[PATCH V5 0/6] mdev based hardware virtio offloading support

[PATCH V5 0/6] mdev based hardware virtio offloading support

[Jason Wang]

Hi all:

There are hardwares that can do virtio datapath offloading while
having its own control path. This path tries to implement a mdev based
unified API to support using kernel virtio driver to drive those
devices. This is done by introducing a new mdev transport for virtio
(virtio_mdev) and register itself as a new kind of mdev driver. Then
it provides a unified way for kernel virtio driver to talk with mdev
device implementation.

Though the series only contains kernel driver support, the goal is to
make the transport generic enough to support userspace drivers. This
means vhost-mdev[1] could be built on top as well by resuing the
transport.

A sample driver is also implemented which simulate a virito-net
loopback ethernet device on top of vringh + workqueue. This could be
used as a reference implementation for real hardware driver.

Also a real ICF VF driver was also posted here[2] which is a good
reference for vendors who is interested in their own virtio datapath
offloading product.

Consider mdev framework only support VFIO device and driver right now,
this series also extend it to support other types. This is done
through introducing class id to the device and pairing it with
id_talbe claimed by the driver. On top, this seris also decouple
device specific parents ops out of the common ones.

Pktgen test was done with virito-net + mvnet loop back device.

Please review.

[1] https://lkml.org/lkml/2019/10/22/262
[2] https://lkml.org/lkml/2019/10/15/1226

Changes from V4:

- keep mdev_set_class() for the device that doesn't use device ops
- use union for device ops pointer in mdev_device
- introduce class specific helper for getting is device ops
- use WARN_ON instead of BUG_ON in mdev_set_virtio_ops
- explain details of get_mdev_features() and get_vendor_id()
- distinguish the optional virito device ops from mandatory ones and
  make get_generation() optional
- rename vfio_mdev.h to vfio_mdev_ops.h, rename virito_mdev.h to
  virtio_mdev_ops.h
- don't abuse version fileds in virtio_mdev structure, use features
  instead
- fix warning during device remove
- style & docs tweaks and typo fixes

Changes from V3:

- document that class id (device ops) must be specified in create()
- add WARN() when trying to set class_id when it has already set
- add WARN() when class_id is not specified in create() and correctly
  return an error in this case
- correct the prototype of mdev_set_class() in the doc
- add documention of mdev_set_class()
- remove the unnecessary "class_id_fail" label when class id is not
  specified in create()
- convert id_table in vfio_mdev to const
- move mdev_set_class and its friends after mdev_uuid()
- suqash the patch of bus uevent into patch of introducing class id
- tweak the words in the docs per Cornelia suggestion
- tie class_id and device ops through class specific initialization
  routine like mdev_set_vfio_ops()
- typos fixes in the docs of virtio-mdev callbacks
- document the usage of virtqueues in struct virtio_mdev_device
- remove the useless vqs array in struct virtio_mdev_device
- rename MDEV_ID_XXX to MDEV_CLASS_ID_XXX

Changes from V2:

- fail when class_id is not specified
- drop the vringh patch
- match the doc to the code
- tweak the commit log
- move device_ops from parent to mdev device
- remove the unused MDEV_ID_VHOST

Changes from V1:

- move virtio_mdev.c to drivers/virtio
- store class_id in mdev_device instead of mdev_parent
- store device_ops in mdev_device instead of mdev_parent
- reorder the patch, vringh fix comes first
- really silent compiling warnings
- really switch to use u16 for class_id
- uevent and modpost support for mdev class_id
- vraious tweaks per comments from Parav

Changes from RFC-V2:

- silent compile warnings on some specific configuration
- use u16 instead u8 for class id
- reseve MDEV_ID_VHOST for future vhost-mdev work
- introduce "virtio" type for mvnet and make "vhost" type for future
  work
- add entries in MAINTAINER
- tweak and typos fixes in commit log

Changes from RFC-V1:

- rename device id to class id
- add docs for class id and device specific ops (device_ops)
- split device_ops into seperate headers
- drop the mdev_set_dma_ops()
- use device_ops to implement the transport API, then it's not a part
  of UAPI any more
- use GFP_ATOMIC in mvnet sample device and other tweaks
- set_vring_base/get_vring_base support for mvnet device

Jason Wang (6):
  mdev: class id support
  modpost: add support for mdev class id
  mdev: introduce device specific ops
  mdev: introduce virtio device and its device ops
  virtio: introduce a mdev based transport
  docs: sample driver to demonstrate how to implement virtio-mdev
    framework

 .../driver-api/vfio-mediated-device.rst       |  38 +-
 MAINTAINERS                                   |   2 +
 drivers/gpu/drm/i915/gvt/kvmgt.c              |  17 +-
 drivers/s390/cio/vfio_ccw_ops.c               |  17 +-
 drivers/s390/crypto/vfio_ap_ops.c             |  13 +-
 drivers/vfio/mdev/mdev_core.c                 |  59 ++
 drivers/vfio/mdev/mdev_driver.c               |  22 +
 drivers/vfio/mdev/mdev_private.h              |   8 +
 drivers/vfio/mdev/vfio_mdev.c                 |  45 +-
 drivers/virtio/Kconfig                        |   7 +
 drivers/virtio/Makefile                       |   1 +
 drivers/virtio/virtio_mdev.c                  | 413 +++++++++++
 include/linux/mdev.h                          |  57 +-
 include/linux/mod_devicetable.h               |   8 +
 include/linux/vfio_mdev_ops.h                 |  52 ++
 include/linux/virtio_mdev_ops.h               | 159 ++++
 samples/Kconfig                               |   7 +
 samples/vfio-mdev/Makefile                    |   1 +
 samples/vfio-mdev/mbochs.c                    |  19 +-
 samples/vfio-mdev/mdpy.c                      |  19 +-
 samples/vfio-mdev/mtty.c                      |  17 +-
 samples/vfio-mdev/mvnet.c                     | 691 ++++++++++++++++++
 scripts/mod/devicetable-offsets.c             |   3 +
 scripts/mod/file2alias.c                      |  10 +
 24 files changed, 1594 insertions(+), 91 deletions(-)
 create mode 100644 drivers/virtio/virtio_mdev.c
 create mode 100644 include/linux/vfio_mdev_ops.h
 create mode 100644 include/linux/virtio_mdev_ops.h
 create mode 100644 samples/vfio-mdev/mvnet.c

-- 
2.19.1

[PATCH V5 1/6] mdev: class id support

[Jason Wang]

Mdev bus only supports vfio driver right now, so it doesn't implement
match method. But in the future, we may add drivers other than vfio,
the first driver could be virtio-mdev. This means we need to add
device class id support in bus match method to pair the mdev device
and mdev driver correctly.

So this patch adds id_table to mdev_driver and class_id for mdev
device with the match method for mdev bus.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 .../driver-api/vfio-mediated-device.rst       |  5 +++++
 drivers/gpu/drm/i915/gvt/kvmgt.c              |  1 +
 drivers/s390/cio/vfio_ccw_ops.c               |  1 +
 drivers/s390/crypto/vfio_ap_ops.c             |  1 +
 drivers/vfio/mdev/mdev_core.c                 | 18 +++++++++++++++
 drivers/vfio/mdev/mdev_driver.c               | 22 +++++++++++++++++++
 drivers/vfio/mdev/mdev_private.h              |  1 +
 drivers/vfio/mdev/vfio_mdev.c                 |  6 +++++
 include/linux/mdev.h                          |  8 +++++++
 include/linux/mod_devicetable.h               |  8 +++++++
 samples/vfio-mdev/mbochs.c                    |  1 +
 samples/vfio-mdev/mdpy.c                      |  1 +
 samples/vfio-mdev/mtty.c                      |  1 +
 13 files changed, 74 insertions(+)

diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
index 25eb7d5b834b..6709413bee29 100644
--- a/Documentation/driver-api/vfio-mediated-device.rst
+++ b/Documentation/driver-api/vfio-mediated-device.rst
@@ -102,12 +102,14 @@ structure to represent a mediated device's driver::
       * @probe: called when new device created
       * @remove: called when device removed
       * @driver: device driver structure
+      * @id_table: the ids serviced by this driver
       */
      struct mdev_driver {
 	     const char *name;
 	     int  (*probe)  (struct device *dev);
 	     void (*remove) (struct device *dev);
 	     struct device_driver    driver;
+	     const struct mdev_class_id *id_table;
      };
 
 A mediated bus driver for mdev should use this structure in the function calls
@@ -170,6 +172,9 @@ that a driver should use to unregister itself with the mdev core driver::
 
 	extern void mdev_unregister_device(struct device *dev);
 
+It is also required to specify the class_id in create() callback through::
+
+	int mdev_set_class(struct mdev_device *mdev, u16 id);
 
 Mediated Device Management Interface Through sysfs
 ==================================================
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 343d79c1cb7e..6420f0dbd31b 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -678,6 +678,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
 		     dev_name(mdev_dev(mdev)));
 	ret = 0;
 
+	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
 out:
 	return ret;
 }
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index f0d71ab77c50..cf2c013ae32f 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -129,6 +129,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
 			   private->sch->schid.ssid,
 			   private->sch->schid.sch_no);
 
+	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
 	return 0;
 }
 
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 5c0f53c6dde7..07c31070afeb 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -343,6 +343,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
 	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
 	mutex_unlock(&matrix_dev->lock);
 
+	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
 	return 0;
 }
 
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index b558d4cfd082..3a9c52d71b4e 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -45,6 +45,16 @@ void mdev_set_drvdata(struct mdev_device *mdev, void *data)
 }
 EXPORT_SYMBOL(mdev_set_drvdata);
 
