| /* |
| * 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 "iov.h" |
| #include "qdev.h" |
| #include "virtio.h" |
| #include "virtio-rng.h" |
| #include "qemu/rng.h" |
| |
| typedef struct VirtIORNG { |
| VirtIODevice vdev; |
| |
| DeviceState *qdev; |
| |
| /* Only one vq - guest puts buffer(s) on it when it needs entropy */ |
| VirtQueue *vq; |
| VirtQueueElement elem; |
| |
| /* Config data for the device -- currently only chardev */ |
| VirtIORNGConf *conf; |
| |
| /* Whether we've popped a vq element into 'elem' above */ |
| bool popped; |
| |
| RngBackend *rng; |
| |
| /* We purposefully don't migrate this state. The quota will reset on the |
| * destination as a result. Rate limiting is host state, not guest state. |
| */ |
| QEMUTimer *rate_limit_timer; |
| int64_t quota_remaining; |
| } VirtIORNG; |
| |
| static bool is_guest_ready(VirtIORNG *vrng) |
| { |
| if (virtio_queue_ready(vrng->vq) |
| && (vrng->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK)) { |
| return true; |
| } |
| return false; |
| } |
| |
| static size_t pop_an_elem(VirtIORNG *vrng) |
| { |
| size_t size; |
| |
| if (!vrng->popped && !virtqueue_pop(vrng->vq, &vrng->elem)) { |
| return 0; |
| } |
| vrng->popped = true; |
| |
| size = iov_size(vrng->elem.in_sg, vrng->elem.in_num); |
| return size; |
| } |
| |
| 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; |
| size_t len; |
| int offset; |
| |
| if (!is_guest_ready(vrng)) { |
| return; |
| } |
| |
| vrng->quota_remaining -= size; |
| |
| offset = 0; |
| while (offset < size) { |
| if (!pop_an_elem(vrng)) { |
| break; |
| } |
| len = iov_from_buf(vrng->elem.in_sg, vrng->elem.in_num, |
| 0, buf + offset, size - offset); |
| offset += len; |
| |
| virtqueue_push(vrng->vq, &vrng->elem, len); |
| vrng->popped = false; |
| } |
| virtio_notify(&vrng->vdev, vrng->vq); |
| |
| /* |
| * Lastly, if we had multiple elems queued by the guest, and we |
| * didn't have enough data to fill them all, indicate we want more |
| * data. |
| */ |
| virtio_rng_process(vrng); |
| } |
| |
| static void virtio_rng_process(VirtIORNG *vrng) |
| { |
| ssize_t size; |
| |
| if (!is_guest_ready(vrng)) { |
| return; |
| } |
| |
| size = pop_an_elem(vrng); |
| size = MIN(vrng->quota_remaining, size); |
| |
| if (size > 0) { |
| rng_backend_request_entropy(vrng->rng, size, chr_read, vrng); |
| } |
| } |
| |
| |
| static void handle_input(VirtIODevice *vdev, VirtQueue *vq) |
| { |
| VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev); |
| virtio_rng_process(vrng); |
| } |
| |
| static uint32_t get_features(VirtIODevice *vdev, uint32_t f) |
| { |
| return f; |
| } |
| |
| static void virtio_rng_save(QEMUFile *f, void *opaque) |
| { |
| VirtIORNG *vrng = opaque; |
| |
| virtio_save(&vrng->vdev, f); |
| |
| qemu_put_byte(f, vrng->popped); |
| if (vrng->popped) { |
| int i; |
| |
| qemu_put_be32(f, vrng->elem.index); |
| |
| qemu_put_be32(f, vrng->elem.in_num); |
| for (i = 0; i < vrng->elem.in_num; i++) { |
| qemu_put_be64(f, vrng->elem.in_addr[i]); |
