xref: /openbmc/qemu/hw/virtio/vhost-user-gpio.c (revision c23a9563) 
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);
85     if (ret < 0) {
86         error_report("Error starting vhost-user-gpio: %d", ret);
87         goto err_guest_notifiers;
88     }
89 
90     /*
91      * guest_notifier_mask/pending not used yet, so just unmask
92      * everything here. virtio-pci will do the right thing by
93      * enabling/disabling irqfd.
94      */
95     for (i = 0; i < gpio->vhost_dev.nvqs; i++) {
96         vhost_virtqueue_mask(&gpio->vhost_dev, vdev, i, false);
97     }
98 
99     /*
100      * As we must have VHOST_USER_F_PROTOCOL_FEATURES (because
101      * VHOST_USER_GET_CONFIG requires it) we need to explicitly enable
102      * the vrings.
103      */
104     g_assert(vhost_dev->vhost_ops &&
105              vhost_dev->vhost_ops->vhost_set_vring_enable);
106     ret = vhost_dev->vhost_ops->vhost_set_vring_enable(vhost_dev, true);
107     if (ret == 0) {
108         return 0;
109     }
110 
111     error_report("Failed to start vrings for vhost-user-gpio: %d", ret);
112 
113 err_guest_notifiers:
114     k->set_guest_notifiers(qbus->parent, gpio->vhost_dev.nvqs, false);
115 err_host_notifiers:
116     vhost_dev_disable_notifiers(&gpio->vhost_dev, vdev);
117 
118     return ret;
119 }
120 
121 static void vu_gpio_stop(VirtIODevice *vdev)
122 {
123     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
124     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
125     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
126     struct vhost_dev *vhost_dev = &gpio->vhost_dev;
127     int ret;
128 
129     if (!k->set_guest_notifiers) {
130         return;
131     }
132 
133     /*
134      * We can call vu_gpio_stop multiple times, for example from
135      * vm_state_notify and the final object finalisation. Check we
136      * aren't already stopped before doing so.
137      */
138     if (!vhost_dev_is_started(vhost_dev)) {
139         return;
140     }
141 
142     vhost_dev_stop(vhost_dev, vdev);
143 
144     ret = k->set_guest_notifiers(qbus->parent, vhost_dev->nvqs, false);
145     if (ret < 0) {
146         error_report("vhost guest notifier cleanup failed: %d", ret);
147         return;
148     }
149 
150     vhost_dev_disable_notifiers(vhost_dev, vdev);
151 }
152 
153 static void vu_gpio_set_status(VirtIODevice *vdev, uint8_t status)
154 {
155     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
156     bool should_start = virtio_device_should_start(vdev, status);
157 
158     trace_virtio_gpio_set_status(status);
159 
160     if (!gpio->connected) {
161         return;
162     }
163 
164     if (vhost_dev_is_started(&gpio->vhost_dev) == should_start) {
165         return;
166     }
167 
168     if (should_start) {
169         if (vu_gpio_start(vdev)) {
170             qemu_chr_fe_disconnect(&gpio->chardev);
171         }
172     } else {
173         vu_gpio_stop(vdev);
174     }
175 }
176 
177 static uint64_t vu_gpio_get_features(VirtIODevice *vdev, uint64_t features,
178                                      Error **errp)
179 {
180     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
181 
182     return vhost_get_features(&gpio->vhost_dev, feature_bits, features);
183 }
184 
185 static void vu_gpio_handle_output(VirtIODevice *vdev, VirtQueue *vq)
186 {
187     /*
188      * Not normally called; it's the daemon that handles the queue;
189      * however virtio's cleanup path can call this.
190      */
191 }
192 
193 static void vu_gpio_guest_notifier_mask(VirtIODevice *vdev, int idx, bool mask)
194 {
195     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
196 
197     vhost_virtqueue_mask(&gpio->vhost_dev, vdev, idx, mask);
198 }
199 
200 static void do_vhost_user_cleanup(VirtIODevice *vdev, VHostUserGPIO *gpio)
201 {
202     virtio_delete_queue(gpio->command_vq);
203     virtio_delete_queue(gpio->interrupt_vq);
204     g_free(gpio->vhost_dev.vqs);
205     gpio->vhost_dev.vqs = NULL;
206     virtio_cleanup(vdev);
207     vhost_user_cleanup(&gpio->vhost_user);
208 }
209 
210 static int vu_gpio_connect(DeviceState *dev, Error **errp)
211 {
212     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
213     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
214     struct vhost_dev *vhost_dev = &gpio->vhost_dev;
215     int ret;
216 
217     if (gpio->connected) {
218         return 0;
219     }
220     gpio->connected = true;
221 
222     vhost_dev_set_config_notifier(vhost_dev, &gpio_ops);
223     gpio->vhost_user.supports_config = true;
224 
225     ret = vhost_dev_init(vhost_dev, &gpio->vhost_user,
226                          VHOST_BACKEND_TYPE_USER, 0, errp);
227     if (ret < 0) {
228         return ret;
229     }
230 
231     /* restore vhost state */
232     if (virtio_device_started(vdev, vdev->status)) {
233         vu_gpio_start(vdev);
234     }
235 
236     return 0;
237 }
238 
239 static void vu_gpio_disconnect(DeviceState *dev)
240 {
241     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
242     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
243 
244     if (!gpio->connected) {
245         return;
246     }
247     gpio->connected = false;
248 
249     vu_gpio_stop(vdev);
250     vhost_dev_cleanup(&gpio->vhost_dev);
251 }
252 
253 static void vu_gpio_event(void *opaque, QEMUChrEvent event)
254 {
255     DeviceState *dev = opaque;
256     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
257     VHostUserGPIO *gpio = VHOST_USER_GPIO(vdev);
258     Error *local_err = NULL;
259 
260     switch (event) {
261     case CHR_EVENT_OPENED:
262         if (vu_gpio_connect(dev, &local_err) < 0) {
263             qemu_chr_fe_disconnect(&gpio->chardev);
264             return;
265         }
266         break;
267     case CHR_EVENT_CLOSED:
268         vu_gpio_disconnect(dev);
269         break;
270     case CHR_EVENT_BREAK:
271     case CHR_EVENT_MUX_IN:
272     case CHR_EVENT_MUX_OUT:
273         /* Ignore */
274         break;
275     }
276 }
277 
278 static int vu_gpio_realize_connect(VHostUserGPIO *gpio, Error **errp)
279 {
280     VirtIODevice *vdev = &gpio->parent_obj;
281     DeviceState *dev = &vdev->parent_obj;
282     struct vhost_dev *vhost_dev = &gpio->vhost_dev;
283     int ret;
284 
285     ret = qemu_chr_fe_wait_connected(&gpio->chardev, errp);
286     if (ret < 0) {
287         return ret;
288     }
289 
290     /*
291      * vu_gpio_connect() may have already connected (via the event
292      * callback) in which case it will just report success.