+/* Specify the class for the mdev device, this must be called during
+ * create() callback.
+ */
+void mdev_set_class(struct mdev_device *mdev, u16 id)
+{
+	WARN_ON(mdev->class_id);
+	mdev->class_id = id;
+}
+EXPORT_SYMBOL(mdev_set_class);
+
 struct device *mdev_dev(struct mdev_device *mdev)
 {
 	return &mdev->dev;
@@ -135,6 +145,7 @@ static int mdev_device_remove_cb(struct device *dev, void *data)
  * mdev_register_device : Register a device
  * @dev: device structure representing parent device.
  * @ops: Parent device operation structure to be registered.
+ * @id: class id.
  *
  * Add device to list of registered parent devices.
  * Returns a negative value on error, otherwise 0.
@@ -324,6 +335,13 @@ int mdev_device_create(struct kobject *kobj,
 	if (ret)
 		goto ops_create_fail;
 
+	if (!mdev->class_id) {
+		ret = -EINVAL;
+		WARN(1, "class id must be specified for device %s\n",
+		     dev_name(dev));
+		goto add_fail;
+	}
+
 	ret = device_add(&mdev->dev);
 	if (ret)
 		goto add_fail;
diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
index 0d3223aee20b..319d886ffaf7 100644
--- a/drivers/vfio/mdev/mdev_driver.c
+++ b/drivers/vfio/mdev/mdev_driver.c
@@ -69,8 +69,30 @@ static int mdev_remove(struct device *dev)
 	return 0;
 }
 
+static int mdev_match(struct device *dev, struct device_driver *drv)
+{
+	unsigned int i;
+	struct mdev_device *mdev = to_mdev_device(dev);
+	struct mdev_driver *mdrv = to_mdev_driver(drv);
+	const struct mdev_class_id *ids = mdrv->id_table;
+
+	for (i = 0; ids[i].id; i++)
+		if (ids[i].id == mdev->class_id)
+			return 1;
+	return 0;
+}
+
+static int mdev_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct mdev_device *mdev = to_mdev_device(dev);
+
+	return add_uevent_var(env, "MODALIAS=mdev:c%02X", mdev->class_id);
+}
+
 struct bus_type mdev_bus_type = {
 	.name		= "mdev",
+	.match		= mdev_match,
+	.uevent		= mdev_uevent,
 	.probe		= mdev_probe,
 	.remove		= mdev_remove,
 };
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index 7d922950caaf..c65f436c1869 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -33,6 +33,7 @@ struct mdev_device {
 	struct kobject *type_kobj;
 	struct device *iommu_device;
 	bool active;
+	u16 class_id;
 };
 
 #define to_mdev_device(dev)	container_of(dev, struct mdev_device, dev)
diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
index 30964a4e0a28..7b24ee9cb8dd 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -120,10 +120,16 @@ static void vfio_mdev_remove(struct device *dev)
 	vfio_del_group_dev(dev);
 }
 
+static const struct mdev_class_id id_table[] = {
+	{ MDEV_CLASS_ID_VFIO },
+	{ 0 },
+};
+
 static struct mdev_driver vfio_mdev_driver = {
 	.name	= "vfio_mdev",
 	.probe	= vfio_mdev_probe,
 	.remove	= vfio_mdev_remove,
+	.id_table = id_table,
 };
 
 static int __init vfio_mdev_init(void)
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index 0ce30ca78db0..78b69d09eb54 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -118,6 +118,7 @@ struct mdev_type_attribute mdev_type_attr_##_name =		\
  * @probe: called when new device created
  * @remove: called when device removed
  * @driver: device driver structure
+ * @id_table: the ids serviced by this driver
  *
  **/
 struct mdev_driver {
@@ -125,6 +126,7 @@ struct mdev_driver {
 	int  (*probe)(struct device *dev);
 	void (*remove)(struct device *dev);
 	struct device_driver driver;
+	const struct mdev_class_id *id_table;
 };
 
 #define to_mdev_driver(drv)	container_of(drv, struct mdev_driver, driver)
@@ -132,6 +134,7 @@ struct mdev_driver {
 void *mdev_get_drvdata(struct mdev_device *mdev);
 void mdev_set_drvdata(struct mdev_device *mdev, void *data);
 const guid_t *mdev_uuid(struct mdev_device *mdev);
+void mdev_set_class(struct mdev_device *mdev, u16 id);
 
 extern struct bus_type mdev_bus_type;
 
@@ -145,4 +148,9 @@ struct device *mdev_parent_dev(struct mdev_device *mdev);
 struct device *mdev_dev(struct mdev_device *mdev);
 struct mdev_device *mdev_from_dev(struct device *dev);
 
+enum {
+	MDEV_CLASS_ID_VFIO = 1,
+	/* New entries must be added here */
+};
+
 #endif /* MDEV_H */
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 5714fd35a83c..f32c6e44fb1a 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 device class identifier
+ * @id: Used to identify a specific class of device, e.g vfio-mdev device.
+ */
+struct mdev_class_id {
+	__u16 id;
+};
+
 #endif /* LINUX_MOD_DEVICETABLE_H */
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index ac5c8c17b1ff..115bc5074656 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -561,6 +561,7 @@ static int mbochs_create(struct kobject *kobj, struct mdev_device *mdev)
 	mbochs_reset(mdev);
 
 	mbochs_used_mbytes += type->mbytes;
+	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
 	return 0;
 
 err_mem:
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index cc86bf6566e4..665614574d50 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -269,6 +269,7 @@ static int mdpy_create(struct kobject *kobj, struct mdev_device *mdev)
 	mdpy_reset(mdev);
 
 	mdpy_count++;
+	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
 	return 0;
 }
 
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index ce84a300a4da..90da12ff7fd9 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -755,6 +755,7 @@ static int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
 	list_add(&mdev_state->next, &mdev_devices_list);
 	mutex_unlock(&mdev_list_lock);
 
+	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
 	return 0;
 }
 
-- 
2.19.1

RE: [PATCH V5 1/6] mdev: class id support

[Parav Pandit]

