drivers/vhost-rng: add vhost rng driver support for NuttX

vhost-rng is a simple virtio device implementation, it receives
the buffer receviced from the virtio-rng driver and fill the random
number to this buffer and return to virtio-rng.

Signed-off-by: Bowen Wang <wangbowen6@xiaomi.com>

drivers/vhost/CMakeLists.txt

@@ -23,5 +23,9 @@ if(CONFIG_DRIVERS_VHOST)
   list(APPEND SRCS vhost.c)
 endif()
 
+if(CONFIG_DRIVERS_VHOST_RNG)
+  list(APPEND SRCS vhost_rng.c)
+endif()
+
 target_sources(drivers PRIVATE ${SRCS})
 target_include_directories(drivers PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})

drivers/vhost/Kconfig

@@ -10,4 +10,8 @@ menuconfig DRIVERS_VHOST
 
 if DRIVERS_VHOST
 
+config DRIVERS_VHOST_RNG
+	bool "Virtual Host Rng Device Support"
+	default n
+
 endif # DRIVERS_VHOST

drivers/vhost/Make.defs

@@ -24,6 +24,10 @@ ifeq ($(CONFIG_DRIVERS_VHOST),y)
   CSRCS += vhost.c
 endif
 
+ifeq ($(CONFIG_DRIVERS_VHOST_RNG),y)
+  CSRCS += vhost-rng.c
+endif
+
 # Include build support
 
 DEPPATH += --dep-path vhost

drivers/vhost/vhost-rng.c

@@ -0,0 +1,189 @@
+/****************************************************************************
+ * drivers/vhost/vhost-rng.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <debug.h>
+#include <errno.h>
+#include <stdio.h>
+#include <sys/random.h>
+
+#include <nuttx/kmalloc.h>
+#include <nuttx/vhost/vhost.h>
+#include <nuttx/wqueue.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+struct vhost_rng_priv_s
+{
+  FAR struct vhost_device *hdev;
+  struct work_s            work;
+};
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/* Vhost driver functions */
+
+static int vhost_rng_probe(FAR struct vhost_device *hdev);
+static void vhost_rng_remove(FAR struct vhost_device *hdev);
+
+static void vhost_rng_work(FAR void *arg);
+static void vhost_rng_handler(FAR struct virtqueue *vq);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static struct vhost_driver g_vhost_rng_driver =
+{
+  LIST_INITIAL_VALUE(g_vhost_rng_driver.node), /* Node */
+  VIRTIO_ID_ENTROPY,                           /* Device id */
+  vhost_rng_probe,                             /* Probe */
+  vhost_rng_remove,                            /* Remove */
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: vhost_rng_thread
+ ****************************************************************************/
+
+static void vhost_rng_work(FAR void *arg)
+{
+  FAR struct vhost_rng_priv_s *priv = arg;
+  FAR struct virtqueue *vq;
+  FAR void *buf;
+  uint16_t idx;
+  uint32_t len;
+  ssize_t ret;
+
+  vq = priv->hdev->vrings_info[0].vq;
+  for (; ; )
+    {
+      buf = virtqueue_get_available_buffer(vq, &idx, &len);
+      if (buf == NULL)
+        {
+          break;
+        }
+
+      ret = getrandom(buf, len, 0);
+      if (ret < 0)
+        {
+          vhosterr("getrandom failed, ret=%zd\n", ret);
+          ret = 0;
+        }
+
+      virtqueue_add_consumed_buffer(vq, idx, (uint32_t)ret);
+      virtqueue_kick(vq);
+    }
+}
+
+/****************************************************************************
+ * Name: vhost_rng_handler
+ ****************************************************************************/
+
+static void vhost_rng_handler(FAR struct virtqueue *vq)
+{
+  FAR struct vhost_rng_priv_s *priv = vq->vq_dev->priv;
+
+  if (work_available(&priv->work))
+    {
+      work_queue(HPWORK, &priv->work, vhost_rng_work, priv, 0);
+    }
+}
+
+/****************************************************************************
+ * Name: vhost_rng_probe
+ ****************************************************************************/
+
+static int vhost_rng_probe(FAR struct vhost_device *hdev)
+{
+  FAR struct vhost_rng_priv_s *priv;
+  FAR const char *vqnames[1];
+  vq_callback callback[1];
+  int ret;
+
+  priv = kmm_zalloc(sizeof(*priv));
+  if (priv == NULL)
+    {
+      vhosterr("No enough memory\n");
+      return -ENOMEM;
+    }
+
+  priv->hdev = hdev;
+  hdev->priv = priv;
+
+  /* Create the virtqueues */
+
+  vqnames[0]  = "virtio_rng";
+  callback[0] = vhost_rng_handler;
+  ret = vhost_create_virtqueues(hdev, 0, 1, vqnames, callback);
+  if (ret < 0)
+    {
+      vhosterr("virtio_device_create_virtqueue failed, ret=%d\n", ret);
+      goto err;
+    }
+
+  virtqueue_enable_cb(hdev->vrings_info[0].vq);
+  return ret;
+
+err:
+  kmm_free(priv);
+  return ret;
+}
+
+/****************************************************************************
+ * Name: vhost_rng_remove
+ ****************************************************************************/
+
+static void vhost_rng_remove(FAR struct vhost_device *hdev)
+{
+  FAR struct vhost_rng_priv_s *priv = hdev->priv;
+
+  virtqueue_disable_cb(hdev->vrings_info[0].vq);
+  work_cancel_sync(HPWORK, &priv->work);
+  vhost_delete_virtqueues(hdev);
+  kmm_free(priv);
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: vhost_register_rng_driver
+ ****************************************************************************/
+
+int vhost_register_rng_driver(void)
+{
+  return vhost_register_driver(&g_vhost_rng_driver);
+}

drivers/vhost/vhost-rng.h

@@ -0,0 +1,61 @@
+/****************************************************************************
+ * drivers/vhost/vhost-rng.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __DRIVERS_VHOST_VHOST_RNG_H
+#define __DRIVERS_VHOST_VHOST_RNG_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#ifdef CONFIG_DRIVERS_VHOST_RNG
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+int vhost_register_rng_driver(void);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CONFIG_DRIVERS_VHOST_RNG */
+
+#endif /* __DRIVERS_VHOST_VHOST_RNG_H */

drivers/vhost/vhost.c

@@ -29,6 +29,8 @@
 #include <nuttx/wqueue.h>
 #include <nuttx/vhost/vhost.h>
 
+#include "vhost-rng.h"
+
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
@@ -375,4 +377,15 @@ out:
 
 void vhost_register_drivers(void)
 {
+  int ret;
+
+#ifdef CONFIG_DRIVERS_VHOST_RNG
+  ret = vhost_register_rng_driver();
+  if (ret < 0)
+    {
+      vrterr("vhost_register_rng_driver failed, ret=%d\n", ret);
+    }
+#endif
+
+  UNUSED(ret);
 }