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 19 static bool is_guest_ready(VirtIORNG *vrng) 20 { 21 VirtIODevice *vdev = VIRTIO_DEVICE(vrng); 22 if (virtio_queue_ready(vrng->vq) 23 && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) { 24 return true; 25 } 26 return false; 27 } 28 29 static size_t get_request_size(VirtQueue *vq, unsigned quota) 30 { 31 unsigned int in, out; 32 33 virtqueue_get_avail_bytes(vq, &in, &out, quota, 0); 34 return in; 35 } 36 37 static void virtio_rng_process(VirtIORNG *vrng); 38 39 /* Send data from a char device over to the guest */ 40 static void chr_read(void *opaque, const void *buf, size_t size) 41 { 42 VirtIORNG *vrng = opaque; 43 VirtIODevice *vdev = VIRTIO_DEVICE(vrng); 44 VirtQueueElement elem; 45 size_t len; 46 int offset; 47 48 if (!is_guest_ready(vrng)) { 49 return; 50 } 51 52 vrng->quota_remaining -= size; 53 54 offset = 0; 55 while (offset < size) { 56 if (!virtqueue_pop(vrng->vq, &elem)) { 57 break; 58 } 59 len = iov_from_buf(elem.in_sg, elem.in_num, 60 0, buf + offset, size - offset); 61 offset += len; 62 63 virtqueue_push(vrng->vq, &elem, len); 64 } 65 virtio_notify(vdev, vrng->vq); 66 } 67 68 static void virtio_rng_process(VirtIORNG *vrng) 69 { 70 size_t size; 71 unsigned quota; 72 73 if (!is_guest_ready(vrng)) { 74 return; 75 } 76 77 if (vrng->quota_remaining < 0) { 78 quota = 0; 79 } else { 80 quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX); 81 } 82 size = get_request_size(vrng->vq, quota); 83 size = MIN(vrng->quota_remaining, size); 84 if (size) { 85 rng_backend_request_entropy(vrng->rng, size, chr_read, vrng); 86 } 87 } 88 89 static void handle_input(VirtIODevice *vdev, VirtQueue *vq) 90 { 91 VirtIORNG *vrng = VIRTIO_RNG(vdev); 92 virtio_rng_process(vrng); 93 } 94 95 static uint32_t get_features(VirtIODevice *vdev, uint32_t f) 96 { 97 return f; 98 } 99 100 static void virtio_rng_save(QEMUFile *f, void *opaque) 101 { 102 VirtIODevice *vdev = opaque; 103 104 virtio_save(vdev, f); 105 } 106 107 static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id) 108 { 109 VirtIORNG *vrng = opaque; 110 VirtIODevice *vdev = VIRTIO_DEVICE(vrng); 111 112 if (version_id != 1) { 113 return -EINVAL; 114 } 115 virtio_load(vdev, f); 116 117 /* We may have an element ready but couldn't process it due to a quota 118 * limit. Make sure to try again after live migration when the quota may 119 * have been reset. 120 */ 121 virtio_rng_process(vrng); 122 123 return 0; 124 } 125 126 static void check_rate_limit(void *opaque) 127 { 128 VirtIORNG *vrng = opaque; 129 130 vrng->quota_remaining = vrng->conf.max_bytes; 131 virtio_rng_process(vrng); 132 timer_mod(vrng->rate_limit_timer, 133 qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms); 134 } 135 136 static int virtio_rng_device_init(VirtIODevice *vdev) 137 { 138 DeviceState *qdev = DEVICE(vdev); 139 VirtIORNG *vrng = VIRTIO_RNG(vdev); 140 Error *local_err = NULL; 141 142 if (vrng->conf.rng == NULL) { 143 vrng->conf.default_backend = RNG_RANDOM(object_new(TYPE_RNG_RANDOM)); 144 145 object_property_add_child(OBJECT(qdev), 146 "default-backend", 147 OBJECT(vrng->conf.default_backend), 148 NULL); 149 150 object_property_set_link(OBJECT(qdev), 151 OBJECT(vrng->conf.default_backend), 152 "rng", NULL); 153 } 154 155 virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0); 156 157 vrng->rng = vrng->conf.rng; 158 if (vrng->rng == NULL) { 159 qerror_report(QERR_INVALID_PARAMETER_VALUE, "rng", "a valid object"); 160 return -1; 161 } 162 163 rng_backend_open(vrng->rng, &local_err); 164 if (local_err) { 165 qerror_report_err(local_err); 166 error_free(local_err); 167 return -1; 168 } 169 170 vrng->vq = virtio_add_queue(vdev, 8, handle_input); 171 172 assert(vrng->conf.max_bytes <= INT64_MAX); 173 vrng->quota_remaining = vrng->conf.max_bytes; 174 175 vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, 176 check_rate_limit, vrng); 177 178 timer_mod(vrng->rate_limit_timer, 179 qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms); 180 181 register_savevm(qdev, "virtio-rng", -1, 1, virtio_rng_save, 182 virtio_rng_load, vrng); 183 184 return 0; 185 } 186 187 static int virtio_rng_device_exit(DeviceState *qdev) 188 { 189 VirtIORNG *vrng = VIRTIO_RNG(qdev); 190 VirtIODevice *vdev = VIRTIO_DEVICE(qdev); 191 192 timer_del(vrng->rate_limit_timer); 193 timer_free(vrng->rate_limit_timer); 194 unregister_savevm(qdev, "virtio-rng", vrng); 195 virtio_cleanup(vdev); 196 return 0; 197 } 198 199 static Property virtio_rng_properties[] = { 200 DEFINE_VIRTIO_RNG_PROPERTIES(VirtIORNG, conf), 201 DEFINE_PROP_END_OF_LIST(), 202 }; 203 204 static void virtio_rng_class_init(ObjectClass *klass, void *data) 205 { 206 DeviceClass *dc = DEVICE_CLASS(klass); 207 VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass); 208 dc->exit = virtio_rng_device_exit; 209 dc->props = virtio_rng_properties; 210 set_bit(DEVICE_CATEGORY_MISC, dc->categories); 211 vdc->init = virtio_rng_device_init; 212 vdc->get_features = get_features; 213 } 214 215 static void virtio_rng_initfn(Object *obj) 216 { 217 VirtIORNG *vrng = VIRTIO_RNG(obj); 218 219 object_property_add_link(obj, "rng", TYPE_RNG_BACKEND, 220 (Object **)&vrng->conf.rng, NULL); 221 } 222 223 static const TypeInfo virtio_rng_info = { 224 .name = TYPE_VIRTIO_RNG, 225 .parent = TYPE_VIRTIO_DEVICE, 226 .instance_size = sizeof(VirtIORNG), 227 .instance_init = virtio_rng_initfn, 228 .class_init = virtio_rng_class_init, 229 }; 230 231 static void virtio_register_types(void) 232 { 233 type_register_static(&virtio_rng_info); 234 } 235 236 type_init(virtio_register_types) 237