> -----Original Message-----
> From: Jason Wang <jasowang@redhat.com>
> Sent: Wednesday, October 23, 2019 8:08 AM
> To: kvm@vger.kernel.org; linux-s390@vger.kernel.org; linux-
> kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; intel-
> gfx@lists.freedesktop.org; intel-gvt-dev@lists.freedesktop.org;
> kwankhede@nvidia.com; alex.williamson@redhat.com; mst@redhat.com;
> tiwei.bie@intel.com
> Cc: virtualization@lists.linux-foundation.org; netdev@vger.kernel.org;
> cohuck@redhat.com; maxime.coquelin@redhat.com;
> cunming.liang@intel.com; zhihong.wang@intel.com;
> rob.miller@broadcom.com; xiao.w.wang@intel.com;
> haotian.wang@sifive.com; zhenyuw@linux.intel.com; zhi.a.wang@intel.com;
> jani.nikula@linux.intel.com; joonas.lahtinen@linux.intel.com;
> rodrigo.vivi@intel.com; airlied@linux.ie; daniel@ffwll.ch;
> farman@linux.ibm.com; pasic@linux.ibm.com; sebott@linux.ibm.com;
> oberpar@linux.ibm.com; heiko.carstens@de.ibm.com; gor@linux.ibm.com;
> borntraeger@de.ibm.com; akrowiak@linux.ibm.com; freude@linux.ibm.com;
> lingshan.zhu@intel.com; Ido Shamay <idos@mellanox.com>;
> eperezma@redhat.com; lulu@redhat.com; Parav Pandit
> <parav@mellanox.com>; christophe.de.dinechin@gmail.com;
> kevin.tian@intel.com; stefanha@redhat.com; Jason Wang
> <jasowang@redhat.com>
> Subject: [PATCH V5 1/6] mdev: class id support
> 
> Mdev bus only supports vfio driver right now, so it doesn't implement match
> method. But in the future, we may add drivers other than vfio, the first driver
> could be virtio-mdev. This means we need to add device class id support in bus
> match method to pair the mdev device and mdev driver correctly.
> 
> So this patch adds id_table to mdev_driver and class_id for mdev device with
> the match method for mdev bus.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  .../driver-api/vfio-mediated-device.rst       |  5 +++++
>  drivers/gpu/drm/i915/gvt/kvmgt.c              |  1 +
>  drivers/s390/cio/vfio_ccw_ops.c               |  1 +
>  drivers/s390/crypto/vfio_ap_ops.c             |  1 +
>  drivers/vfio/mdev/mdev_core.c                 | 18 +++++++++++++++
>  drivers/vfio/mdev/mdev_driver.c               | 22 +++++++++++++++++++
>  drivers/vfio/mdev/mdev_private.h              |  1 +
>  drivers/vfio/mdev/vfio_mdev.c                 |  6 +++++
>  include/linux/mdev.h                          |  8 +++++++
>  include/linux/mod_devicetable.h               |  8 +++++++
>  samples/vfio-mdev/mbochs.c                    |  1 +
>  samples/vfio-mdev/mdpy.c                      |  1 +
>  samples/vfio-mdev/mtty.c                      |  1 +
>  13 files changed, 74 insertions(+)
> 
> diff --git a/Documentation/driver-api/vfio-mediated-device.rst
> b/Documentation/driver-api/vfio-mediated-device.rst
> index 25eb7d5b834b..6709413bee29 100644
> --- a/Documentation/driver-api/vfio-mediated-device.rst
> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> @@ -102,12 +102,14 @@ structure to represent a mediated device's driver::
>        * @probe: called when new device created
>        * @remove: called when device removed
>        * @driver: device driver structure
> +      * @id_table: the ids serviced by this driver
>        */
>       struct mdev_driver {
>  	     const char *name;
>  	     int  (*probe)  (struct device *dev);
>  	     void (*remove) (struct device *dev);
>  	     struct device_driver    driver;
> +	     const struct mdev_class_id *id_table;
>       };
> 
>  A mediated bus driver for mdev should use this structure in the function calls
> @@ -170,6 +172,9 @@ that a driver should use to unregister itself with the
> mdev core driver::
> 
>  	extern void mdev_unregister_device(struct device *dev);
> 
> +It is also required to specify the class_id in create() callback through::
> +
> +	int mdev_set_class(struct mdev_device *mdev, u16 id);
> 
>  Mediated Device Management Interface Through sysfs
> ==================================================
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c
> b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 343d79c1cb7e..6420f0dbd31b 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -678,6 +678,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct
> mdev_device *mdev)
>  		     dev_name(mdev_dev(mdev)));
>  	ret = 0;
> 
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  out:
>  	return ret;
>  }
> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
> index f0d71ab77c50..cf2c013ae32f 100644
> --- a/drivers/s390/cio/vfio_ccw_ops.c
> +++ b/drivers/s390/cio/vfio_ccw_ops.c
> @@ -129,6 +129,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj,
> struct mdev_device *mdev)
>  			   private->sch->schid.ssid,
>  			   private->sch->schid.sch_no);
> 
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
>  }
> 
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
> b/drivers/s390/crypto/vfio_ap_ops.c
> index 5c0f53c6dde7..07c31070afeb 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -343,6 +343,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj,
> struct mdev_device *mdev)
>  	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
>  	mutex_unlock(&matrix_dev->lock);
> 
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
>  }
> 
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index b558d4cfd082..3a9c52d71b4e 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -45,6 +45,16 @@ void mdev_set_drvdata(struct mdev_device *mdev, void
> *data)  }  EXPORT_SYMBOL(mdev_set_drvdata);
> 
> +/* Specify the class for the mdev device, this must be called during
> + * create() callback.
> + */
> +void mdev_set_class(struct mdev_device *mdev, u16 id) {
> +	WARN_ON(mdev->class_id);
> +	mdev->class_id = id;
> +}
> +EXPORT_SYMBOL(mdev_set_class);
> +
>  struct device *mdev_dev(struct mdev_device *mdev)  {
>  	return &mdev->dev;
> @@ -135,6 +145,7 @@ static int mdev_device_remove_cb(struct device *dev,
> void *data)
>   * mdev_register_device : Register a device
>   * @dev: device structure representing parent device.
>   * @ops: Parent device operation structure to be registered.
> + * @id: class id.
>   *
>   * Add device to list of registered parent devices.
>   * Returns a negative value on error, otherwise 0.
> @@ -324,6 +335,13 @@ int mdev_device_create(struct kobject *kobj,
>  	if (ret)
>  		goto ops_create_fail;
> 
> +	if (!mdev->class_id) {
> +		ret = -EINVAL;
> +		WARN(1, "class id must be specified for device %s\n",
> +		     dev_name(dev));
> +		goto add_fail;
> +	}
> +
>  	ret = device_add(&mdev->dev);
>  	if (ret)
>  		goto add_fail;
> diff --git a/drivers/vfio/mdev/mdev_driver.c
> b/drivers/vfio/mdev/mdev_driver.c index 0d3223aee20b..319d886ffaf7 100644
> --- a/drivers/vfio/mdev/mdev_driver.c
> +++ b/drivers/vfio/mdev/mdev_driver.c
> @@ -69,8 +69,30 @@ static int mdev_remove(struct device *dev)
>  	return 0;
>  }
> 
> +static int mdev_match(struct device *dev, struct device_driver *drv) {
> +	unsigned int i;
> +	struct mdev_device *mdev = to_mdev_device(dev);
> +	struct mdev_driver *mdrv = to_mdev_driver(drv);
> +	const struct mdev_class_id *ids = mdrv->id_table;
> +
> +	for (i = 0; ids[i].id; i++)
> +		if (ids[i].id == mdev->class_id)
> +			return 1;
> +	return 0;
> +}
> +
> +static int mdev_uevent(struct device *dev, struct kobj_uevent_env *env)
> +{
> +	struct mdev_device *mdev = to_mdev_device(dev);
> +
> +	return add_uevent_var(env, "MODALIAS=mdev:c%02X", mdev-
> >class_id); }
> +
>  struct bus_type mdev_bus_type = {
>  	.name		= "mdev",
> +	.match		= mdev_match,
> +	.uevent		= mdev_uevent,
>  	.probe		= mdev_probe,
>  	.remove		= mdev_remove,
>  };
> diff --git a/drivers/vfio/mdev/mdev_private.h
> b/drivers/vfio/mdev/mdev_private.h
> index 7d922950caaf..c65f436c1869 100644
> --- a/drivers/vfio/mdev/mdev_private.h
> +++ b/drivers/vfio/mdev/mdev_private.h
> @@ -33,6 +33,7 @@ struct mdev_device {
>  	struct kobject *type_kobj;
>  	struct device *iommu_device;
>  	bool active;
> +	u16 class_id;
>  };
> 
>  #define to_mdev_device(dev)	container_of(dev, struct mdev_device, dev)
> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
> index 30964a4e0a28..7b24ee9cb8dd 100644
> --- a/drivers/vfio/mdev/vfio_mdev.c
> +++ b/drivers/vfio/mdev/vfio_mdev.c
> @@ -120,10 +120,16 @@ static void vfio_mdev_remove(struct device *dev)
>  	vfio_del_group_dev(dev);
>  }
> 
> +static const struct mdev_class_id id_table[] = {
> +	{ MDEV_CLASS_ID_VFIO },
> +	{ 0 },
> +};
> +
>  static struct mdev_driver vfio_mdev_driver = {
>  	.name	= "vfio_mdev",
>  	.probe	= vfio_mdev_probe,
>  	.remove	= vfio_mdev_remove,
> +	.id_table = id_table,
>  };
> 
>  static int __init vfio_mdev_init(void)
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h index
> 0ce30ca78db0..78b69d09eb54 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -118,6 +118,7 @@ struct mdev_type_attribute mdev_type_attr_##_name
> =		\
>   * @probe: called when new device created
>   * @remove: called when device removed
>   * @driver: device driver structure
> + * @id_table: the ids serviced by this driver
>   *
>   **/
>  struct mdev_driver {
> @@ -125,6 +126,7 @@ struct mdev_driver {
>  	int  (*probe)(struct device *dev);
>  	void (*remove)(struct device *dev);
>  	struct device_driver driver;
> +	const struct mdev_class_id *id_table;
>  };
> 
>  #define to_mdev_driver(drv)	container_of(drv, struct mdev_driver, driver)
> @@ -132,6 +134,7 @@ struct mdev_driver {  void *mdev_get_drvdata(struct
> mdev_device *mdev);  void mdev_set_drvdata(struct mdev_device *mdev, void
> *data);  const guid_t *mdev_uuid(struct mdev_device *mdev);
> +void mdev_set_class(struct mdev_device *mdev, u16 id);
> 
>  extern struct bus_type mdev_bus_type;
> 
> @@ -145,4 +148,9 @@ struct device *mdev_parent_dev(struct mdev_device
> *mdev);  struct device *mdev_dev(struct mdev_device *mdev);  struct
> mdev_device *mdev_from_dev(struct device *dev);
> 
> +enum {
> +	MDEV_CLASS_ID_VFIO = 1,
> +	/* New entries must be added here */
> +};
> +
>  #endif /* MDEV_H */
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index 5714fd35a83c..f32c6e44fb1a 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 device class identifier
> + * @id: Used to identify a specific class of device, e.g vfio-mdev device.
> + */
> +struct mdev_class_id {
> +	__u16 id;
> +};
> +
>  #endif /* LINUX_MOD_DEVICETABLE_H */
> diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c index
> ac5c8c17b1ff..115bc5074656 100644
> --- a/samples/vfio-mdev/mbochs.c
> +++ b/samples/vfio-mdev/mbochs.c
> @@ -561,6 +561,7 @@ static int mbochs_create(struct kobject *kobj, struct
> mdev_device *mdev)
>  	mbochs_reset(mdev);
> 
>  	mbochs_used_mbytes += type->mbytes;
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
> 
>  err_mem:
> diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c index
> cc86bf6566e4..665614574d50 100644
> --- a/samples/vfio-mdev/mdpy.c
> +++ b/samples/vfio-mdev/mdpy.c
> @@ -269,6 +269,7 @@ static int mdpy_create(struct kobject *kobj, struct
> mdev_device *mdev)
>  	mdpy_reset(mdev);
> 
>  	mdpy_count++;
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
>  }
> 
> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c index
> ce84a300a4da..90da12ff7fd9 100644
> --- a/samples/vfio-mdev/mtty.c
> +++ b/samples/vfio-mdev/mtty.c
> @@ -755,6 +755,7 @@ static int mtty_create(struct kobject *kobj, struct
> mdev_device *mdev)
>  	list_add(&mdev_state->next, &mdev_devices_list);
>  	mutex_unlock(&mdev_list_lock);
> 
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
>  }
> 
> --
> 2.19.1
Reviewed-by: Parav Pandit <parav@mellanox.com>

Re: [PATCH V5 1/6] mdev: class id support

[Alex Williamson]

On Wed, 23 Oct 2019 21:07:47 +0800
Jason Wang <jasowang@redhat.com> wrote:

