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);
+}