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_setg(errp, "'period' parameter expects a positive integer"); 146 return; 147 } 148 149 /* Workaround: Property parsing does not enforce unsigned integers, 150 * So this is a hack to reject such numbers. */ 151 if (vrng->conf.max_bytes > INT64_MAX) { 152 error_setg(errp, "'max-bytes' parameter must be non-negative, " 153 "and less than 2^63"); 154 return; 155 } 156 157 if (vrng->conf.rng == NULL) { 158 vrng->conf.default_backend = RNG_RANDOM(object_new(TYPE_RNG_RANDOM)); 159 160 user_creatable_complete(OBJECT(vrng->conf.default_backend), 161 &local_err); 162 if (local_err) { 163 error_propagate(errp, local_err); 164 object_unref(OBJECT(vrng->conf.default_backend)); 165 return; 166 } 167 168 object_property_add_child(OBJECT(dev), 169 "default-backend", 170 OBJECT(vrng->conf.default_backend), 171 NULL); 172 173 /* The child property took a reference, we can safely drop ours now */ 174 object_unref(OBJECT(vrng->conf.default_backend)); 175 176 object_property_set_link(OBJECT(dev), 177 OBJECT(vrng->conf.default_backend), 178 "rng", NULL); 179 } 180 181 vrng->rng = vrng->conf.rng; 182 if (vrng->rng == NULL) { 183 error_setg(errp, "'rng' parameter expects a valid object"); 184 return; 185 } 186 187 virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0); 188 189 vrng->vq = virtio_add_queue(vdev, 8, handle_input); 190 vrng->quota_remaining = vrng->conf.max_bytes; 191 192 vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, 193 check_rate_limit, vrng); 194 195 timer_mod(vrng->rate_limit_timer, 196 qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms); 197 198 register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save, 199 virtio_rng_load, vrng); 200 } 201 202 static void virtio_rng_device_unrealize(DeviceState *dev, Error **errp) 203 { 204 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 205 VirtIORNG *vrng = VIRTIO_RNG(dev); 206 207 timer_del(vrng->rate_limit_timer); 208 timer_free(vrng->rate_limit_timer); 209 unregister_savevm(dev, "virtio-rng", vrng); 210 virtio_cleanup(vdev); 211 } 212 213 static Property virtio_rng_properties[] = { 214 DEFINE_VIRTIO_RNG_PROPERTIES(VirtIORNG, conf), 215 DEFINE_PROP_END_OF_LIST(), 216 }; 217 218 static void virtio_rng_class_init(ObjectClass *klass, void *data) 219 { 220 DeviceClass *dc = DEVICE_CLASS(klass); 221 VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass); 222 223 dc->props = virtio_rng_properties; 224 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 225 vdc->realize = virtio_rng_device_realize; 226 vdc->unrealize = virtio_rng_device_unrealize; 227 vdc->get_features = get_features; 228 vdc->load = virtio_rng_load_device; 229 } 230 231 static void virtio_rng_initfn(Object *obj) 232 { 233 VirtIORNG *vrng = VIRTIO_RNG(obj); 234 235 object_property_add_link(obj, "rng", TYPE_RNG_BACKEND, 236 (Object **)&vrng->conf.rng, 237 qdev_prop_allow_set_link_before_realize, 238 OBJ_PROP_LINK_UNREF_ON_RELEASE, NULL); 239 } 240 241 static const TypeInfo virtio_rng_info = { 242 .name = TYPE_VIRTIO_RNG, 243 .parent = TYPE_VIRTIO_DEVICE, 244 .instance_size = sizeof(VirtIORNG), 245 .instance_init = virtio_rng_initfn, 246 .class_init = virtio_rng_class_init, 247 }; 248 249 static void virtio_register_types(void) 250 { 251 type_register_static(&virtio_rng_info); 252 } 253 254 type_init(virtio_register_types) 255