> Mdev bus only supports vfio driver right now, so it doesn't implement
> match method. But in the future, we may add drivers other than vfio,
> the first driver could be virtio-mdev. This means we need to add
> device class id support in bus match method to pair the mdev device
> and mdev driver correctly.
> 
> So this patch adds id_table to mdev_driver and class_id for mdev
> device with the match method for mdev bus.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  .../driver-api/vfio-mediated-device.rst       |  5 +++++
>  drivers/gpu/drm/i915/gvt/kvmgt.c              |  1 +
>  drivers/s390/cio/vfio_ccw_ops.c               |  1 +
>  drivers/s390/crypto/vfio_ap_ops.c             |  1 +
>  drivers/vfio/mdev/mdev_core.c                 | 18 +++++++++++++++
>  drivers/vfio/mdev/mdev_driver.c               | 22 +++++++++++++++++++
>  drivers/vfio/mdev/mdev_private.h              |  1 +
>  drivers/vfio/mdev/vfio_mdev.c                 |  6 +++++
>  include/linux/mdev.h                          |  8 +++++++
>  include/linux/mod_devicetable.h               |  8 +++++++
>  samples/vfio-mdev/mbochs.c                    |  1 +
>  samples/vfio-mdev/mdpy.c                      |  1 +
>  samples/vfio-mdev/mtty.c                      |  1 +
>  13 files changed, 74 insertions(+)
> 
> diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
> index 25eb7d5b834b..6709413bee29 100644
> --- a/Documentation/driver-api/vfio-mediated-device.rst
> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> @@ -102,12 +102,14 @@ structure to represent a mediated device's driver::
>        * @probe: called when new device created
>        * @remove: called when device removed
>        * @driver: device driver structure
> +      * @id_table: the ids serviced by this driver
>        */
>       struct mdev_driver {
>  	     const char *name;
>  	     int  (*probe)  (struct device *dev);
>  	     void (*remove) (struct device *dev);
>  	     struct device_driver    driver;
> +	     const struct mdev_class_id *id_table;
>       };
>  
>  A mediated bus driver for mdev should use this structure in the function calls
> @@ -170,6 +172,9 @@ that a driver should use to unregister itself with the mdev core driver::
>  
>  	extern void mdev_unregister_device(struct device *dev);
>  
> +It is also required to specify the class_id in create() callback through::
> +
> +	int mdev_set_class(struct mdev_device *mdev, u16 id);
>  
>  Mediated Device Management Interface Through sysfs
>  ==================================================
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index 343d79c1cb7e..6420f0dbd31b 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -678,6 +678,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
>  		     dev_name(mdev_dev(mdev)));
>  	ret = 0;
>  
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  out:
>  	return ret;
>  }
> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
> index f0d71ab77c50..cf2c013ae32f 100644
> --- a/drivers/s390/cio/vfio_ccw_ops.c
> +++ b/drivers/s390/cio/vfio_ccw_ops.c
> @@ -129,6 +129,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>  			   private->sch->schid.ssid,
>  			   private->sch->schid.sch_no);
>  
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
>  }
>  
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 5c0f53c6dde7..07c31070afeb 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -343,6 +343,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>  	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
>  	mutex_unlock(&matrix_dev->lock);
>  
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
>  }
>  
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index b558d4cfd082..3a9c52d71b4e 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -45,6 +45,16 @@ void mdev_set_drvdata(struct mdev_device *mdev, void *data)
>  }
>  EXPORT_SYMBOL(mdev_set_drvdata);
>  
> +/* Specify the class for the mdev device, this must be called during
> + * create() callback.
> + */
> +void mdev_set_class(struct mdev_device *mdev, u16 id)
> +{
> +	WARN_ON(mdev->class_id);
> +	mdev->class_id = id;
> +}
> +EXPORT_SYMBOL(mdev_set_class);
> +
>  struct device *mdev_dev(struct mdev_device *mdev)
>  {
>  	return &mdev->dev;
> @@ -135,6 +145,7 @@ static int mdev_device_remove_cb(struct device *dev, void *data)
>   * mdev_register_device : Register a device
>   * @dev: device structure representing parent device.
>   * @ops: Parent device operation structure to be registered.
> + * @id: class id.
>   *
>   * Add device to list of registered parent devices.
>   * Returns a negative value on error, otherwise 0.
> @@ -324,6 +335,13 @@ int mdev_device_create(struct kobject *kobj,
>  	if (ret)
>  		goto ops_create_fail;
>  
> +	if (!mdev->class_id) {
> +		ret = -EINVAL;
> +		WARN(1, "class id must be specified for device %s\n",
> +		     dev_name(dev));

Nit, dev_warn(dev, "mdev vendor driver failed to specify device class\n");

> +		goto add_fail;
> +	}
> +
>  	ret = device_add(&mdev->dev);
>  	if (ret)
>  		goto add_fail;
> diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
> index 0d3223aee20b..319d886ffaf7 100644
> --- a/drivers/vfio/mdev/mdev_driver.c
> +++ b/drivers/vfio/mdev/mdev_driver.c
> @@ -69,8 +69,30 @@ static int mdev_remove(struct device *dev)
>  	return 0;
>  }
>  
> +static int mdev_match(struct device *dev, struct device_driver *drv)
> +{
> +	unsigned int i;
> +	struct mdev_device *mdev = to_mdev_device(dev);
> +	struct mdev_driver *mdrv = to_mdev_driver(drv);
> +	const struct mdev_class_id *ids = mdrv->id_table;
> +

Nit, as we start to allow new mdev bus drivers, mdev-core might want to
protect itself from a NULL id_table, by either failing the
mdev_register_driver() or failing the match here.  I think such a
condition would segfault as written here, but clearly we don't have
such external drivers yet.  Thanks,

Alex

> +	for (i = 0; ids[i].id; i++)
> +		if (ids[i].id == mdev->class_id)
> +			return 1;
> +	return 0;
> +}
> +
> +static int mdev_uevent(struct device *dev, struct kobj_uevent_env *env)
> +{
> +	struct mdev_device *mdev = to_mdev_device(dev);
> +
> +	return add_uevent_var(env, "MODALIAS=mdev:c%02X", mdev->class_id);
> +}
> +
>  struct bus_type mdev_bus_type = {
>  	.name		= "mdev",
> +	.match		= mdev_match,
> +	.uevent		= mdev_uevent,
>  	.probe		= mdev_probe,
>  	.remove		= mdev_remove,
>  };
> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
> index 7d922950caaf..c65f436c1869 100644
> --- a/drivers/vfio/mdev/mdev_private.h
> +++ b/drivers/vfio/mdev/mdev_private.h
> @@ -33,6 +33,7 @@ struct mdev_device {
>  	struct kobject *type_kobj;
>  	struct device *iommu_device;
>  	bool active;
> +	u16 class_id;
>  };
>  
>  #define to_mdev_device(dev)	container_of(dev, struct mdev_device, dev)
> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
> index 30964a4e0a28..7b24ee9cb8dd 100644
> --- a/drivers/vfio/mdev/vfio_mdev.c
> +++ b/drivers/vfio/mdev/vfio_mdev.c
> @@ -120,10 +120,16 @@ static void vfio_mdev_remove(struct device *dev)
>  	vfio_del_group_dev(dev);
>  }
>  
> +static const struct mdev_class_id id_table[] = {
> +	{ MDEV_CLASS_ID_VFIO },
> +	{ 0 },
> +};
> +
>  static struct mdev_driver vfio_mdev_driver = {
>  	.name	= "vfio_mdev",
>  	.probe	= vfio_mdev_probe,
>  	.remove	= vfio_mdev_remove,
> +	.id_table = id_table,
>  };
>  
>  static int __init vfio_mdev_init(void)
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 0ce30ca78db0..78b69d09eb54 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -118,6 +118,7 @@ struct mdev_type_attribute mdev_type_attr_##_name =		\
>   * @probe: called when new device created
>   * @remove: called when device removed
>   * @driver: device driver structure
> + * @id_table: the ids serviced by this driver
>   *
>   **/
>  struct mdev_driver {
> @@ -125,6 +126,7 @@ struct mdev_driver {
>  	int  (*probe)(struct device *dev);
>  	void (*remove)(struct device *dev);
>  	struct device_driver driver;
> +	const struct mdev_class_id *id_table;
>  };
>  
>  #define to_mdev_driver(drv)	container_of(drv, struct mdev_driver, driver)
> @@ -132,6 +134,7 @@ struct mdev_driver {
>  void *mdev_get_drvdata(struct mdev_device *mdev);
>  void mdev_set_drvdata(struct mdev_device *mdev, void *data);
>  const guid_t *mdev_uuid(struct mdev_device *mdev);
> +void mdev_set_class(struct mdev_device *mdev, u16 id);
>  
>  extern struct bus_type mdev_bus_type;
>  
> @@ -145,4 +148,9 @@ struct device *mdev_parent_dev(struct mdev_device *mdev);
>  struct device *mdev_dev(struct mdev_device *mdev);
>  struct mdev_device *mdev_from_dev(struct device *dev);
>  
> +enum {
> +	MDEV_CLASS_ID_VFIO = 1,
> +	/* New entries must be added here */
> +};
> +
>  #endif /* MDEV_H */
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index 5714fd35a83c..f32c6e44fb1a 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 device class identifier
> + * @id: Used to identify a specific class of device, e.g vfio-mdev device.
> + */
> +struct mdev_class_id {
> +	__u16 id;
> +};
> +
>  #endif /* LINUX_MOD_DEVICETABLE_H */
> diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
> index ac5c8c17b1ff..115bc5074656 100644
> --- a/samples/vfio-mdev/mbochs.c
> +++ b/samples/vfio-mdev/mbochs.c
> @@ -561,6 +561,7 @@ static int mbochs_create(struct kobject *kobj, struct mdev_device *mdev)
>  	mbochs_reset(mdev);
>  
>  	mbochs_used_mbytes += type->mbytes;
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
>  
>  err_mem:
> diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
> index cc86bf6566e4..665614574d50 100644
> --- a/samples/vfio-mdev/mdpy.c
> +++ b/samples/vfio-mdev/mdpy.c
> @@ -269,6 +269,7 @@ static int mdpy_create(struct kobject *kobj, struct mdev_device *mdev)
>  	mdpy_reset(mdev);
>  
>  	mdpy_count++;
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
>  }
>  
> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
> index ce84a300a4da..90da12ff7fd9 100644
> --- a/samples/vfio-mdev/mtty.c
> +++ b/samples/vfio-mdev/mtty.c
> @@ -755,6 +755,7 @@ static int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
>  	list_add(&mdev_state->next, &mdev_devices_list);
>  	mutex_unlock(&mdev_list_lock);
>  
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>  	return 0;
>  }
>  

