[Qemu-devel] [PATCH v14 02/22] vfio: VFIO based driver for Mediated devices

[Kirti Wankhede]

vfio_mdev driver registers with mdev core driver.
mdev core driver creates mediated device and calls probe routine of
vfio_mdev driver for each device.
Probe routine of vfio_mdev driver adds mediated device to VFIO core module

This driver forms a shim layer that pass through VFIO devices operations
to vendor driver for mediated devices.

Signed-off-by: Kirti Wankhede <address@hidden>
Signed-off-by: Neo Jia <address@hidden>
Reviewed-by: Jike Song <address@hidden>
Reviewed-by: Dong Jia Shi <address@hidden>

Change-Id: I583f4734752971d3d112324d69e2508c88f359ec
---
 drivers/vfio/mdev/Kconfig     |   7 ++
 drivers/vfio/mdev/Makefile    |   1 +
 drivers/vfio/mdev/mdev_core.c |  13 +++-
 drivers/vfio/mdev/vfio_mdev.c | 148 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 168 insertions(+), 1 deletion(-)
 create mode 100644 drivers/vfio/mdev/vfio_mdev.c

diff --git a/drivers/vfio/mdev/Kconfig b/drivers/vfio/mdev/Kconfig
index 258481d65ebd..424ddebee55d 100644
--- a/drivers/vfio/mdev/Kconfig
+++ b/drivers/vfio/mdev/Kconfig
@@ -7,3 +7,10 @@ config VFIO_MDEV
          Provides a framework to virtualize devices.
 
          If you don't know what do here, say N.
+
+config VFIO_MDEV_DEVICE
+       tristate "VFIO driver for Mediated devices"
+       depends on VFIO && VFIO_MDEV
+       default n
+       help
+         VFIO based driver for Mediated devices.
diff --git a/drivers/vfio/mdev/Makefile b/drivers/vfio/mdev/Makefile
index 31bc04801d94..fa2d5ea466ee 100644
--- a/drivers/vfio/mdev/Makefile
+++ b/drivers/vfio/mdev/Makefile
@@ -2,3 +2,4 @@
 mdev-y := mdev_core.o mdev_sysfs.o mdev_driver.o
 
 obj-$(CONFIG_VFIO_MDEV) += mdev.o
+obj-$(CONFIG_VFIO_MDEV_DEVICE) += vfio_mdev.o
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 613e8a8a3b2a..be1ee89ee917 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -354,7 +354,18 @@ int mdev_device_remove(struct device *dev, bool 
force_remove)
 
 static int __init mdev_init(void)
 {
-       return mdev_bus_register();
+       int ret;
+
+       ret = mdev_bus_register();
+
+       /*
+        * Attempt to load known vfio_mdev.  This gives us a working environment
+        * without the user needing to explicitly load vfio_mdev driver.
+        */
+       if (!ret)
+               request_module_nowait("vfio_mdev");
+
+       return ret;
 }
 
 static void __exit mdev_exit(void)
diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
new file mode 100644
index 000000000000..ffc36758cb84
--- /dev/null
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -0,0 +1,148 @@
+/*
+ * VFIO based driver for Mediated device
+ *
+ * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
+ *     Author: Neo Jia <address@hidden>
+ *             Kirti Wankhede <address@hidden>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/vfio.h>
+#include <linux/mdev.h>
+
+#include "mdev_private.h"
+
+#define DRIVER_VERSION  "0.1"
+#define DRIVER_AUTHOR   "NVIDIA Corporation"
+#define DRIVER_DESC     "VFIO based driver for Mediated device"
+
+static int vfio_mdev_open(void *device_data)
+{
+       struct mdev_device *mdev = device_data;
+       struct parent_device *parent = mdev->parent;
+       int ret;
+
+       if (unlikely(!parent->ops->open))
+               return -EINVAL;
+
+       if (!try_module_get(THIS_MODULE))
+               return -ENODEV;
+
+       ret = parent->ops->open(mdev);
+       if (ret)
+               module_put(THIS_MODULE);
+
+       return ret;
+}
+
+static void vfio_mdev_release(void *device_data)
+{
+       struct mdev_device *mdev = device_data;
+       struct parent_device *parent = mdev->parent;
+
+       if (likely(parent->ops->release))
+               parent->ops->release(mdev);
+
+       module_put(THIS_MODULE);
+}
+
+static long vfio_mdev_unlocked_ioctl(void *device_data,
+                                    unsigned int cmd, unsigned long arg)
+{
+       struct mdev_device *mdev = device_data;
+       struct parent_device *parent = mdev->parent;
+
+       if (unlikely(!parent->ops->ioctl))
+               return -EINVAL;
+
+       return parent->ops->ioctl(mdev, cmd, arg);
+}
+
+static ssize_t vfio_mdev_read(void *device_data, char __user *buf,
+                             size_t count, loff_t *ppos)
+{
+       struct mdev_device *mdev = device_data;
+       struct parent_device *parent = mdev->parent;
+
+       if (unlikely(!parent->ops->read))
+               return -EINVAL;
+
+       return parent->ops->read(mdev, buf, count, ppos);
+}
+
+static ssize_t vfio_mdev_write(void *device_data, const char __user *buf,
+                              size_t count, loff_t *ppos)
+{
+       struct mdev_device *mdev = device_data;
+       struct parent_device *parent = mdev->parent;
+
+       if (unlikely(!parent->ops->write))
+               return -EINVAL;
+
+       return parent->ops->write(mdev, buf, count, ppos);
+}
+
+static int vfio_mdev_mmap(void *device_data, struct vm_area_struct *vma)
+{
+       struct mdev_device *mdev = device_data;
+       struct parent_device *parent = mdev->parent;
+
+       if (unlikely(!parent->ops->mmap))
+               return -EINVAL;
+
+       return parent->ops->mmap(mdev, vma);
+}
+
+static const struct vfio_device_ops vfio_mdev_dev_ops = {
+       .name           = "vfio-mdev",
+       .open           = vfio_mdev_open,
+       .release        = vfio_mdev_release,
+       .ioctl          = vfio_mdev_unlocked_ioctl,
+       .read           = vfio_mdev_read,
+       .write          = vfio_mdev_write,
+       .mmap           = vfio_mdev_mmap,
+};
+
+int vfio_mdev_probe(struct device *dev)
+{
+       struct mdev_device *mdev = to_mdev_device(dev);
+
+       return vfio_add_group_dev(dev, &vfio_mdev_dev_ops, mdev);
+}
+
+void vfio_mdev_remove(struct device *dev)
+{
+       vfio_del_group_dev(dev);
+}
+
+struct mdev_driver vfio_mdev_driver = {
+       .name   = "vfio_mdev",
+       .probe  = vfio_mdev_probe,
+       .remove = vfio_mdev_remove,
+};
+
+static int __init vfio_mdev_init(void)
+{
+       return mdev_register_driver(&vfio_mdev_driver, THIS_MODULE);
+}
+
+static void __exit vfio_mdev_exit(void)
+{
+       mdev_unregister_driver(&vfio_mdev_driver);
+}
+
+module_init(vfio_mdev_init)
+module_exit(vfio_mdev_exit)
+
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
-- 
2.7.0