hw/virtio/vhost-user-rng.c

   1 /*
   2  * Vhost-user RNG virtio device
   3  *
   4  * Copyright (c) 2021 Mathieu Poirier <mathieu.poirier@linaro.org>
   5  *
   6  * Implementation seriously tailored on vhost-user-i2c.c
   7  *
   8  * SPDX-License-Identifier: GPL-2.0-or-later
   9  */
  10
  11 #include "qemu/osdep.h"
  12 #include "qapi/error.h"
  13 #include "hw/qdev-properties.h"
  14 #include "hw/virtio/virtio-bus.h"
  15 #include "hw/virtio/vhost-user-rng.h"
  16 #include "qemu/error-report.h"
  17 #include "standard-headers/linux/virtio_ids.h"
  18
  19 static void vu_rng_start(VirtIODevice *vdev)
  20 {
  21     VHostUserRNG *rng = VHOST_USER_RNG(vdev);
  22     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
  23     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
  24     int ret;
  25     int i;
  26
  27     if (!k->set_guest_notifiers) {
  28         error_report("binding does not support guest notifiers");
  29         return;
  30     }
  31
  32     ret = vhost_dev_enable_notifiers(&rng->vhost_dev, vdev);
  33     if (ret < 0) {
  34         error_report("Error enabling host notifiers: %d", -ret);
  35         return;
  36     }
  37
  38     ret = k->set_guest_notifiers(qbus->parent, rng->vhost_dev.nvqs, true);
  39     if (ret < 0) {
  40         error_report("Error binding guest notifier: %d", -ret);
  41         goto err_host_notifiers;
  42     }
  43
  44     rng->vhost_dev.acked_features = vdev->guest_features;
  45     ret = vhost_dev_start(&rng->vhost_dev, vdev);
  46     if (ret < 0) {
  47         error_report("Error starting vhost-user-rng: %d", -ret);
  48         goto err_guest_notifiers;
  49     }
  50
  51     /*
  52      * guest_notifier_mask/pending not used yet, so just unmask
  53      * everything here. virtio-pci will do the right thing by
  54      * enabling/disabling irqfd.
  55      */
  56     for (i = 0; i < rng->vhost_dev.nvqs; i++) {
  57         vhost_virtqueue_mask(&rng->vhost_dev, vdev, i, false);
  58     }
  59
  60     return;
  61
  62 err_guest_notifiers:
  63     k->set_guest_notifiers(qbus->parent, rng->vhost_dev.nvqs, false);
  64 err_host_notifiers:
  65     vhost_dev_disable_notifiers(&rng->vhost_dev, vdev);
  66 }
  67
  68 static void vu_rng_stop(VirtIODevice *vdev)
  69 {
  70     VHostUserRNG *rng = VHOST_USER_RNG(vdev);
  71     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
  72     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
  73     int ret;
  74
  75     if (!k->set_guest_notifiers) {
  76         return;
  77     }
  78
  79     vhost_dev_stop(&rng->vhost_dev, vdev);
  80
  81     ret = k->set_guest_notifiers(qbus->parent, rng->vhost_dev.nvqs, false);
  82     if (ret < 0) {
  83         error_report("vhost guest notifier cleanup failed: %d", ret);
  84         return;
  85     }
  86
  87     vhost_dev_disable_notifiers(&rng->vhost_dev, vdev);
  88 }
  89
  90 static void vu_rng_set_status(VirtIODevice *vdev, uint8_t status)
  91 {
  92     VHostUserRNG *rng = VHOST_USER_RNG(vdev);
  93     bool should_start = status & VIRTIO_CONFIG_S_DRIVER_OK;
  94
  95     if (!vdev->vm_running) {
  96         should_start = false;
  97     }
  98
  99     if (rng->vhost_dev.started == should_start) {
 100         return;
 101     }
 102
 103     if (should_start) {
 104         vu_rng_start(vdev);
 105     } else {
 106         vu_rng_stop(vdev);
 107     }
 108 }
 109
 110 static uint64_t vu_rng_get_features(VirtIODevice *vdev,
 111                                     uint64_t requested_features, Error **errp)
 112 {
 113     /* No feature bits used yet */
 114     return requested_features;
 115 }
 116
 117 static void vu_rng_handle_output(VirtIODevice *vdev, VirtQueue *vq)
 118 {
 119     /*
 120      * Not normally called; it's the daemon that handles the queue;
 121      * however virtio's cleanup path can call this.
