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 VirtIORNG *vrng = opaque; 111 VirtIODevice *vdev = VIRTIO_DEVICE(vrng); 112 113 if (version_id != 1) { 114 return -EINVAL; 115 } 116 virtio_load(vdev, f); 117 118 /* We may have an element ready but couldn't process it due to a quota 119 * limit. Make sure to try again after live migration when the quota may 120 * have been reset. 121 */ 122 virtio_rng_process(vrng); 123 124 return 0; 125 } 126 127 static void check_rate_limit(void *opaque) 128 { 129 VirtIORNG *vrng = opaque; 130 131 vrng->quota_remaining = vrng->conf.max_bytes; 132 virtio_rng_process(vrng); 133 timer_mod(vrng->rate_limit_timer, 134 qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms); 135 } 136 137 static void virtio_rng_device_realize(DeviceState *dev, Error **errp) 138 { 139 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 140 VirtIORNG *vrng = VIRTIO_RNG(dev); 141 Error *local_err = NULL; 142 143 if (!vrng->conf.period_ms > 0) { 144 error_set(errp, QERR_INVALID_PARAMETER_VALUE, "period", 145 "a positive number"); 146 return; 147 } 148 149 if (vrng->conf.rng == NULL) { 150 vrng->conf.default_backend = RNG_RANDOM(object_new(TYPE_RNG_RANDOM)); 151 152 user_creatable_complete(OBJECT(vrng->conf.default_backend), 153 &local_err); 154 if (local_err) { 155 error_propagate(errp, local_err); 156 object_unref(OBJECT(vrng->conf.default_backend)); 157 return; 158 } 159 160 object_property_add_child(OBJECT(dev), 161 "default-backend", 162 OBJECT(vrng->conf.default_backend), 163 NULL); 164 165 /* The child property took a reference, we can safely drop ours now */ 166 object_unref(OBJECT(vrng->conf.default_backend)); 167 168 object_property_set_link(OBJECT(dev), 169 OBJECT(vrng->conf.default_backend), 170 "rng", NULL); 171 } 172 173 virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0); 174 175 vrng->rng = vrng->conf.rng; 176 if (vrng->rng == NULL) { 177 error_set(errp, QERR_INVALID_PARAMETER_VALUE, "rng", "a valid object"); 178 return; 179 } 180 181 vrng->vq = virtio_add_queue(vdev, 8, handle_input); 182 183 assert(vrng->conf.max_bytes <= INT64_MAX); 184 vrng->quota_remaining = vrng->conf.max_bytes; 185 186 vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, 187 check_rate_limit, vrng); 188 189 timer_mod(vrng->rate_limit_timer, 190 qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms); 191 192 register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save, 193 virtio_rng_load, vrng); 194 } 195 196 static void virtio_rng_device_unrealize(DeviceState *dev, Error **errp) 197 { 198 VirtIODevice *vdev = VIRTIO_DEVICE(dev); 199 VirtIORNG *vrng = VIRTIO_RNG(dev); 200 201 timer_del(vrng->rate_limit_timer); 202 timer_free(vrng->rate_limit_timer); 203 unregister_savevm(dev, "virtio-rng", vrng); 204 virtio_cleanup(vdev); 205 } 206 207 static Property virtio_rng_properties[] = { 208 DEFINE_VIRTIO_RNG_PROPERTIES(VirtIORNG, conf), 209 DEFINE_PROP_END_OF_LIST(), 210 }; 211 212 static void virtio_rng_class_init(ObjectClass *klass, void *data) 213 { 214 DeviceClass *dc = DEVICE_CLASS(klass); 215 VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass); 216 217 dc->props = virtio_rng_properties; 218 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 219 vdc->realize = virtio_rng_device_realize; 220 vdc->unrealize = virtio_rng_device_unrealize; 221 vdc->get_features = get_features; 222 } 223 224 static void virtio_rng_initfn(Object *obj) 225 { 226 VirtIORNG *vrng = VIRTIO_RNG(obj); 227 228 object_property_add_link(obj, "rng", TYPE_RNG_BACKEND, 229 (Object **)&vrng->conf.rng, 230 qdev_prop_allow_set_link_before_realize, 231 OBJ_PROP_LINK_UNREF_ON_RELEASE, NULL); 232 } 233 234 static const TypeInfo virtio_rng_info = { 235 .name = TYPE_VIRTIO_RNG, 236 .parent = TYPE_VIRTIO_DEVICE, 237 .instance_size = sizeof(VirtIORNG), 238 .instance_init = virtio_rng_initfn, 239 .class_init = virtio_rng_class_init, 240 }; 241 242 static void virtio_register_types(void) 243 { 244 type_register_static(&virtio_rng_info); 245 } 246 247 type_init(virtio_register_types) 248