Re: [PATCH V5 1/6] mdev: class id support

[Jason Wang]

On 2019/10/24 上午5:42, Alex Williamson wrote:
> On Wed, 23 Oct 2019 21:07:47 +0800
> Jason Wang <jasowang@redhat.com> wrote:
>
>> Mdev bus only supports vfio driver right now, so it doesn't implement
>> match method. But in the future, we may add drivers other than vfio,
>> the first driver could be virtio-mdev. This means we need to add
>> device class id support in bus match method to pair the mdev device
>> and mdev driver correctly.
>>
>> So this patch adds id_table to mdev_driver and class_id for mdev
>> device with the match method for mdev bus.
>>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>   .../driver-api/vfio-mediated-device.rst       |  5 +++++
>>   drivers/gpu/drm/i915/gvt/kvmgt.c              |  1 +
>>   drivers/s390/cio/vfio_ccw_ops.c               |  1 +
>>   drivers/s390/crypto/vfio_ap_ops.c             |  1 +
>>   drivers/vfio/mdev/mdev_core.c                 | 18 +++++++++++++++
>>   drivers/vfio/mdev/mdev_driver.c               | 22 +++++++++++++++++++
>>   drivers/vfio/mdev/mdev_private.h              |  1 +
>>   drivers/vfio/mdev/vfio_mdev.c                 |  6 +++++
>>   include/linux/mdev.h                          |  8 +++++++
>>   include/linux/mod_devicetable.h               |  8 +++++++
>>   samples/vfio-mdev/mbochs.c                    |  1 +
>>   samples/vfio-mdev/mdpy.c                      |  1 +
>>   samples/vfio-mdev/mtty.c                      |  1 +
>>   13 files changed, 74 insertions(+)
>>
>> diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
>> index 25eb7d5b834b..6709413bee29 100644
>> --- a/Documentation/driver-api/vfio-mediated-device.rst
>> +++ b/Documentation/driver-api/vfio-mediated-device.rst
>> @@ -102,12 +102,14 @@ structure to represent a mediated device's driver::
>>         * @probe: called when new device created
>>         * @remove: called when device removed
>>         * @driver: device driver structure
>> +      * @id_table: the ids serviced by this driver
>>         */
>>        struct mdev_driver {
>>   	     const char *name;
>>   	     int  (*probe)  (struct device *dev);
>>   	     void (*remove) (struct device *dev);
>>   	     struct device_driver    driver;
>> +	     const struct mdev_class_id *id_table;
>>        };
>>   
>>   A mediated bus driver for mdev should use this structure in the function calls
>> @@ -170,6 +172,9 @@ that a driver should use to unregister itself with the mdev core driver::
>>   
>>   	extern void mdev_unregister_device(struct device *dev);
>>   
>> +It is also required to specify the class_id in create() callback through::
>> +
>> +	int mdev_set_class(struct mdev_device *mdev, u16 id);
>>   
>>   Mediated Device Management Interface Through sysfs
>>   ==================================================
>> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> index 343d79c1cb7e..6420f0dbd31b 100644
>> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
>> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> @@ -678,6 +678,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
>>   		     dev_name(mdev_dev(mdev)));
>>   	ret = 0;
>>   
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   out:
>>   	return ret;
>>   }
>> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
>> index f0d71ab77c50..cf2c013ae32f 100644
>> --- a/drivers/s390/cio/vfio_ccw_ops.c
>> +++ b/drivers/s390/cio/vfio_ccw_ops.c
>> @@ -129,6 +129,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>>   			   private->sch->schid.ssid,
>>   			   private->sch->schid.sch_no);
>>   
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   }
>>   
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
>> index 5c0f53c6dde7..07c31070afeb 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -343,6 +343,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>>   	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
>>   	mutex_unlock(&matrix_dev->lock);
>>   
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   }
>>   
>> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
>> index b558d4cfd082..3a9c52d71b4e 100644
>> --- a/drivers/vfio/mdev/mdev_core.c
>> +++ b/drivers/vfio/mdev/mdev_core.c
>> @@ -45,6 +45,16 @@ void mdev_set_drvdata(struct mdev_device *mdev, void *data)
>>   }
>>   EXPORT_SYMBOL(mdev_set_drvdata);
>>   
>> +/* Specify the class for the mdev device, this must be called during
>> + * create() callback.
>> + */
>> +void mdev_set_class(struct mdev_device *mdev, u16 id)
>> +{
>> +	WARN_ON(mdev->class_id);
>> +	mdev->class_id = id;
>> +}
>> +EXPORT_SYMBOL(mdev_set_class);
>> +
>>   struct device *mdev_dev(struct mdev_device *mdev)
>>   {
>>   	return &mdev->dev;
>> @@ -135,6 +145,7 @@ static int mdev_device_remove_cb(struct device *dev, void *data)
>>    * mdev_register_device : Register a device
>>    * @dev: device structure representing parent device.
>>    * @ops: Parent device operation structure to be registered.
>> + * @id: class id.
>>    *
>>    * Add device to list of registered parent devices.
>>    * Returns a negative value on error, otherwise 0.
>> @@ -324,6 +335,13 @@ int mdev_device_create(struct kobject *kobj,
>>   	if (ret)
>>   		goto ops_create_fail;
>>   
>> +	if (!mdev->class_id) {
>> +		ret = -EINVAL;
>> +		WARN(1, "class id must be specified for device %s\n",
>> +		     dev_name(dev));
> Nit, dev_warn(dev, "mdev vendor driver failed to specify device class\n");


Will fix.


>
>> +		goto add_fail;
>> +	}
>> +
>>   	ret = device_add(&mdev->dev);
>>   	if (ret)
>>   		goto add_fail;
>> diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
>> index 0d3223aee20b..319d886ffaf7 100644
>> --- a/drivers/vfio/mdev/mdev_driver.c
>> +++ b/drivers/vfio/mdev/mdev_driver.c
>> @@ -69,8 +69,30 @@ static int mdev_remove(struct device *dev)
>>   	return 0;
>>   }
>>   
>> +static int mdev_match(struct device *dev, struct device_driver *drv)
>> +{
>> +	unsigned int i;
>> +	struct mdev_device *mdev = to_mdev_device(dev);
>> +	struct mdev_driver *mdrv = to_mdev_driver(drv);
>> +	const struct mdev_class_id *ids = mdrv->id_table;
>> +
> Nit, as we start to allow new mdev bus drivers, mdev-core might want to
> protect itself from a NULL id_table, by either failing the
> mdev_register_driver() or failing the match here.  I think such a
> condition would segfault as written here, but clearly we don't have
> such external drivers yet.  Thanks,


I'm not sure I get the point here. My understanding is that mdev-core 
won't try to be matched here since it was not a complete mdev device.

