1 /* 2 * A virtio device implementing a hardware random number generator. 3 * 4 * Copyright 2012 Red Hat, Inc. 5 * Copyright 2012 Amit Shah <amit.shah@redhat.com> 6 * 7 * This work is licensed under the terms of the GNU GPL, version 2 or 8 * (at your option) any later version. See the COPYING file in the 9 * top-level directory. 10 */ 11 12 #include "qemu/iov.h" 13 #include "hw/qdev.h" 14 #include "qapi/qmp/qerror.h" 15 #include "hw/virtio/virtio.h" 16 #include "hw/virtio/virtio-rng.h" 17 #include "sysemu/rng.h" 18 #include "qom/object_interfaces.h" 19 20 static bool is_guest_ready(VirtIORNG *vrng) 21 { 22 VirtIODevice *vdev = VIRTIO_DEVICE(vrng); 23 if (virtio_queue_ready(vrng->vq) 24 && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) { 25 return true; 26 } 27 return false; 28 } 29 30 static size_t get_request_size(VirtQueue *vq, unsigned quota) 31 { 32 unsigned int in, out; 33 34 virtqueue_get_avail_bytes(vq, &in, &out, quota, 0); 35 return in; 36 } 37 38 static void virtio_rng_process(VirtIORNG *vrng); 39 40 /* Send data from a char device over to the guest */ 41 static void chr_read(void *opaque, const void *buf, size_t size) 42 { 43 VirtIORNG *vrng = opaque; 44 VirtIODevice *vdev = VIRTIO_DEVICE(vrng); 45 VirtQueueElement elem; 46 size_t len; 47 int offset; 48 49 if (!is_guest_ready(vrng)) { 50 return; 51 } 52 53 vrng->quota_remaining -= size; 54 55 offset = 0; 56 while (offset < size) { 57 if (!virtqueue_pop(vrng->vq, &elem)) { 58 break; 59 } 60 len = iov_from_buf(elem.in_sg, elem.in_num, 61 0, buf + offset, size - offset); 62 offset += len; 63 64 virtqueue_push(vrng->vq, &elem, len); 65 } 66 virtio_notify(vdev, vrng->vq); 67 } 68 69 static void virtio_rng_process(VirtIORNG *vrng) 70 { 71 size_t size; 72 unsigned quota; 73 74 if (!is_guest_ready(vrng)) { 75 return; 76 } 77 78 if (vrng->quota_remaining < 0) { 79 quota = 0; 80 } else { 81 quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX); 82 } 83 size = get_request_size(vrng->vq, quota); 84 size = MIN(vrng->quota_remaining, size); 85 if (size) { 86 rng_backend_request_entropy(vrng->rng, size, chr_read, vrng); 87 } 88 } 89 90 static void handle_input(VirtIODevice *vdev, VirtQueue *vq) 91 { 92 VirtIORNG *vrng = VIRTIO_RNG(vdev); 93 virtio_rng_process(vrng); 94 } 95 96 static uint32_t get_features(VirtIODevice *vdev, uint32_t f) 97 { 98 return f; 99 } 100 101 static void virtio_rng_save(QEMUFile *f, void *opaque) 102 { 103 VirtIODevice *vdev = opaque; 104 105 virtio_save(vdev, f); 106 } 107 108 static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id) 109 { 110 if (version_id != 1) { 111 return -EINVAL; 112 } 113 return virtio_load(VIRTIO_DEVICE(opaque), f, version_id); 114 } 115 116 static int virtio_rng_load_device(VirtIODevice *vdev, QEMUFile *f, 117 int version_id) 118 { 119 /* We may have an element ready but couldn't process it due to a quota 120 * limit. Make sure to try again after live migration when the quota may 121 * have been reset. 