293      */
294     ret = vu_gpio_connect(dev, errp);
295     if (ret < 0) {
296         qemu_chr_fe_disconnect(&gpio->chardev);
297         return ret;
298     }
299     g_assert(gpio->connected);
300 
301     ret = vhost_dev_get_config(vhost_dev, (uint8_t *)&gpio->config,
302                                sizeof(gpio->config), errp);
303 
304     if (ret < 0) {
305         error_report("vhost-user-gpio: get config failed");
306 
307         qemu_chr_fe_disconnect(&gpio->chardev);
308         vhost_dev_cleanup(vhost_dev);
309         return ret;
310     }
311 
312     return 0;
313 }
314 
315 static void vu_gpio_device_realize(DeviceState *dev, Error **errp)
316 {
317     ERRP_GUARD();
318 
319     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
320     VHostUserGPIO *gpio = VHOST_USER_GPIO(dev);
321     int retries, ret;
322 
323     if (!gpio->chardev.chr) {
324         error_setg(errp, "vhost-user-gpio: chardev is mandatory");
325         return;
326     }
327 
328     if (!vhost_user_init(&gpio->vhost_user, &gpio->chardev, errp)) {
329         return;
330     }
331 
332     virtio_init(vdev, VIRTIO_ID_GPIO, sizeof(gpio->config));
333 
334     gpio->vhost_dev.nvqs = 2;
335     gpio->command_vq = virtio_add_queue(vdev, 256, vu_gpio_handle_output);
336     gpio->interrupt_vq = virtio_add_queue(vdev, 256, vu_gpio_handle_output);
337     gpio->vhost_dev.vqs = g_new0(struct vhost_virtqueue, gpio->vhost_dev.nvqs);
338 
339     gpio->connected = false;
340 
341     qemu_chr_fe_set_handlers(&gpio->chardev, NULL, NULL, vu_gpio_event, NULL,
342                              dev, NULL, true);
343 
344     retries = REALIZE_CONNECTION_RETRIES;
345     g_assert(!*errp);
346     do {
347         if (*errp) {
348             error_prepend(errp, "Reconnecting after error: ");
349             error_report_err(*errp);
350             *errp = NULL;
351         }
352         ret = vu_gpio_realize_connect(gpio, errp);
353     } while (ret < 0 && retries--);
354 
355     if (ret < 0) {
356         do_vhost_user_cleanup(vdev, gpio);
357     }
358 
359     return;
360 }
361 
362 static void vu_gpio_device_unrealize(DeviceState *dev)
363 {
364     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
365     VHostUserGPIO *gpio = VHOST_USER_GPIO(dev);
366 
367     vu_gpio_set_status(vdev, 0);
368     qemu_chr_fe_set_handlers(&gpio->chardev, NULL, NULL, NULL, NULL, NULL, NULL,
369                              false);
370     vhost_dev_cleanup(&gpio->vhost_dev);
371     do_vhost_user_cleanup(vdev, gpio);
372 }
373 
374 static const VMStateDescription vu_gpio_vmstate = {
375     .name = "vhost-user-gpio",
376     .unmigratable = 1,
377 };
378 
379 static Property vu_gpio_properties[] = {
380     DEFINE_PROP_CHR("chardev", VHostUserGPIO, chardev),
381     DEFINE_PROP_END_OF_LIST(),
382 };
383 
384 static void vu_gpio_class_init(ObjectClass *klass, void *data)
385 {
386     DeviceClass *dc = DEVICE_CLASS(klass);
387     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
388 
389     device_class_set_props(dc, vu_gpio_properties);
390     dc->vmsd = &vu_gpio_vmstate;
391     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
392     vdc->realize = vu_gpio_device_realize;
393     vdc->unrealize = vu_gpio_device_unrealize;
394     vdc->get_features = vu_gpio_get_features;
395     vdc->get_config = vu_gpio_get_config;
396     vdc->set_status = vu_gpio_set_status;
397     vdc->guest_notifier_mask = vu_gpio_guest_notifier_mask;
398 }
399 
400 static const TypeInfo vu_gpio_info = {
401     .name = TYPE_VHOST_USER_GPIO,
402     .parent = TYPE_VIRTIO_DEVICE,
403     .instance_size = sizeof(VHostUserGPIO),
404     .class_init = vu_gpio_class_init,
405 };
406 
407 static void vu_gpio_register_types(void)
408 {
409     type_register_static(&vu_gpio_info);
410 }
411 
412 type_init(vu_gpio_register_types)
413