Thanks


>
> Alex
>
>> +	for (i = 0; ids[i].id; i++)
>> +		if (ids[i].id == mdev->class_id)
>> +			return 1;
>> +	return 0;
>> +}
>> +
>> +static int mdev_uevent(struct device *dev, struct kobj_uevent_env *env)
>> +{
>> +	struct mdev_device *mdev = to_mdev_device(dev);
>> +
>> +	return add_uevent_var(env, "MODALIAS=mdev:c%02X", mdev->class_id);
>> +}
>> +
>>   struct bus_type mdev_bus_type = {
>>   	.name		= "mdev",
>> +	.match		= mdev_match,
>> +	.uevent		= mdev_uevent,
>>   	.probe		= mdev_probe,
>>   	.remove		= mdev_remove,
>>   };
>> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
>> index 7d922950caaf..c65f436c1869 100644
>> --- a/drivers/vfio/mdev/mdev_private.h
>> +++ b/drivers/vfio/mdev/mdev_private.h
>> @@ -33,6 +33,7 @@ struct mdev_device {
>>   	struct kobject *type_kobj;
>>   	struct device *iommu_device;
>>   	bool active;
>> +	u16 class_id;
>>   };
>>   
>>   #define to_mdev_device(dev)	container_of(dev, struct mdev_device, dev)
>> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
>> index 30964a4e0a28..7b24ee9cb8dd 100644
>> --- a/drivers/vfio/mdev/vfio_mdev.c
>> +++ b/drivers/vfio/mdev/vfio_mdev.c
>> @@ -120,10 +120,16 @@ static void vfio_mdev_remove(struct device *dev)
>>   	vfio_del_group_dev(dev);
>>   }
>>   
>> +static const struct mdev_class_id id_table[] = {
>> +	{ MDEV_CLASS_ID_VFIO },
>> +	{ 0 },
>> +};
>> +
>>   static struct mdev_driver vfio_mdev_driver = {
>>   	.name	= "vfio_mdev",
>>   	.probe	= vfio_mdev_probe,
>>   	.remove	= vfio_mdev_remove,
>> +	.id_table = id_table,
>>   };
>>   
>>   static int __init vfio_mdev_init(void)
>> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
>> index 0ce30ca78db0..78b69d09eb54 100644
>> --- a/include/linux/mdev.h
>> +++ b/include/linux/mdev.h
>> @@ -118,6 +118,7 @@ struct mdev_type_attribute mdev_type_attr_##_name =		\
>>    * @probe: called when new device created
>>    * @remove: called when device removed
>>    * @driver: device driver structure
>> + * @id_table: the ids serviced by this driver
>>    *
>>    **/
>>   struct mdev_driver {
>> @@ -125,6 +126,7 @@ struct mdev_driver {
>>   	int  (*probe)(struct device *dev);
>>   	void (*remove)(struct device *dev);
>>   	struct device_driver driver;
>> +	const struct mdev_class_id *id_table;
>>   };
>>   
>>   #define to_mdev_driver(drv)	container_of(drv, struct mdev_driver, driver)
>> @@ -132,6 +134,7 @@ struct mdev_driver {
>>   void *mdev_get_drvdata(struct mdev_device *mdev);
>>   void mdev_set_drvdata(struct mdev_device *mdev, void *data);
>>   const guid_t *mdev_uuid(struct mdev_device *mdev);
>> +void mdev_set_class(struct mdev_device *mdev, u16 id);
>>   
>>   extern struct bus_type mdev_bus_type;
>>   
>> @@ -145,4 +148,9 @@ struct device *mdev_parent_dev(struct mdev_device *mdev);
>>   struct device *mdev_dev(struct mdev_device *mdev);
>>   struct mdev_device *mdev_from_dev(struct device *dev);
>>   
>> +enum {
>> +	MDEV_CLASS_ID_VFIO = 1,
>> +	/* New entries must be added here */
>> +};
>> +
>>   #endif /* MDEV_H */
>> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
>> index 5714fd35a83c..f32c6e44fb1a 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 device class identifier
>> + * @id: Used to identify a specific class of device, e.g vfio-mdev device.
>> + */
>> +struct mdev_class_id {
>> +	__u16 id;
>> +};
>> +
>>   #endif /* LINUX_MOD_DEVICETABLE_H */
>> diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
>> index ac5c8c17b1ff..115bc5074656 100644
>> --- a/samples/vfio-mdev/mbochs.c
>> +++ b/samples/vfio-mdev/mbochs.c
>> @@ -561,6 +561,7 @@ static int mbochs_create(struct kobject *kobj, struct mdev_device *mdev)
>>   	mbochs_reset(mdev);
>>   
>>   	mbochs_used_mbytes += type->mbytes;
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   
>>   err_mem:
>> diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
>> index cc86bf6566e4..665614574d50 100644
>> --- a/samples/vfio-mdev/mdpy.c
>> +++ b/samples/vfio-mdev/mdpy.c
>> @@ -269,6 +269,7 @@ static int mdpy_create(struct kobject *kobj, struct mdev_device *mdev)
>>   	mdpy_reset(mdev);
>>   
>>   	mdpy_count++;
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   }
>>   
>> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
>> index ce84a300a4da..90da12ff7fd9 100644
>> --- a/samples/vfio-mdev/mtty.c
>> +++ b/samples/vfio-mdev/mtty.c
>> @@ -755,6 +755,7 @@ static int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
>>   	list_add(&mdev_state->next, &mdev_devices_list);
>>   	mutex_unlock(&mdev_list_lock);
>>   
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>   	return 0;
>>   }
>>   

Re: [PATCH V5 1/6] mdev: class id support

[Alex Williamson]

On Thu, 24 Oct 2019 11:27:36 +0800
Jason Wang <jasowang@redhat.com> wrote:

> On 2019/10/24 上午5:42, Alex Williamson wrote:
> > On Wed, 23 Oct 2019 21:07:47 +0800
> > Jason Wang <jasowang@redhat.com> wrote:
> >  
> >> Mdev bus only supports vfio driver right now, so it doesn't implement
> >> match method. But in the future, we may add drivers other than vfio,
> >> the first driver could be virtio-mdev. This means we need to add
> >> device class id support in bus match method to pair the mdev device
> >> and mdev driver correctly.
> >>
> >> So this patch adds id_table to mdev_driver and class_id for mdev
> >> device with the match method for mdev bus.
> >>
> >> Signed-off-by: Jason Wang <jasowang@redhat.com>
> >> ---
> >>   .../driver-api/vfio-mediated-device.rst       |  5 +++++
> >>   drivers/gpu/drm/i915/gvt/kvmgt.c              |  1 +
> >>   drivers/s390/cio/vfio_ccw_ops.c               |  1 +
> >>   drivers/s390/crypto/vfio_ap_ops.c             |  1 +
> >>   drivers/vfio/mdev/mdev_core.c                 | 18 +++++++++++++++
> >>   drivers/vfio/mdev/mdev_driver.c               | 22 +++++++++++++++++++
> >>   drivers/vfio/mdev/mdev_private.h              |  1 +
> >>   drivers/vfio/mdev/vfio_mdev.c                 |  6 +++++
> >>   include/linux/mdev.h                          |  8 +++++++
> >>   include/linux/mod_devicetable.h               |  8 +++++++
> >>   samples/vfio-mdev/mbochs.c                    |  1 +
> >>   samples/vfio-mdev/mdpy.c                      |  1 +
> >>   samples/vfio-mdev/mtty.c                      |  1 +
> >>   13 files changed, 74 insertions(+)
> >>
> >> diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
> >> index 25eb7d5b834b..6709413bee29 100644
> >> --- a/Documentation/driver-api/vfio-mediated-device.rst
> >> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> >> @@ -102,12 +102,14 @@ structure to represent a mediated device's driver::
> >>         * @probe: called when new device created
> >>         * @remove: called when device removed
> >>         * @driver: device driver structure
> >> +      * @id_table: the ids serviced by this driver
> >>         */
> >>        struct mdev_driver {
> >>   	     const char *name;
> >>   	     int  (*probe)  (struct device *dev);
> >>   	     void (*remove) (struct device *dev);
> >>   	     struct device_driver    driver;
> >> +	     const struct mdev_class_id *id_table;
> >>        };
> >>   
> >>   A mediated bus driver for mdev should use this structure in the function calls
> >> @@ -170,6 +172,9 @@ that a driver should use to unregister itself with the mdev core driver::
> >>   
> >>   	extern void mdev_unregister_device(struct device *dev);
> >>   
> >> +It is also required to specify the class_id in create() callback through::
> >> +
> >> +	int mdev_set_class(struct mdev_device *mdev, u16 id);
> >>   
> >>   Mediated Device Management Interface Through sysfs
> >>   ==================================================
> >> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> >> index 343d79c1cb7e..6420f0dbd31b 100644
> >> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> >> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> >> @@ -678,6 +678,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
> >>   		     dev_name(mdev_dev(mdev)));
> >>   	ret = 0;
> >>   
> >> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> >>   out:
> >>   	return ret;
> >>   }
> >> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
> >> index f0d71ab77c50..cf2c013ae32f 100644
> >> --- a/drivers/s390/cio/vfio_ccw_ops.c
> >> +++ b/drivers/s390/cio/vfio_ccw_ops.c
> >> @@ -129,6 +129,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
> >>   			   private->sch->schid.ssid,
> >>   			   private->sch->schid.sch_no);
> >>   
> >> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> >>   	return 0;
> >>   }
> >>   
> >> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> >> index 5c0f53c6dde7..07c31070afeb 100644
> >> --- a/drivers/s390/crypto/vfio_ap_ops.c
> >> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> >> @@ -343,6 +343,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
> >>   	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
> >>   	mutex_unlock(&matrix_dev->lock);
> >>   
> >> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> >>   	return 0;
> >>   }
> >>   
> >> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> >> index b558d4cfd082..3a9c52d71b4e 100644
> >> --- a/drivers/vfio/mdev/mdev_core.c
> >> +++ b/drivers/vfio/mdev/mdev_core.c
> >> @@ -45,6 +45,16 @@ void mdev_set_drvdata(struct mdev_device *mdev, void *data)
> >>   }
> >>   EXPORT_SYMBOL(mdev_set_drvdata);
> >>   
> >> +/* Specify the class for the mdev device, this must be called during
> >> + * create() callback.
> >> + */
> >> +void mdev_set_class(struct mdev_device *mdev, u16 id)
> >> +{
> >> +	WARN_ON(mdev->class_id);
> >> +	mdev->class_id = id;
> >> +}
> >> +EXPORT_SYMBOL(mdev_set_class);
> >> +
> >>   struct device *mdev_dev(struct mdev_device *mdev)
> >>   {
> >>   	return &mdev->dev;
> >> @@ -135,6 +145,7 @@ static int mdev_device_remove_cb(struct device *dev, void *data)
> >>    * mdev_register_device : Register a device
> >>    * @dev: device structure representing parent device.
> >>    * @ops: Parent device operation structure to be registered.
> >> + * @id: class id.
> >>    *
> >>    * Add device to list of registered parent devices.
> >>    * Returns a negative value on error, otherwise 0.
> >> @@ -324,6 +335,13 @@ int mdev_device_create(struct kobject *kobj,
> >>   	if (ret)
> >>   		goto ops_create_fail;
> >>   
> >> +	if (!mdev->class_id) {
> >> +		ret = -EINVAL;
> >> +		WARN(1, "class id must be specified for device %s\n",
> >> +		     dev_name(dev));  
> > Nit, dev_warn(dev, "mdev vendor driver failed to specify device class\n");  
> 
> 
> Will fix.
> 
> 
> >  
> >> +		goto add_fail;
> >> +	}
> >> +
> >>   	ret = device_add(&mdev->dev);
> >>   	if (ret)
> >>   		goto add_fail;
> >> diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
> >> index 0d3223aee20b..319d886ffaf7 100644
> >> --- a/drivers/vfio/mdev/mdev_driver.c
> >> +++ b/drivers/vfio/mdev/mdev_driver.c
> >> @@ -69,8 +69,30 @@ static int mdev_remove(struct device *dev)
> >>   	return 0;
> >>   }
> >>   
> >> +static int mdev_match(struct device *dev, struct device_driver *drv)
> >> +{
> >> +	unsigned int i;
> >> +	struct mdev_device *mdev = to_mdev_device(dev);
> >> +	struct mdev_driver *mdrv = to_mdev_driver(drv);
> >> +	const struct mdev_class_id *ids = mdrv->id_table;
> >> +  
> > Nit, as we start to allow new mdev bus drivers, mdev-core might want to
> > protect itself from a NULL id_table, by either failing the
> > mdev_register_driver() or failing the match here.  I think such a
> > condition would segfault as written here, but clearly we don't have
> > such external drivers yet.  Thanks,  
> 
> 
> I'm not sure I get the point here. My understanding is that mdev-core 
> won't try to be matched here since it was not a complete mdev device.

