diff options
Diffstat (limited to 'hw/virtio-rng.c')
| -rw-r--r-- | hw/virtio-rng.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/hw/virtio-rng.c b/hw/virtio-rng.c new file mode 100644 index 0000000000..b7fb5e9d61 --- /dev/null +++ b/hw/virtio-rng.c @@ -0,0 +1,211 @@ +/* + * 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; +} 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; +} + +/* 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; + } + + 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. + */ + len = pop_an_elem(vrng); + if (len) { + 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); + size_t size; + + size = pop_an_elem(vrng); + if (size) { + rng_backend_request_entropy(vrng->rng, size, chr_read, 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); + } + return 0; +} + +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; + 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); +} |