[PATCH V12 4/6] mdev: introduce mediated virtio bus

[Jason Wang <jasowang@redhat.com>]

This patch implements a mediated virtio bus over mdev framework. This
will be used by the future virtio-mdev and vhost-mdev on top to allow
driver from either userspace or kernel to control the device which is
capable of offloading virtio datapath.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 MAINTAINERS                       |   2 +
 drivers/mdev/Kconfig              |  10 ++
 drivers/mdev/Makefile             |   2 +
 drivers/mdev/virtio.c             | 126 +++++++++++++++++++++++
 include/linux/mdev_virtio.h       | 163 ++++++++++++++++++++++++++++++
 include/linux/mod_devicetable.h   |   8 ++
 scripts/mod/devicetable-offsets.c |   3 +
 scripts/mod/file2alias.c          |  12 +++
 8 files changed, 326 insertions(+)
 create mode 100644 drivers/mdev/virtio.c
 create mode 100644 include/linux/mdev_virtio.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 829428d8a9f5..4c2e41641f7a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17251,6 +17251,8 @@ F:	include/linux/virtio*.h
 F:	include/uapi/linux/virtio_*.h
 F:	drivers/crypto/virtio/
 F:	mm/balloon_compaction.c
+F:	include/linux/mdev_virtio.h
+F:	drivers/mdev/virtio.c
 
 VIRTIO BLOCK AND SCSI DRIVERS
 M:	"Michael S. Tsirkin" <mst@redhat.com>
diff --git a/drivers/mdev/Kconfig b/drivers/mdev/Kconfig
index 4561f2d4178f..cd84d4670552 100644
--- a/drivers/mdev/Kconfig
+++ b/drivers/mdev/Kconfig
@@ -17,3 +17,13 @@ config VFIO_MDEV
 	  more details.
 
 	  If you don't know what do here, say N.
+
+config MDEV_VIRTIO
+       tristate "Mediated VIRTIO bus"
+       depends on VIRTIO && MDEV
+       default n
+       help
+	  Proivdes a mediated BUS for virtio. It could be used by
+          either kenrel driver or userspace driver.
+
+	  If you don't know what do here, say N.
diff --git a/drivers/mdev/Makefile b/drivers/mdev/Makefile
index 0b749e7f8ff4..eb14031c9944 100644
--- a/drivers/mdev/Makefile
+++ b/drivers/mdev/Makefile
@@ -1,5 +1,7 @@
 