| } |
| |
| qemu_put_be32(f, vrng->elem.out_num); |
| for (i = 0; i < vrng->elem.out_num; i++) { |
| qemu_put_be64(f, vrng->elem.out_addr[i]); |
| } |
| } |
| } |
| |
| static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id) |
| { |
| VirtIORNG *vrng = opaque; |
| |
| if (version_id != 1) { |
| return -EINVAL; |
| } |
| virtio_load(&vrng->vdev, f); |
| |
| vrng->popped = qemu_get_byte(f); |
| if (vrng->popped) { |
| int i; |
| |
| vrng->elem.index = qemu_get_be32(f); |
| |
| vrng->elem.in_num = qemu_get_be32(f); |
| g_assert(vrng->elem.in_num < VIRTQUEUE_MAX_SIZE); |
| for (i = 0; i < vrng->elem.in_num; i++) { |
| vrng->elem.in_addr[i] = qemu_get_be64(f); |
| } |
| |
| vrng->elem.out_num = qemu_get_be32(f); |
| g_assert(vrng->elem.out_num < VIRTQUEUE_MAX_SIZE); |
| for (i = 0; i < vrng->elem.out_num; i++) { |
| vrng->elem.out_addr[i] = qemu_get_be64(f); |
| } |
| |
| virtqueue_map_sg(vrng->elem.in_sg, vrng->elem.in_addr, |
| vrng->elem.in_num, 1); |
| virtqueue_map_sg(vrng->elem.out_sg, vrng->elem.out_addr, |
| vrng->elem.out_num, 0); |
| } |
| |
| /* We may have an element ready but couldn't process it due to a quota |
| limit. Make sure to try again after live migration when the quota may |
| have been reset. |
| */ |
| virtio_rng_process(vrng); |
| |
| return 0; |
| } |
| |
| static void check_rate_limit(void *opaque) |
| { |
| VirtIORNG *s = opaque; |
| |
| s->quota_remaining = s->conf->max_bytes; |
| virtio_rng_process(s); |
| qemu_mod_timer(s->rate_limit_timer, |
| qemu_get_clock_ms(vm_clock) + s->conf->period_ms); |
| } |
| |
| |
| VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf) |
| { |
| VirtIORNG *vrng; |
| VirtIODevice *vdev; |
| Error *local_err = NULL; |
| |
| vdev = virtio_common_init("virtio-rng", VIRTIO_ID_RNG, 0, |
| sizeof(VirtIORNG)); |
| |
| vrng = DO_UPCAST(VirtIORNG, vdev, vdev); |
| |
| vrng->rng = conf->rng; |
| if (vrng->rng == NULL) { |
| qerror_report(QERR_INVALID_PARAMETER_VALUE, "rng", "a valid object"); |
| return NULL; |
| } |
| |
| rng_backend_open(vrng->rng, &local_err); |
| if (local_err) { |
| qerror_report_err(local_err); |
| error_free(local_err); |
| return NULL; |
| } |
| |
| vrng->vq = virtio_add_queue(vdev, 8, handle_input); |
| vrng->vdev.get_features = get_features; |
| |
| vrng->qdev = dev; |
| vrng->conf = conf; |
| vrng->popped = false; |
| vrng->quota_remaining = vrng->conf->max_bytes; |
| |
| g_assert_cmpint(vrng->conf->max_bytes, <=, INT64_MAX); |
| |
| vrng->rate_limit_timer = qemu_new_timer_ms(vm_clock, |
| check_rate_limit, vrng); |
| |
| qemu_mod_timer(vrng->rate_limit_timer, |
| qemu_get_clock_ms(vm_clock) + vrng->conf->period_ms); |
| |
| register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save, |
| virtio_rng_load, vrng); |
| |
| return vdev; |
| } |
| |
| void virtio_rng_exit(VirtIODevice *vdev) |
| { |
| VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev); |
| |
| unregister_savevm(vrng->qdev, "virtio-rng", vrng); |
| virtio_cleanup(vdev); |
| } |