 122      */
 123 }
 124
 125 static void vu_rng_guest_notifier_mask(VirtIODevice *vdev, int idx, bool mask)
 126 {
 127     VHostUserRNG *rng = VHOST_USER_RNG(vdev);
 128
 129     vhost_virtqueue_mask(&rng->vhost_dev, vdev, idx, mask);
 130 }
 131
 132 static bool vu_rng_guest_notifier_pending(VirtIODevice *vdev, int idx)
 133 {
 134     VHostUserRNG *rng = VHOST_USER_RNG(vdev);
 135
 136     return vhost_virtqueue_pending(&rng->vhost_dev, idx);
 137 }
 138
 139 static void vu_rng_connect(DeviceState *dev)
 140 {
 141     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
 142     VHostUserRNG *rng = VHOST_USER_RNG(vdev);
 143
 144     if (rng->connected) {
 145         return;
 146     }
 147
 148     rng->connected = true;
 149
 150     /* restore vhost state */
 151     if (virtio_device_started(vdev, vdev->status)) {
 152         vu_rng_start(vdev);
 153     }
 154 }
 155
 156 static void vu_rng_disconnect(DeviceState *dev)
 157 {
 158     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
 159     VHostUserRNG *rng = VHOST_USER_RNG(vdev);
 160
 161     if (!rng->connected) {
 162         return;
 163     }
 164
 165     rng->connected = false;
 166
 167     if (rng->vhost_dev.started) {
 168         vu_rng_stop(vdev);
 169     }
 170 }
 171
 172 static void vu_rng_event(void *opaque, QEMUChrEvent event)
 173 {
 174     DeviceState *dev = opaque;
 175
 176     switch (event) {
 177     case CHR_EVENT_OPENED:
 178         vu_rng_connect(dev);
 179         break;
 180     case CHR_EVENT_CLOSED:
 181         vu_rng_disconnect(dev);
 182         break;
 183     case CHR_EVENT_BREAK:
 184     case CHR_EVENT_MUX_IN:
 185     case CHR_EVENT_MUX_OUT:
 186         /* Ignore */
 187         break;
 188     }
 189 }
 190
 191 static void vu_rng_device_realize(DeviceState *dev, Error **errp)
 192 {
 193     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
 194     VHostUserRNG *rng = VHOST_USER_RNG(dev);
 195     int ret;
 196
 197     if (!rng->chardev.chr) {
 198         error_setg(errp, "missing chardev");
 199         return;
 200     }
 201
 202     if (!vhost_user_init(&rng->vhost_user, &rng->chardev, errp)) {
 203         return;
 204     }
 205
 206     virtio_init(vdev, "vhost-user-rng", VIRTIO_ID_RNG, 0);
 207
 208     rng->req_vq = virtio_add_queue(vdev, 4, vu_rng_handle_output);
 209     if (!rng->req_vq) {
 210         error_setg_errno(errp, -1, "virtio_add_queue() failed");
 211         goto virtio_add_queue_failed;
 212     }
 213
 214     rng->vhost_dev.nvqs = 1;
 215     rng->vhost_dev.vqs = g_new0(struct vhost_virtqueue, rng->vhost_dev.nvqs);
 216     ret = vhost_dev_init(&rng->vhost_dev, &rng->vhost_user,
 217                          VHOST_BACKEND_TYPE_USER, 0, errp);
 218     if (ret < 0) {
 219         error_setg_errno(errp, -ret, "vhost_dev_init() failed");
 220         goto vhost_dev_init_failed;
 221     }
 222
 223     qemu_chr_fe_set_handlers(&rng->chardev, NULL, NULL, vu_rng_event, NULL,
 224                              dev, NULL, true);
 225
 226     return;
 227
 228 vhost_dev_init_failed:
 229     virtio_delete_queue(rng->req_vq);
 230 virtio_add_queue_failed:
 231     virtio_cleanup(vdev);
 232     vhost_user_cleanup(&rng->vhost_user);
 233 }
 234
 235 static void vu_rng_device_unrealize(DeviceState *dev)
 236 {
 237     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
 238     VHostUserRNG *rng = VHOST_USER_RNG(dev);
 239
 240     vu_rng_set_status(vdev, 0);
 241
 242     vhost_dev_cleanup(&rng->vhost_dev);
 243     g_free(rng->vhost_dev.vqs);
 244     rng->vhost_dev.vqs = NULL;
 245     virtio_delete_queue(rng->req_vq);
 246     virtio_cleanup(vdev);
 247     vhost_user_cleanup(&rng->vhost_user);
 248 }
 249
 250 static const VMStateDescription vu_rng_vmstate = {
 251     .name = "vhost-user-rng",
 252     .unmigratable = 1,
 253 };
 254
 255 static Property vu_rng_properties[] = {
 256     DEFINE_PROP_CHR("chardev", VHostUserRNG, chardev),
 257     DEFINE_PROP_END_OF_LIST(),
 258 };
 259
 260 static void vu_rng_class_init(ObjectClass *klass, void *data)
 261 {
 262     DeviceClass *dc = DEVICE_CLASS(klass);
 263     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
 264
 265     device_class_set_props(dc, vu_rng_properties);
 266     dc->vmsd = &vu_rng_vmstate;
 267     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
 268
 269     vdc->realize = vu_rng_device_realize;
 270     vdc->unrealize = vu_rng_device_unrealize;
 271     vdc->get_features = vu_rng_get_features;
 272     vdc->set_status = vu_rng_set_status;
 273     vdc->guest_notifier_mask = vu_rng_guest_notifier_mask;
 274     vdc->guest_notifier_pending = vu_rng_guest_notifier_pending;
 275 }
 276
 277 static const TypeInfo vu_rng_info = {
 278     .name = TYPE_VHOST_USER_RNG,
 279     .parent = TYPE_VIRTIO_DEVICE,
 280     .instance_size = sizeof(VHostUserRNG),
 281     .class_init = vu_rng_class_init,
 282 };
 283
 284 static void vu_rng_register_types(void)
 285 {
 286     type_register_static(&vu_rng_info);
 287 }
 288
 289 type_init(vu_rng_register_types)