 mdev-y := mdev_core.o mdev_sysfs.o mdev_driver.o
 mdev_vfio-y := vfio.o
+mdev_virtio-y := virtio.o
 obj-$(CONFIG_MDEV) += mdev.o
 obj-$(CONFIG_VFIO_MDEV) += mdev_vfio.o
+obj-$(CONFIG_MDEV_VIRTIO) += mdev_virtio.o
diff --git a/drivers/mdev/virtio.c b/drivers/mdev/virtio.c
new file mode 100644
index 000000000000..25de329615c4
--- /dev/null
+++ b/drivers/mdev/virtio.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Mediated VIRTIO bus
+ *
+ * Copyright (c) 2019, Red Hat. All rights reserved.
+ *     Author: Jason Wang <jasowang@redhat.com>
+ */
+
+#include <linux/module.h>
+#include <linux/uuid.h>
+#include <linux/device.h>
+#include <linux/mdev.h>
+#include <linux/mdev_virtio.h>
+#include <linux/mod_devicetable.h>
+
+#include "mdev_private.h"
+
+#define DRIVER_VERSION		"0.1"
+#define DRIVER_AUTHOR		"Jason Wang"
+#define DRIVER_DESC		"Mediated VIRTIO bus"
+
+struct bus_type mdev_virtio_bus_type;
+
+struct mdev_virtio_device {
+	struct mdev_device mdev;
+	const struct mdev_virtio_ops *ops;
+	u16 class_id;
+};
+
+#define to_mdev_virtio(mdev) container_of(mdev, \
+					  struct mdev_virtio_device, mdev)
+#define to_mdev_virtio_drv(mdrv) container_of(mdrv, \
+					      struct mdev_virtio_driver, drv)
+
+static int mdev_virtio_match(struct device *dev, struct device_driver *drv)
+{
+	unsigned int i;
+	struct mdev_device *mdev = mdev_from_dev(dev, &mdev_virtio_bus_type);
+	struct mdev_virtio_device *mdev_virtio = to_mdev_virtio(mdev);
+	struct mdev_driver *mdrv = to_mdev_driver(drv);
+	struct mdev_virtio_driver *mdrv_virtio = to_mdev_virtio_drv(mdrv);
+	const struct mdev_virtio_class_id *ids = mdrv_virtio->id_table;
+
+	if (!ids)
+		return 0;
+
+	for (i = 0; ids[i].id; i++)
+		if (ids[i].id == mdev_virtio->class_id)
+			return 1;
+	return 0;
+}
+
+static int mdev_virtio_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct mdev_device *mdev = mdev_from_dev(dev, &mdev_virtio_bus_type);
+	struct mdev_virtio_device *mdev_virtio = to_mdev_virtio(mdev);
+
+	return add_uevent_var(env, "MODALIAS=mdev_virtio:c%02X",
+			      mdev_virtio->class_id);
+}
+
+struct bus_type mdev_virtio_bus_type = {
+	.name		= "mdev_virtio",
+	.probe		= mdev_probe,
+	.remove		= mdev_remove,
+	.match	        = mdev_virtio_match,
+	.uevent		= mdev_virtio_uevent,
+};
+EXPORT_SYMBOL(mdev_virtio_bus_type);
+
+void mdev_virtio_set_class_id(struct mdev_device *mdev, u16 class_id)
+{
+	struct mdev_virtio_device *mdev_virtio = to_mdev_virtio(mdev);
+
+	mdev_virtio->class_id = class_id;
+}
+EXPORT_SYMBOL(mdev_virtio_set_class_id);
+
+int mdev_virtio_register_device(struct device *dev,
+				const struct mdev_parent_ops *ops)
+{
+	return mdev_register_device(dev, ops, &mdev_virtio_bus_type,
+				    sizeof(struct mdev_virtio_device));
+}
+EXPORT_SYMBOL(mdev_virtio_register_device);
+
+void mdev_virtio_unregister_device(struct device *dev)
+{
+	return mdev_unregister_device(dev);
+}
+EXPORT_SYMBOL(mdev_virtio_unregister_device);
+
+void mdev_virtio_set_ops(struct mdev_device *mdev,
+			 const struct mdev_virtio_ops *ops)
+{
+	struct mdev_virtio_device *mdev_virtio = to_mdev_virtio(mdev);
+
+	mdev_virtio->ops = ops;
+}
+EXPORT_SYMBOL(mdev_virtio_set_ops);
+
+const struct mdev_virtio_ops *mdev_virtio_get_ops(struct mdev_device *mdev)
+{
+	struct mdev_virtio_device *mdev_virtio = to_mdev_virtio(mdev);
+
+	return mdev_virtio->ops;
+}
+EXPORT_SYMBOL(mdev_virtio_get_ops);
+
+static int __init mdev_init(void)
+{
+	return mdev_register_bus(&mdev_virtio_bus_type);
+}
+
+static void __exit mdev_exit(void)
+{
+	mdev_unregister_bus(&mdev_virtio_bus_type);
+}
+
+module_init(mdev_init)
+module_exit(mdev_exit)
+
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
diff --git a/include/linux/mdev_virtio.h b/include/linux/mdev_virtio.h
new file mode 100644
index 000000000000..ef2dbb6c383a
--- /dev/null
+++ b/include/linux/mdev_virtio.h
@@ -0,0 +1,163 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * VIRTIO Mediated device definition
+ *
+ * Copyright (c) 2019, Red Hat. All rights reserved.
+ *     Author: Jason Wang <jasowang@redhat.com>
+ */
+
+#ifndef VIRTIO_MDEV_H
+#define VIRTIO_MDEV_H
+
+#include <linux/interrupt.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mdev.h>
+
+extern struct bus_type mdev_virtio_bus_type;
+
+struct mdev_virtio_driver {
+	struct mdev_driver drv;
+	const struct mdev_virtio_class_id *id_table;
+};
+
+struct virtio_mdev_callback {
+	irqreturn_t (*callback)(void *data);
+	void *private;
+};
+
+/**
+ * struct mdev_virtio_device_ops - Structure to be registered for each
+ * mdev device to register the device for virtio/vhost drivers.
+ *
+ * The callbacks are mandatory unless explicitly mentioned.
+ *
+ * @set_vq_address:		Set the address of virtqueue
+ *				@mdev: mediated device
+ *				@idx: virtqueue index
+ *				@desc_area: address of desc area
+ *				@driver_area: address of driver area
+ *				@device_area: address of device area
+ *				Returns integer: success (0) or error (< 0)
+ * @set_vq_num:			Set the size of virtqueue
+ *				@mdev: mediated device
+ *				@idx: virtqueue index
+ *				@num: the size of virtqueue
