpio_start(VirtIODevice *vdev)
53 {
54     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
55     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
56     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
57     struct vhost_dev *vhost_dev = &gpio->vhost_dev;
58     int ret, i;
59 
60     if (!k->set_guest_notifiers) {
61         error_report("binding does not support guest notifiers");
62         return -ENOSYS;
63     }
64 
65     ret = vhost_dev_enable_notifiers(vhost_dev, vdev);
66     if (ret < 0) {
67         error_report("Error enabling host notifiers: %d", ret);
68         return ret;
69     }
70 
71     ret = k->set_guest_notifiers(qbus->parent, vhost_dev->nvqs, true);
72     if (ret < 0) {
73         error_report("Error binding guest notifier: %d", ret);
74         goto err_host_notifiers;
75     }
76 
77     /*
78      * Before we start up we need to ensure we have the final feature
79      * set needed for the vhost configuration. The backend may also
80      * apply backend_features when the feature set is sent.
81      */
82     vhost_ack_features(&gpio->vhost_dev, feature_bits, vdev->guest_features);
83 
84     ret = vhost_dev_start(&gpio->vhost_dev, vdev, false);
85     if (ret < 0) {
86         error_report("Error starting vhost-user-gpio: %d", ret);
87         goto err_guest_notifiers;
88     }
89     gpio->started_vu = true;
90 
91     /*
92      * guest_notifier_mask/pending not used yet, so just unmask
93      * everything here. virtio-pci will do the right thing by
94      * enabling/disabling irqfd.
95      */
96     for (i = 0; i < gpio->vhost_dev.nvqs; i++) {
97         vhost_virtqueue_mask(&gpio->vhost_dev, vdev, i, false);
98     }
99 
100     /*
101      * As we must have VHOST_USER_F_PROTOCOL_FEATURES (because
102      * VHOST_USER_GET_CONFIG requires it) we need to explicitly enable
103      * the vrings.
104      */
105     g_assert(vhost_dev->vhost_ops &&
106              vhost_dev->vhost_ops->vhost_set_vring_enable);
107     ret = vhost_dev->vhost_ops->vhost_set_vring_enable(vhost_dev, true);
108     if (ret == 0) {
109         return 0;
110     }
111 
112     error_report("Failed to start vrings for vhost-user-gpio: %d", ret);
113 
114 err_guest_notifiers:
115     k->set_guest_notifiers(qbus->parent, gpio->vhost_dev.nvqs, false);
116 err_host_notifiers:
117     vhost_dev_disable_notifiers(&gpio->vhost_dev, vdev);
118 
119     return ret;
120 }
121 
122 static void vu_gpio_stop(VirtIODevice *vdev)
123 {
124     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
125     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
126     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
127     struct vhost_dev *vhost_dev = &gpio->vhost_dev;
128     int ret;
129 
130     if (!gpio->started_vu) {
131         return;
132     }
133     gpio->started_vu = false;
134 
135     if (!k->set_guest_notifiers) {
136         return;
137     }
138 
139     vhost_dev_stop(vhost_dev, vdev, false);
140 
141     ret = k->set_guest_notifiers(qbus->parent, vhost_dev->nvqs, false);
142     if (ret < 0) {
143         error_report("vhost guest notifier cleanup failed: %d", ret);
144         return;
145     }
146 
147     vhost_dev_disable_notifiers(vhost_dev, vdev);
148 }
149 
150 static void vu_gpio_set_status(VirtIODevice *vdev, uint8_t status)
151 {
152     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
153     bool should_start = virtio_device_should_start(vdev, status);
154 
155     trace_virtio_gpio_set_status(status);
156 
157     if (!gpio->connected) {
158         return;
159     }
160 
161     if (vhost_dev_is_started(&gpio->vhost_dev) == should_start) {
162         return;
163     }
164 
165     if (should_start) {
166         if (vu_gpio_start(vdev)) {
167             qemu_chr_fe_disconnect(&gpio->chardev);
168         }
169     } else {
170         vu_gpio_stop(vdev);
171     }
172 }
173 
174 static uint64_t vu_gpio_get_features(VirtIODevice *vdev, uint64_t features,
175                                      Error **errp)
176 {
177     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
178 
179     return vhost_get_features(&gpio->vhost_dev, feature_bits, features);
180 }
181 
182 static void vu_gpio_handle_output(VirtIODevice *vdev, VirtQueue *vq)
183 {
184     /*
185      * Not normally called; it's the daemon that handles the queue;
186      * however virtio's cleanup path can call this.
