1 files changed, 179 insertions, 0 deletions
diff --git a/virtio_rng.c b/virtio_rng.c
new file mode 100644
index 0000000..6a5b24b
--- /dev/null
+++ b/virtio_rng.c
@@ -0,0 +1,179 @@
+/*
+ * A virtio device implementing a hardware random number generator.
+ *
+ * Based on virtio-rng.c of QEMU project
+ *  Copyright 2012 Red Hat, Inc.
+ *  Copyright 2012 Amit Shah <amit.shah@redhat.com>
+ *
+ * Copyright 2022-2023 Virtual Open Systems SAS.
+ *
+ * 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 <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdbool.h>
+#include <sys/param.h>
+
+/* Project header files */
+#include "virtio_loopback.h"
+#include "virtio_rng.h"
+
+#ifdef DEBUG
+#define DBG(...) printf("virtio-rng: " __VA_ARGS__)
+#else
+#define DBG(...)
+#endif /* DEBUG */
+
+bool is_guest_ready(VirtIORNG *vrng)
+{
+    VirtIODevice *vdev = vrng->parent_obj;
+
+    if (virtio_queue_ready(vrng->vq)
+        && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
+        return true;
+    }
+    return false;
+}
+
+size_t get_request_size(VirtQueue *vq, unsigned quota)
+{
+    unsigned int in, out;
+
+    virtqueue_get_avail_bytes(vq, &in, &out, quota, 0);
+    return in;
+}
+
+void virtio_rng_set_status(VirtIODevice *vdev, uint8_t status)
+{
+    VirtIORNG *vrng = vdev->vrng;
+
+    vdev->status = status;
+
+    /* Something changed, try to process buffers */
+    virtio_rng_process(vrng);
+}
+
+/* Send data from a char device over to the guest */
+void chr_read(VirtIORNG *vrng, const void *buf, size_t size)
+{
+    VirtIODevice *vdev = vrng->parent_obj;
+    VirtQueueElement *elem;
+    size_t len;
+    int offset;
+
+    if (!is_guest_ready(vrng)) {
+        return;
+    }
+
+    vrng->quota_remaining -= size;
+
+    offset = 0;
+    while (offset < size) {
+        elem = virtqueue_pop(vrng->vq, sizeof(VirtQueueElement));
+
+
+        if (!elem) {
+            break;
+        }
+        len = qemu_iov_from_buf(elem->in_sg, elem->in_num,
+                           0, buf + offset, size - offset);
+        offset += len;
+
+        virtqueue_push(vrng->vq, elem, len);
+
+        /*
+         * TODO: We need tp free the elem
+         *
+         * 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);
+    }
+}
+
+const char test_str[64] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
+                           10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
+                           20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
+                           30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
+                           40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
+                           50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
+                           60, 61, 62, 63};
+
+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) {
+        chr_read(vrng, &test_str, size);
+    }
+}
+
+void handle_input(VirtIODevice *vdev, VirtQueue *vq)
+{
+    virtio_rng_process(vdev->vrng);
+}
+
+static void virtio_dev_class_init(VirtIODevice *vdev)
+{
+    vdev->vdev_class = (VirtioDeviceClass *)malloc(sizeof(VirtioDeviceClass));
+    vdev->vdev_class->parent = vdev;
+    vdev->vdev_class->set_status = virtio_rng_set_status;
+}
+
+void virtio_rng_init(VirtIODevice *vdev)
+{
+    VirtIORNG *vrng = (VirtIORNG *)malloc(sizeof(VirtIORNG));
+    vdev->vrng = vrng;
+    vrng->parent_obj = vdev;
+    vrng->vq = vdev->vq;
+    vrng->quota_remaining = LONG_MAX;
+
+    /* Prepare dev_class */
+    virtio_dev_class_init(vdev);
+}
+
+
+void virtio_rng_realize(void)
+{
+    /* prepare procy and virtio dev*/
+    proxy = (VirtIOMMIOProxy *)malloc(sizeof(VirtIOMMIOProxy));
+
+    virtio_dev_init(global_vdev, "virtio-rng", 4, 0);
+
+    virtio_rng_init(global_vdev);
+
+    global_vdev->vq = virtio_add_queue(global_vdev, 8, handle_input);
+
+    global_vdev->host_features = 0x39000000;
+
+    *proxy = (VirtIOMMIOProxy) {
+        .legacy = 1,
+    };
+}
+