+ * @kick_vq:			Kick the virtqueue
+ *				@mdev: mediated device
+ *				@idx: virtqueue index
+ * @set_vq_cb:			Set the interrupt callback function for
+ *				a virtqueue
+ *				@mdev: mediated device
+ *				@idx: virtqueue index
+ *				@cb: virtio-mdev interrupt callback structure
+ * @set_vq_ready:		Set ready status for a virtqueue
+ *				@mdev: mediated device
+ *				@idx: virtqueue index
+ *				@ready: ready (true) not ready(false)
+ * @get_vq_ready:		Get ready status for a virtqueue
+ *				@mdev: mediated device
+ *				@idx: virtqueue index
+ *				Returns boolean: ready (true) or not (false)
+ * @set_vq_state:		Set the state for a virtqueue
+ *				@mdev: mediated device
+ *				@idx: virtqueue index
+ *				@state: virtqueue state (last_avail_idx)
+ *				Returns integer: success (0) or error (< 0)
+ * @get_vq_state:		Get the state for a virtqueue
+ *				@mdev: mediated device
+ *				@idx: virtqueue index
+ *				Returns virtqueue state (last_avail_idx)
+ * @get_vq_align:		Get the virtqueue align requirement
+ *				for the device
+ *				@mdev: mediated device
+ *				Returns virtqueue algin requirement
+ * @get_features:		Get virtio features supported by the device
+ *				@mdev: mediated device
+ *				Returns the virtio features support by the
+ *				device
+ * @set_features:		Set virtio features supported by the driver
+ *				@mdev: mediated device
+ *				@features: feature support by the driver
+ *				Returns integer: success (0) or error (< 0)
+ * @set_config_cb:		Set the config interrupt callback
+ *				@mdev: mediated device
+ *				@cb: virtio-mdev interrupt callback structure
+ * @get_vq_num_max:		Get the max size of virtqueue
+ *				@mdev: mediated device
+ *				Returns u16: max size of virtqueue
+ * @get_device_id:		Get virtio device id
+ *				@mdev: mediated device
+ *				Returns u32: virtio device id
+ * @get_vendor_id:		Get id for the vendor that provides this device
+ *				@mdev: mediated device
+ *				Returns u32: virtio vendor id
+ * @get_status:			Get the device status
+ *				@mdev: mediated device
+ *				Returns u8: virtio device status
+ * @set_status:			Set the device status
+ *				@mdev: mediated device
+ *				@status: virtio device status
+ * @get_config:			Read from device specific configuration space
+ *				@mdev: mediated device
+ *				@offset: offset from the beginning of
+ *				configuration space
+ *				@buf: buffer used to read to
+ *				@len: the length to read from
+ *				configration space
+ * @set_config:			Write to device specific configuration space
+ *				@mdev: mediated device
+ *				@offset: offset from the beginning of
+ *				configuration space
+ *				@buf: buffer used to write from
+ *				@len: the length to write to
+ *				configration space
+ * @get_generation:		Get device config generaton (optional)
+ *				@mdev: mediated device
+ *				Returns u32: device generation
+ */
+struct mdev_virtio_ops {
+	/* Virtqueue ops */
+	int (*set_vq_address)(struct mdev_device *mdev,
+			      u16 idx, u64 desc_area, u64 driver_area,
+			      u64 device_area);
+	void (*set_vq_num)(struct mdev_device *mdev, u16 idx, u32 num);
+	void (*kick_vq)(struct mdev_device *mdev, u16 idx);
+	void (*set_vq_cb)(struct mdev_device *mdev, u16 idx,
+			  struct virtio_mdev_callback *cb);
+	void (*set_vq_ready)(struct mdev_device *mdev, u16 idx, bool ready);
+	bool (*get_vq_ready)(struct mdev_device *mdev, u16 idx);
+	int (*set_vq_state)(struct mdev_device *mdev, u16 idx, u64 state);
+	u64 (*get_vq_state)(struct mdev_device *mdev, u16 idx);
+
+	/* Device ops */
+	u16 (*get_vq_align)(struct mdev_device *mdev);
+	u64 (*get_features)(struct mdev_device *mdev);
+	int (*set_features)(struct mdev_device *mdev, u64 features);
+	void (*set_config_cb)(struct mdev_device *mdev,
+			      struct virtio_mdev_callback *cb);
+	u16 (*get_vq_num_max)(struct mdev_device *mdev);
+	u32 (*get_device_id)(struct mdev_device *mdev);
+	u32 (*get_vendor_id)(struct mdev_device *mdev);
+	u8 (*get_status)(struct mdev_device *mdev);
+	void (*set_status)(struct mdev_device *mdev, u8 status);
+	void (*get_config)(struct mdev_device *mdev, unsigned int offset,
+			   void *buf, unsigned int len);
+	void (*set_config)(struct mdev_device *mdev, unsigned int offset,
+			   const void *buf, unsigned int len);
+	u32 (*get_generation)(struct mdev_device *mdev);
+};
+
+int mdev_virtio_register_device(struct device *dev,
+				const struct mdev_parent_ops *ops);
+void mdev_virtio_unregister_device(struct device *dev);
+void mdev_virtio_set_ops(struct mdev_device *mdev,
+			 const struct mdev_virtio_ops *ops);
+const struct mdev_virtio_ops *mdev_virtio_get_ops(struct mdev_device *mdev);
+void mdev_virtio_set_class_id(struct mdev_device *mdev, u16 class_id);
+
+static inline struct mdev_device *mdev_virtio_from_dev(struct device *dev)
+{
+	return mdev_from_dev(dev, &mdev_virtio_bus_type);
+}
+
+#endif
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 5714fd35a83c..59006c47ae8e 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -821,4 +821,12 @@ struct wmi_device_id {
 	const void *context;
 };
 