The parent driver failing to set a type vs the parent driver failing to
register with a struct mdev_driver where id_table is not null are
different issues.  I agree that if a vendor driver was not updated for
this series that they'd never successfully create a device because the
mdev-core would reject it for not setting a class, but mdev_match() is
called for devices that might be created by other vendor drivers, so
loading a parent driver with a null id_table potentially breaks
matching for everyone.  Thanks,

Alex

Re: [PATCH V5 1/6] mdev: class id support

[Alex Williamson]

On Thu, 24 Oct 2019 13:46:36 -0600
Alex Williamson <alex.williamson@redhat.com> wrote:

> On Thu, 24 Oct 2019 11:27:36 +0800
> Jason Wang <jasowang@redhat.com> wrote:
> 
> > On 2019/10/24 上午5:42, Alex Williamson wrote:  
> > > On Wed, 23 Oct 2019 21:07:47 +0800
> > > Jason Wang <jasowang@redhat.com> wrote:
> > >    
> > >> Mdev bus only supports vfio driver right now, so it doesn't implement
> > >> match method. But in the future, we may add drivers other than vfio,
> > >> the first driver could be virtio-mdev. This means we need to add
> > >> device class id support in bus match method to pair the mdev device
> > >> and mdev driver correctly.
> > >>
> > >> So this patch adds id_table to mdev_driver and class_id for mdev
> > >> device with the match method for mdev bus.
> > >>
> > >> Signed-off-by: Jason Wang <jasowang@redhat.com>
> > >> ---
> > >>   .../driver-api/vfio-mediated-device.rst       |  5 +++++
> > >>   drivers/gpu/drm/i915/gvt/kvmgt.c              |  1 +
> > >>   drivers/s390/cio/vfio_ccw_ops.c               |  1 +
> > >>   drivers/s390/crypto/vfio_ap_ops.c             |  1 +
> > >>   drivers/vfio/mdev/mdev_core.c                 | 18 +++++++++++++++
> > >>   drivers/vfio/mdev/mdev_driver.c               | 22 +++++++++++++++++++
> > >>   drivers/vfio/mdev/mdev_private.h              |  1 +
> > >>   drivers/vfio/mdev/vfio_mdev.c                 |  6 +++++
> > >>   include/linux/mdev.h                          |  8 +++++++
> > >>   include/linux/mod_devicetable.h               |  8 +++++++
> > >>   samples/vfio-mdev/mbochs.c                    |  1 +
> > >>   samples/vfio-mdev/mdpy.c                      |  1 +
> > >>   samples/vfio-mdev/mtty.c                      |  1 +
> > >>   13 files changed, 74 insertions(+)
> > >>
> > >> diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
> > >> index 25eb7d5b834b..6709413bee29 100644
> > >> --- a/Documentation/driver-api/vfio-mediated-device.rst
> > >> +++ b/Documentation/driver-api/vfio-mediated-device.rst
> > >> @@ -102,12 +102,14 @@ structure to represent a mediated device's driver::
> > >>         * @probe: called when new device created
> > >>         * @remove: called when device removed
> > >>         * @driver: device driver structure
> > >> +      * @id_table: the ids serviced by this driver
> > >>         */
> > >>        struct mdev_driver {
> > >>   	     const char *name;
> > >>   	     int  (*probe)  (struct device *dev);
> > >>   	     void (*remove) (struct device *dev);
> > >>   	     struct device_driver    driver;
> > >> +	     const struct mdev_class_id *id_table;
> > >>        };
> > >>   
> > >>   A mediated bus driver for mdev should use this structure in the function calls
> > >> @@ -170,6 +172,9 @@ that a driver should use to unregister itself with the mdev core driver::
> > >>   
> > >>   	extern void mdev_unregister_device(struct device *dev);
> > >>   
> > >> +It is also required to specify the class_id in create() callback through::
> > >> +
> > >> +	int mdev_set_class(struct mdev_device *mdev, u16 id);
> > >>   
> > >>   Mediated Device Management Interface Through sysfs
> > >>   ==================================================
> > >> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> > >> index 343d79c1cb7e..6420f0dbd31b 100644
> > >> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> > >> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> > >> @@ -678,6 +678,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
> > >>   		     dev_name(mdev_dev(mdev)));
> > >>   	ret = 0;
> > >>   
> > >> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> > >>   out:
> > >>   	return ret;
> > >>   }
> > >> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
> > >> index f0d71ab77c50..cf2c013ae32f 100644
> > >> --- a/drivers/s390/cio/vfio_ccw_ops.c
> > >> +++ b/drivers/s390/cio/vfio_ccw_ops.c
> > >> @@ -129,6 +129,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
> > >>   			   private->sch->schid.ssid,
> > >>   			   private->sch->schid.sch_no);
> > >>   
> > >> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> > >>   	return 0;
> > >>   }
> > >>   
> > >> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> > >> index 5c0f53c6dde7..07c31070afeb 100644
> > >> --- a/drivers/s390/crypto/vfio_ap_ops.c
> > >> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> > >> @@ -343,6 +343,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
> > >>   	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
> > >>   	mutex_unlock(&matrix_dev->lock);
> > >>   
> > >> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
> > >>   	return 0;
> > >>   }
> > >>   
> > >> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> > >> index b558d4cfd082..3a9c52d71b4e 100644
> > >> --- a/drivers/vfio/mdev/mdev_core.c
> > >> +++ b/drivers/vfio/mdev/mdev_core.c
> > >> @@ -45,6 +45,16 @@ void mdev_set_drvdata(struct mdev_device *mdev, void *data)
> > >>   }
> > >>   EXPORT_SYMBOL(mdev_set_drvdata);
> > >>   
> > >> +/* Specify the class for the mdev device, this must be called during
> > >> + * create() callback.
> > >> + */
> > >> +void mdev_set_class(struct mdev_device *mdev, u16 id)
> > >> +{
> > >> +	WARN_ON(mdev->class_id);
> > >> +	mdev->class_id = id;
> > >> +}
> > >> +EXPORT_SYMBOL(mdev_set_class);
> > >> +
> > >>   struct device *mdev_dev(struct mdev_device *mdev)
> > >>   {
> > >>   	return &mdev->dev;
> > >> @@ -135,6 +145,7 @@ static int mdev_device_remove_cb(struct device *dev, void *data)
> > >>    * mdev_register_device : Register a device
> > >>    * @dev: device structure representing parent device.
> > >>    * @ops: Parent device operation structure to be registered.
> > >> + * @id: class id.
> > >>    *
> > >>    * Add device to list of registered parent devices.
> > >>    * Returns a negative value on error, otherwise 0.
> > >> @@ -324,6 +335,13 @@ int mdev_device_create(struct kobject *kobj,
> > >>   	if (ret)
> > >>   		goto ops_create_fail;
> > >>   
> > >> +	if (!mdev->class_id) {
> > >> +		ret = -EINVAL;
> > >> +		WARN(1, "class id must be specified for device %s\n",
> > >> +		     dev_name(dev));    
> > > Nit, dev_warn(dev, "mdev vendor driver failed to specify device class\n");    
> > 
> > 
> > Will fix.
> > 
> >   
> > >    
> > >> +		goto add_fail;
> > >> +	}
> > >> +
> > >>   	ret = device_add(&mdev->dev);
> > >>   	if (ret)
> > >>   		goto add_fail;
> > >> diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
> > >> index 0d3223aee20b..319d886ffaf7 100644
> > >> --- a/drivers/vfio/mdev/mdev_driver.c
> > >> +++ b/drivers/vfio/mdev/mdev_driver.c
> > >> @@ -69,8 +69,30 @@ static int mdev_remove(struct device *dev)
> > >>   	return 0;
> > >>   }
> > >>   
> > >> +static int mdev_match(struct device *dev, struct device_driver *drv)
> > >> +{
> > >> +	unsigned int i;
> > >> +	struct mdev_device *mdev = to_mdev_device(dev);
> > >> +	struct mdev_driver *mdrv = to_mdev_driver(drv);
> > >> +	const struct mdev_class_id *ids = mdrv->id_table;
> > >> +    
> > > Nit, as we start to allow new mdev bus drivers, mdev-core might want to
> > > protect itself from a NULL id_table, by either failing the
> > > mdev_register_driver() or failing the match here.  I think such a
> > > condition would segfault as written here, but clearly we don't have
> > > such external drivers yet.  Thanks,    
> > 
> > 
> > I'm not sure I get the point here. My understanding is that mdev-core 
> > won't try to be matched here since it was not a complete mdev device.  
> 
> The parent driver failing to set a type vs the parent driver failing to

Correction, the second half of this should be in reference to the mdev
bus driver.