122 */ 123 virtio_rng_process(VIRTIO_RNG(vdev)); 124 125 return 0; 126 } 127 128 static void check_rate_limit(void *opaque) 129 { 130 VirtIORNG *vrng = opaque; 131 132 vrng->quota_remaining = vrng->conf.max_bytes; 133 virtio_rng_process(vrng); 134 timer_mod(vrng->rate_limit_timer, 135 qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms); 136 } 137 138 static void virtio_rng_device_realize(DeviceState *dev, Error **errp) 139 { 140 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 141 VirtIORNG *vrng = VIRTIO_RNG(dev); 142 Error *local_err = NULL; 143 144 if (!vrng->conf.period_ms > 0) { 145 error_set(errp, QERR_INVALID_PARAMETER_VALUE, "period", 146 "a positive number"); 147 return; 148 } 149 150 if (vrng->conf.rng == NULL) { 151 vrng->conf.default_backend = RNG_RANDOM(object_new(TYPE_RNG_RANDOM)); 152 153 user_creatable_complete(OBJECT(vrng->conf.default_backend), 154 &local_err); 155 if (local_err) { 156 error_propagate(errp, local_err); 157 object_unref(OBJECT(vrng->conf.default_backend)); 158 return; 159 } 160 161 object_property_add_child(OBJECT(dev), 162 "default-backend", 163 OBJECT(vrng->conf.default_backend), 164 NULL); 165 166 /* The child property took a reference, we can safely drop ours now */ 167 object_unref(OBJECT(vrng->conf.default_backend)); 168 169 object_property_set_link(OBJECT(dev), 170 OBJECT(vrng->conf.default_backend), 171 "rng", NULL); 172 } 173 174 virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0); 175 176 vrng->rng = vrng->conf.rng; 177 if (vrng->rng == NULL) { 178 error_set(errp, QERR_INVALID_PARAMETER_VALUE, "rng", "a valid object"); 179 return; 180 } 181 182 vrng->vq = virtio_add_queue(vdev, 8, handle_input); 183 184 assert(vrng->conf.max_bytes <= INT64_MAX); 185 vrng->quota_remaining = vrng->conf.max_bytes; 186 187 vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, 188 check_rate_limit, vrng); 189 190 timer_mod(vrng->rate_limit_timer, 191 qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms); 192 193 register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save, 194 virtio_rng_load, vrng); 195 } 196 197 static void virtio_rng_device_unrealize(DeviceState *dev, Error **errp) 198 { 199 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 200 VirtIORNG *vrng = VIRTIO_RNG(dev); 201 202 timer_del(vrng->rate_limit_timer); 203 timer_free(vrng->rate_limit_timer); 204 unregister_savevm(dev, "virtio-rng", vrng); 205 virtio_cleanup(vdev); 206 } 207 208 static Property virtio_rng_properties[] = { 209 DEFINE_VIRTIO_RNG_PROPERTIES(VirtIORNG, conf), 210 DEFINE_PROP_END_OF_LIST(), 211 }; 212 213 static void virtio_rng_class_init(ObjectClass *klass, void *data) 214 { 215 DeviceClass *dc = DEVICE_CLASS(klass); 216 VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass); 217 218 dc->props = virtio_rng_properties; 219 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 220 vdc->realize = virtio_rng_device_realize; 221 vdc->unrealize = virtio_rng_device_unrealize; 222 vdc->get_features = get_features; 223 vdc->load = virtio_rng_load_device; 224 } 225 226 static void virtio_rng_initfn(Object *obj) 227 { 228 VirtIORNG *vrng = VIRTIO_RNG(obj); 229 230 object_property_add_link(obj, "rng", TYPE_RNG_BACKEND, 231 (Object **)&vrng->conf.rng, 232 qdev_prop_allow_set_link_before_realize, 233 OBJ_PROP_LINK_UNREF_ON_RELEASE, NULL); 234 } 235 236 static const TypeInfo virtio_rng_info = { 237 .name = TYPE_VIRTIO_RNG, 238 .parent = TYPE_VIRTIO_DEVICE, 239 .instance_size = sizeof(VirtIORNG), 240 .instance_init = virtio_rng_initfn, 241 .class_init = virtio_rng_class_init, 242 }; 243 244 static void virtio_register_types(void) 245 { 246 type_register_static(&virtio_rng_info); 247 } 248 249 type_init(virtio_register_types) 250