187      */
188 }
189 
190 static void vu_gpio_guest_notifier_mask(VirtIODevice *vdev, int idx, bool mask)
191 {
192     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
193 
194     vhost_virtqueue_mask(&gpio->vhost_dev, vdev, idx, mask);
195 }
196 
197 static void do_vhost_user_cleanup(VirtIODevice *vdev, VHostUserGPIO *gpio)
198 {
199     virtio_delete_queue(gpio->command_vq);
200     virtio_delete_queue(gpio->interrupt_vq);
201     g_free(gpio->vhost_dev.vqs);
202     gpio->vhost_dev.vqs = NULL;
203     virtio_cleanup(vdev);
204     vhost_user_cleanup(&gpio->vhost_user);
205 }
206 
207 static int vu_gpio_connect(DeviceState *dev, Error **errp)
208 {
209     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
210     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
211     struct vhost_dev *vhost_dev = &gpio->vhost_dev;
212     int ret;
213 
214     if (gpio->connected) {
215         return 0;
216     }
217     gpio->connected = true;
218 
219     vhost_dev_set_config_notifier(vhost_dev, &gpio_ops);
220     gpio->vhost_user.supports_config = true;
221 
222     ret = vhost_dev_init(vhost_dev, &gpio->vhost_user,
223                          VHOST_BACKEND_TYPE_USER, 0, errp);
224     if (ret < 0) {
225         return ret;
226     }
227 
228     /* restore vhost state */
229     if (virtio_device_started(vdev, vdev->status)) {
230         vu_gpio_start(vdev);
231     }
232 
233     return 0;
234 }
235 
236 static void vu_gpio_event(void *opaque, QEMUChrEvent event);
237 
238 static void vu_gpio_disconnect(DeviceState *dev)
239 {
240     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
241     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
242 
243     if (!gpio->connected) {
244         return;
245     }
246     gpio->connected = false;
247 
248     vu_gpio_stop(vdev);
249     vhost_dev_cleanup(&gpio->vhost_dev);
250 
251     /* Re-instate the event handler for new connections */
252     qemu_chr_fe_set_handlers(&gpio->chardev,
253                              NULL, NULL, vu_gpio_event,
254                              NULL, dev, NULL, true);
255 }
256 
257 static void vu_gpio_event(void *opaque, QEMUChrEvent event)
258 {
259     DeviceState *dev = opaque;
260     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
261     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
262     Error *local_err = NULL;
263 
264     switch (event) {
265     case CHR_EVENT_OPENED:
266         if (vu_gpio_connect(dev, &local_err) < 0) {
267             qemu_chr_fe_disconnect(&gpio->chardev);
268             return;
269         }
270         break;
271     case CHR_EVENT_CLOSED:
272         /* defer close until later to avoid circular close */
273         vhost_user_async_close(dev, &gpio->chardev, &gpio->vhost_dev,
274                                vu_gpio_disconnect);
275         break;
276     case CHR_EVENT_BREAK:
277     case CHR_EVENT_MUX_IN:
278     case CHR_EVENT_MUX_OUT:
279         /* Ignore */
280         break;
281     }
282 }
283 
284 static int vu_gpio_realize_connect(VHostUserGPIO *gpio, Error **errp)
285 {
286     VirtIODevice *vdev = &gpio->parent_obj;
287     DeviceState *dev = &vdev->parent_obj;
288     struct vhost_dev *vhost_dev = &gpio->vhost_dev;
289     int ret;
290 
291     ret = qemu_chr_fe_wait_connected(&gpio->chardev, errp);
292     if (ret < 0) {
293         return ret;
294     }
295 
296     /*
297      * vu_gpio_connect() may have already connected (via the event
298      * callback) in which case it will just report success.