+/**
+ * struct mdev_class_id - MDEV VIRTIO device class identifier
+ * @id: Used to identify a specific class of device, e.g vfio-mdev device.
+ */
+struct mdev_virtio_class_id {
+	__u16 id;
+};
+
 #endif /* LINUX_MOD_DEVICETABLE_H */
diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index 054405b90ba4..178fd7c70812 100644
--- a/scripts/mod/devicetable-offsets.c
+++ b/scripts/mod/devicetable-offsets.c
@@ -231,5 +231,8 @@ int main(void)
 	DEVID(wmi_device_id);
 	DEVID_FIELD(wmi_device_id, guid_string);
 
+	DEVID(mdev_virtio_class_id);
+	DEVID_FIELD(mdev_virtio_class_id, id);
+
 	return 0;
 }
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index c91eba751804..1a9c1f591951 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -1335,6 +1335,17 @@ static int do_wmi_entry(const char *filename, void *symval, char *alias)
 	return 1;
 }
 
+/* looks like: "mdev_virtio:cN" */
+static int do_mdev_virtio_entry(const char *filename, void *symval, char *alias)
+{
+	DEF_FIELD(symval, mdev_virtio_class_id, id);
+
+	sprintf(alias, "mdev_virtio:c%02X", id);
+	add_wildcard(alias);
+	return 1;
+}
+
+
 /* Does namelen bytes of name exactly match the symbol? */
 static bool sym_is(const char *name, unsigned namelen, const char *symbol)
 {
@@ -1407,6 +1418,7 @@ static const struct devtable devtable[] = {
 	{"typec", SIZE_typec_device_id, do_typec_entry},
 	{"tee", SIZE_tee_client_device_id, do_tee_entry},
 	{"wmi", SIZE_wmi_device_id, do_wmi_entry},
+	{"mdev_virtio", SIZE_mdev_virtio_class_id, do_mdev_virtio_entry},
 };
 
 /* Create MODULE_ALIAS() statements.
-- 
2.19.1