| /* |
| * A virtio device implementing a hardware random number generator. |
| * |
| * Copyright 2012 Red Hat, Inc. |
| * Copyright 2012 Amit Shah <amit.shah@redhat.com> |
| * |
| * This work is licensed under the terms of the GNU GPL, version 2 or |
| * (at your option) any later version. See the COPYING file in the |
| * top-level directory. |
| */ |
| |
| #include "qemu/osdep.h" |
| #include "qapi/error.h" |
| #include "qemu/iov.h" |
| #include "qemu/module.h" |
| #include "qemu/timer.h" |
| #include "hw/virtio/virtio.h" |
| #include "hw/qdev-properties.h" |
| #include "hw/virtio/virtio-rng.h" |
| #include "sysemu/rng.h" |
| #include "sysemu/runstate.h" |
| #include "qom/object_interfaces.h" |
| #include "trace.h" |
| |
| static bool is_guest_ready(VirtIORNG *vrng) |
| { |
| VirtIODevice *vdev = VIRTIO_DEVICE(vrng); |
| if (virtio_queue_ready(vrng->vq) |
| && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) { |
| return true; |
| } |
| trace_virtio_rng_guest_not_ready(vrng); |
| return false; |
| } |
| |
| static size_t get_request_size(VirtQueue *vq, unsigned quota) |
| { |
| unsigned int in, out; |
| |
| virtqueue_get_avail_bytes(vq, &in, &out, quota, 0); |
| return in; |
| } |
| |
| static void virtio_rng_process(VirtIORNG *vrng); |
| |
| /* Send data from a char device over to the guest */ |
| static void chr_read(void *opaque, const void *buf, size_t size) |
| { |
| VirtIORNG *vrng = opaque; |
| VirtIODevice *vdev = VIRTIO_DEVICE(vrng); |
| VirtQueueElement *elem; |
| size_t len; |
| int offset; |
| |
| if (!is_guest_ready(vrng)) { |
| return; |
| } |
| |
| /* we can't modify the virtqueue until |
| * our state is fully synced |
| */ |
| |
| if (!runstate_check(RUN_STATE_RUNNING)) { |
| trace_virtio_rng_cpu_is_stopped(vrng, size); |
| return; |
| } |
| |
| vrng->quota_remaining -= size; |
| |
| offset = 0; |
| while (offset < size) { |
| elem = virtqueue_pop(vrng->vq, sizeof(VirtQueueElement)); |
| if (!elem) { |
| break; |
| } |
| trace_virtio_rng_popped(vrng); |
| len = iov_from_buf(elem->in_sg, elem->in_num, |
| 0, buf + offset, size - offset); |
| offset += len; |
| |
| virtqueue_push(vrng->vq, elem, len); |
| trace_virtio_rng_pushed(vrng, len); |
| g_free(elem); |
| } |
| virtio_notify(vdev, vrng->vq); |
| |
| if (!virtio_queue_empty(vrng->vq)) { |
| /* If we didn't drain the queue, call virtio_rng_process |
| * to take care of asking for more data as appropriate. |
| */ |
| virtio_rng_process(vrng); |
| } |
| } |
| |
| static void virtio_rng_process(VirtIORNG *vrng) |
| { |
| size_t size; |
| unsigned quota; |
| |
| if (!is_guest_ready(vrng)) { |
| return; |
| } |
| |
| if (vrng->activate_timer) { |
| timer_mod(vrng->rate_limit_timer, |
| qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms); |
| vrng->activate_timer = false; |
| } |
| |
| if (vrng->quota_remaining < 0) { |
| quota = 0; |
| } else { |
| quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX); |
| } |
| size = get_request_size(vrng->vq, quota); |
| |
| trace_virtio_rng_request(vrng, size, quota); |
| |
| size = MIN(vrng->quota_remaining, size); |
| if (size) { |
| rng_backend_request_entropy(vrng->rng, size, chr_read, vrng); |
| } |
| } |
| |
| static void handle_input(VirtIODevice *vdev, VirtQueue *vq) |
| { |
| VirtIORNG *vrng = VIRTIO_RNG(vdev); |
| virtio_rng_process(vrng); |
| } |
| |
| static uint64_t get_features(VirtIODevice *vdev, uint64_t f, Error **errp) |
| { |
| return f; |
| } |
| |
| static void virtio_rng_vm_state_change(void *opaque, int running, |
| RunState state) |
| { |
| VirtIORNG *vrng = opaque; |
| |
| trace_virtio_rng_vm_state_change(vrng, running, state); |
| |
| /* We may have an element ready but couldn't process it due to a quota |
| * limit or because CPU was stopped. Make sure to try again when the |
| * CPU restart. |
| */ |
| |
| if (running && is_guest_ready(vrng)) { |
| virtio_rng_process(vrng); |
| } |
| } |
| |
| static void check_rate_limit(void *opaque) |
| { |
| VirtIORNG *vrng = opaque; |
| |
| vrng->quota_remaining = vrng->conf.max_bytes; |
| virtio_rng_process(vrng); |
| vrng->activate_timer = true; |
| } |
| |