299      */
300     ret = vu_gpio_connect(dev, errp);
301     if (ret < 0) {
302         qemu_chr_fe_disconnect(&gpio->chardev);
303         return ret;
304     }
305     g_assert(gpio->connected);
306 
307     ret = vhost_dev_get_config(vhost_dev, (uint8_t *)&gpio->config,
308                                sizeof(gpio->config), errp);
309 
310     if (ret < 0) {
311         error_report("vhost-user-gpio: get config failed");
312 
313         qemu_chr_fe_disconnect(&gpio->chardev);
314         vhost_dev_cleanup(vhost_dev);
315         return ret;
316     }
317 
318     return 0;
319 }
320 
321 static void vu_gpio_device_realize(DeviceState *dev, Error **errp)
322 {
323     ERRP_GUARD();
324 
325     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
326     VHostUserGPIO *gpio = VHOST_USER_GPIO(dev);
327     int retries, ret;
328 
329     if (!gpio->chardev.chr) {
330         error_setg(errp, "vhost-user-gpio: chardev is mandatory");
331         return;
332     }
333 
334     if (!vhost_user_init(&gpio->vhost_user, &gpio->chardev, errp)) {
335         return;
336     }
337 
338     virtio_init(vdev, VIRTIO_ID_GPIO, sizeof(gpio->config));
339 
340     gpio->vhost_dev.nvqs = 2;
341     gpio->command_vq = virtio_add_queue(vdev, 256, vu_gpio_handle_output);
342     gpio->interrupt_vq = virtio_add_queue(vdev, 256, vu_gpio_handle_output);
343     gpio->vhost_dev.vqs = g_new0(struct vhost_virtqueue, gpio->vhost_dev.nvqs);
344 
345     gpio->connected = false;
346 
347     qemu_chr_fe_set_handlers(&gpio->chardev, NULL, NULL, vu_gpio_event, NULL,
348                              dev, NULL, true);
349 
350     retries = REALIZE_CONNECTION_RETRIES;
351     g_assert(!*errp);
352     do {
353         if (*errp) {
354             error_prepend(errp, "Reconnecting after error: ");
355             error_report_err(*errp);
356             *errp = NULL;
357         }
358         ret = vu_gpio_realize_connect(gpio, errp);
359     } while (ret < 0 && retries--);
360 
361     if (ret < 0) {
362         do_vhost_user_cleanup(vdev, gpio);
363     }
364 
365     return;
366 }
367 
368 static void vu_gpio_device_unrealize(DeviceState *dev)
369 {
370     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
371     VHostUserGPIO *gpio = VHOST_USER_GPIO(dev);
372 
373     vu_gpio_set_status(vdev, 0);
374     qemu_chr_fe_set_handlers(&gpio->chardev, NULL, NULL, NULL, NULL, NULL, NULL,
375                              false);
376     vhost_dev_cleanup(&gpio->vhost_dev);
377     do_vhost_user_cleanup(vdev, gpio);
378 }
379 
380 static const VMStateDescription vu_gpio_vmstate = {
381     .name = "vhost-user-gpio",
382     .unmigratable = 1,
383 };
384 
385 static Property vu_gpio_properties[] = {
386     DEFINE_PROP_CHR("chardev", VHostUserGPIO, chardev),
387     DEFINE_PROP_END_OF_LIST(),
388 };
389 
390 static void vu_gpio_class_init(ObjectClass *klass, void *data)
391 {
392     DeviceClass *dc = DEVICE_CLASS(klass);
393     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
394 
395     device_class_set_props(dc, vu_gpio_properties);
396     dc->vmsd = &vu_gpio_vmstate;
397     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
398     vdc->realize = vu_gpio_device_realize;
399     vdc->unrealize = vu_gpio_device_unrealize;
400     vdc->get_features = vu_gpio_get_features;
401     vdc->get_config = vu_gpio_get_config;
402     vdc->set_status = vu_gpio_set_status;
403     vdc->guest_notifier_mask = vu_gpio_guest_notifier_mask;
404 }
405 
406 static const TypeInfo vu_gpio_info = {
407     .name = TYPE_VHOST_USER_GPIO,
408     .parent = TYPE_VIRTIO_DEVICE,
409     .instance_size = sizeof(VHostUserGPIO),
410     .class_init = vu_gpio_class_init,
411 };
412 
413 static void vu_gpio_register_types(void)
414 {
415     type_register_static(&vu_gpio_info);
416 }
417 
418 type_init(vu_gpio_register_types)
419