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-rw-r--r--hw/virtio/virtio-rng.c187
1 files changed, 187 insertions, 0 deletions
diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
new file mode 100644
index 0000000000..6079b2a3a9
--- /dev/null
+++ b/hw/virtio/virtio-rng.c
@@ -0,0 +1,187 @@
+/*
+ * 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/iov.h"
+#include "hw/qdev.h"
+#include "qapi/qmp/qerror.h"
+#include "hw/virtio/virtio.h"
+#include "hw/virtio/virtio-rng.h"
+#include "qemu/rng.h"
+
+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 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;
+ VirtQueueElement elem;
+ size_t len;
+ int offset;
+
+ if (!is_guest_ready(vrng)) {
+ return;
+ }
+
+ vrng->quota_remaining -= size;
+
+ offset = 0;
+ while (offset < size) {
+ if (!virtqueue_pop(vrng->vq, &elem)) {
+ break;
+ }
+ len = iov_from_buf(elem.in_sg, elem.in_num,
+ 0, buf + offset, size - offset);
+ offset += len;
+
+ virtqueue_push(vrng->vq, &elem, len);
+ }
+ virtio_notify(&vrng->vdev, vrng->vq);
+}
+
+static void virtio_rng_process(VirtIORNG *vrng)
+{
+ size_t size;
+ unsigned quota;
+
+ if (!is_guest_ready(vrng)) {
+ return;
+ }
+
+ 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);
+ 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 = 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);
+}
+
+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);
+
+ /* 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;
+
+ assert(vrng->conf->max_bytes <= INT64_MAX);
+ vrng->quota_remaining = vrng->conf->max_bytes;
+
+ 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);
+
+ qemu_del_timer(vrng->rate_limit_timer);
+ qemu_free_timer(vrng->rate_limit_timer);
+ unregister_savevm(vrng->qdev, "virtio-rng", vrng);
+ virtio_cleanup(vdev);
+}