| static void virtio_rng_set_status(VirtIODevice *vdev, uint8_t status) |
| { |
| VirtIORNG *vrng = VIRTIO_RNG(vdev); |
| |
| if (!vdev->vm_running) { |
| return; |
| } |
| vdev->status = status; |
| |
| /* Something changed, try to process buffers */ |
| virtio_rng_process(vrng); |
| } |
| |
| static void virtio_rng_device_realize(DeviceState *dev, Error **errp) |
| { |
| VirtIODevice *vdev = VIRTIO_DEVICE(dev); |
| VirtIORNG *vrng = VIRTIO_RNG(dev); |
| Error *local_err = NULL; |
| |
| if (vrng->conf.period_ms <= 0) { |
| error_setg(errp, "'period' parameter expects a positive integer"); |
| return; |
| } |
| |
| /* Workaround: Property parsing does not enforce unsigned integers, |
| * So this is a hack to reject such numbers. */ |
| if (vrng->conf.max_bytes > INT64_MAX) { |
| error_setg(errp, "'max-bytes' parameter must be non-negative, " |
| "and less than 2^63"); |
| return; |
| } |
| |
| if (vrng->conf.rng == NULL) { |
| Object *default_backend = object_new(TYPE_RNG_BUILTIN); |
| |
| user_creatable_complete(USER_CREATABLE(default_backend), |
| &local_err); |
| if (local_err) { |
| error_propagate(errp, local_err); |
| object_unref(default_backend); |
| return; |
| } |
| |
| object_property_add_child(OBJECT(dev), "default-backend", |
| default_backend, &error_abort); |
| |
| /* The child property took a reference, we can safely drop ours now */ |
| object_unref(default_backend); |
| |
| object_property_set_link(OBJECT(dev), default_backend, |
| "rng", &error_abort); |
| } |
| |
| vrng->rng = vrng->conf.rng; |
| if (vrng->rng == NULL) { |
| error_setg(errp, "'rng' parameter expects a valid object"); |
| return; |
| } |
| |
| virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0); |
| |
| vrng->vq = virtio_add_queue(vdev, 8, handle_input); |
| vrng->quota_remaining = vrng->conf.max_bytes; |
| vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, |
| check_rate_limit, vrng); |
| vrng->activate_timer = true; |
| |
| vrng->vmstate = qemu_add_vm_change_state_handler(virtio_rng_vm_state_change, |
| vrng); |
| } |
| |
| static void virtio_rng_device_unrealize(DeviceState *dev, Error **errp) |
| { |
| VirtIODevice *vdev = VIRTIO_DEVICE(dev); |
| VirtIORNG *vrng = VIRTIO_RNG(dev); |
| |
| qemu_del_vm_change_state_handler(vrng->vmstate); |
| timer_del(vrng->rate_limit_timer); |
| timer_free(vrng->rate_limit_timer); |
| virtio_del_queue(vdev, 0); |
| virtio_cleanup(vdev); |
| } |
| |
| static const VMStateDescription vmstate_virtio_rng = { |
| .name = "virtio-rng", |
| .minimum_version_id = 1, |
| .version_id = 1, |
| .fields = (VMStateField[]) { |
| VMSTATE_VIRTIO_DEVICE, |
| VMSTATE_END_OF_LIST() |
| }, |
| }; |
| |
| static Property virtio_rng_properties[] = { |
| /* Set a default rate limit of 2^47 bytes per minute or roughly 2TB/s. If |
| * you have an entropy source capable of generating more entropy than this |
| * and you can pass it through via virtio-rng, then hats off to you. Until |
| * then, this is unlimited for all practical purposes. |
| */ |
| DEFINE_PROP_UINT64("max-bytes", VirtIORNG, conf.max_bytes, INT64_MAX), |
| DEFINE_PROP_UINT32("period", VirtIORNG, conf.period_ms, 1 << 16), |
| DEFINE_PROP_LINK("rng", VirtIORNG, conf.rng, TYPE_RNG_BACKEND, RngBackend *), |
| DEFINE_PROP_END_OF_LIST(), |
| }; |
| |
| static void virtio_rng_class_init(ObjectClass *klass, void *data) |
| { |
| DeviceClass *dc = DEVICE_CLASS(klass); |
| VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass); |
| |
| device_class_set_props(dc, virtio_rng_properties); |
| dc->vmsd = &vmstate_virtio_rng; |
| set_bit(DEVICE_CATEGORY_MISC, dc->categories); |
| vdc->realize = virtio_rng_device_realize; |
| vdc->unrealize = virtio_rng_device_unrealize; |
| vdc->get_features = get_features; |
| vdc->set_status = virtio_rng_set_status; |
| } |
| |
| static const TypeInfo virtio_rng_info = { |
| .name = TYPE_VIRTIO_RNG, |
| .parent = TYPE_VIRTIO_DEVICE, |
| .instance_size = sizeof(VirtIORNG), |
| .class_init = virtio_rng_class_init, |
| }; |
| |
| static void virtio_register_types(void) |
| { |
| type_register_static(&virtio_rng_info); |
| } |
| |
| type_init(virtio_register_types) |