> register with a struct mdev_driver where id_table is not null are
> different issues.  I agree that if a vendor driver was not updated for
> this series that they'd never successfully create a device because the
> mdev-core would reject it for not setting a class, but mdev_match() is
> called for devices that might be created by other vendor drivers, so
> loading a parent driver with a null id_table potentially breaks
> matching for everyone.  Thanks,

The point is still valid though, for example if vfio-mdev registered
with a null id_table it would break matching for virtio-mdev depending
on the order we iterate through drivers as we call mdev_match().
Thanks,

Alex

Re: [PATCH V5 1/6] mdev: class id support

[Jason Wang]

On 2019/10/25 上午4:13, Alex Williamson wrote:
> On Thu, 24 Oct 2019 13:46:36 -0600
> Alex Williamson <alex.williamson@redhat.com> wrote:
>
>> On Thu, 24 Oct 2019 11:27:36 +0800
>> Jason Wang <jasowang@redhat.com> wrote:
>>
>>> On 2019/10/24 上午5:42, Alex Williamson wrote:
>>>> On Wed, 23 Oct 2019 21:07:47 +0800
>>>> Jason Wang <jasowang@redhat.com> wrote:
>>>>     
>>>>> Mdev bus only supports vfio driver right now, so it doesn't implement
>>>>> match method. But in the future, we may add drivers other than vfio,
>>>>> the first driver could be virtio-mdev. This means we need to add
>>>>> device class id support in bus match method to pair the mdev device
>>>>> and mdev driver correctly.
>>>>>
>>>>> So this patch adds id_table to mdev_driver and class_id for mdev
>>>>> device with the match method for mdev bus.
>>>>>
>>>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>>>>> ---
>>>>>    .../driver-api/vfio-mediated-device.rst       |  5 +++++
>>>>>    drivers/gpu/drm/i915/gvt/kvmgt.c              |  1 +
>>>>>    drivers/s390/cio/vfio_ccw_ops.c               |  1 +
>>>>>    drivers/s390/crypto/vfio_ap_ops.c             |  1 +
>>>>>    drivers/vfio/mdev/mdev_core.c                 | 18 +++++++++++++++
>>>>>    drivers/vfio/mdev/mdev_driver.c               | 22 +++++++++++++++++++
>>>>>    drivers/vfio/mdev/mdev_private.h              |  1 +
>>>>>    drivers/vfio/mdev/vfio_mdev.c                 |  6 +++++
>>>>>    include/linux/mdev.h                          |  8 +++++++
>>>>>    include/linux/mod_devicetable.h               |  8 +++++++
>>>>>    samples/vfio-mdev/mbochs.c                    |  1 +
>>>>>    samples/vfio-mdev/mdpy.c                      |  1 +
>>>>>    samples/vfio-mdev/mtty.c                      |  1 +
>>>>>    13 files changed, 74 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
>>>>> index 25eb7d5b834b..6709413bee29 100644
>>>>> --- a/Documentation/driver-api/vfio-mediated-device.rst
>>>>> +++ b/Documentation/driver-api/vfio-mediated-device.rst
>>>>> @@ -102,12 +102,14 @@ structure to represent a mediated device's driver::
>>>>>          * @probe: called when new device created
>>>>>          * @remove: called when device removed
>>>>>          * @driver: device driver structure
>>>>> +      * @id_table: the ids serviced by this driver
>>>>>          */
>>>>>         struct mdev_driver {
>>>>>    	     const char *name;
>>>>>    	     int  (*probe)  (struct device *dev);
>>>>>    	     void (*remove) (struct device *dev);
>>>>>    	     struct device_driver    driver;
>>>>> +	     const struct mdev_class_id *id_table;
>>>>>         };
>>>>>    
>>>>>    A mediated bus driver for mdev should use this structure in the function calls
>>>>> @@ -170,6 +172,9 @@ that a driver should use to unregister itself with the mdev core driver::
>>>>>    
>>>>>    	extern void mdev_unregister_device(struct device *dev);
>>>>>    
>>>>> +It is also required to specify the class_id in create() callback through::
>>>>> +
>>>>> +	int mdev_set_class(struct mdev_device *mdev, u16 id);
>>>>>    
>>>>>    Mediated Device Management Interface Through sysfs
>>>>>    ==================================================
>>>>> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
>>>>> index 343d79c1cb7e..6420f0dbd31b 100644
>>>>> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
>>>>> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
>>>>> @@ -678,6 +678,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
>>>>>    		     dev_name(mdev_dev(mdev)));
>>>>>    	ret = 0;
>>>>>    
>>>>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>>>>    out:
>>>>>    	return ret;
>>>>>    }
>>>>> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
>>>>> index f0d71ab77c50..cf2c013ae32f 100644
>>>>> --- a/drivers/s390/cio/vfio_ccw_ops.c
>>>>> +++ b/drivers/s390/cio/vfio_ccw_ops.c
>>>>> @@ -129,6 +129,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>>>>>    			   private->sch->schid.ssid,
>>>>>    			   private->sch->schid.sch_no);
>>>>>    
>>>>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>>>>    	return 0;
>>>>>    }
>>>>>    
>>>>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
>>>>> index 5c0f53c6dde7..07c31070afeb 100644
>>>>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>>>>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>>>>> @@ -343,6 +343,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>>>>>    	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
>>>>>    	mutex_unlock(&matrix_dev->lock);
>>>>>    
>>>>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
>>>>>    	return 0;
>>>>>    }
>>>>>    
>>>>> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
>>>>> index b558d4cfd082..3a9c52d71b4e 100644
>>>>> --- a/drivers/vfio/mdev/mdev_core.c
>>>>> +++ b/drivers/vfio/mdev/mdev_core.c
>>>>> @@ -45,6 +45,16 @@ void mdev_set_drvdata(struct mdev_device *mdev, void *data)
>>>>>    }
>>>>>    EXPORT_SYMBOL(mdev_set_drvdata);
>>>>>    
>>>>> +/* Specify the class for the mdev device, this must be called during
>>>>> + * create() callback.
>>>>> + */
>>>>> +void mdev_set_class(struct mdev_device *mdev, u16 id)
>>>>> +{
>>>>> +	WARN_ON(mdev->class_id);
>>>>> +	mdev->class_id = id;
>>>>> +}
>>>>> +EXPORT_SYMBOL(mdev_set_class);
>>>>> +
>>>>>    struct device *mdev_dev(struct mdev_device *mdev)
>>>>>    {
>>>>>    	return &mdev->dev;
>>>>> @@ -135,6 +145,7 @@ static int mdev_device_remove_cb(struct device *dev, void *data)
>>>>>     * mdev_register_device : Register a device
>>>>>     * @dev: device structure representing parent device.
>>>>>     * @ops: Parent device operation structure to be registered.
>>>>> + * @id: class id.
>>>>>     *
>>>>>     * Add device to list of registered parent devices.
>>>>>     * Returns a negative value on error, otherwise 0.
>>>>> @@ -324,6 +335,13 @@ int mdev_device_create(struct kobject *kobj,
>>>>>    	if (ret)
>>>>>    		goto ops_create_fail;
>>>>>    
>>>>> +	if (!mdev->class_id) {
>>>>> +		ret = -EINVAL;
>>>>> +		WARN(1, "class id must be specified for device %s\n",
>>>>> +		     dev_name(dev));
>>>> Nit, dev_warn(dev, "mdev vendor driver failed to specify device class\n");
>>>
>>> Will fix.
>>>
>>>    
>>>>     
>>>>> +		goto add_fail;
>>>>> +	}
>>>>> +
>>>>>    	ret = device_add(&mdev->dev);
>>>>>    	if (ret)
>>>>>    		goto add_fail;
>>>>> diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
>>>>> index 0d3223aee20b..319d886ffaf7 100644
>>>>> --- a/drivers/vfio/mdev/mdev_driver.c
>>>>> +++ b/drivers/vfio/mdev/mdev_driver.c
>>>>> @@ -69,8 +69,30 @@ static int mdev_remove(struct device *dev)
>>>>>    	return 0;
>>>>>    }
>>>>>    
>>>>> +static int mdev_match(struct device *dev, struct device_driver *drv)
>>>>> +{
>>>>> +	unsigned int i;
>>>>> +	struct mdev_device *mdev = to_mdev_device(dev);
>>>>> +	struct mdev_driver *mdrv = to_mdev_driver(drv);
>>>>> +	const struct mdev_class_id *ids = mdrv->id_table;
>>>>> +
>>>> Nit, as we start to allow new mdev bus drivers, mdev-core might want to
>>>> protect itself from a NULL id_table, by either failing the
>>>> mdev_register_driver() or failing the match here.  I think such a
>>>> condition would segfault as written here, but clearly we don't have
>>>> such external drivers yet.  Thanks,
>>>
>>> I'm not sure I get the point here. My understanding is that mdev-core
>>> won't try to be matched here since it was not a complete mdev device.
>> The parent driver failing to set a type vs the parent driver failing to
> Correction, the second half of this should be in reference to the mdev
> bus driver.
>
>> register with a struct mdev_driver where id_table is not null are
>> different issues.  I agree that if a vendor driver was not updated for
>> this series that they'd never successfully create a device because the
>> mdev-core would reject it for not setting a class, but mdev_match() is
>> called for devices that might be created by other vendor drivers, so
>> loading a parent driver with a null id_table potentially breaks
>> matching for everyone.  Thanks,
> The point is still valid though, for example if vfio-mdev registered
> with a null id_table it would break matching for virtio-mdev depending
> on the order we iterate through drivers as we call mdev_match().
> Thanks,
>
> Alex


I see the point, so I can check the existence of id_table before trying 
to do the match here.

Thanks

[PATCH V5 2/6] modpost: add support for mdev class id

[Jason Wang]

Add support to parse mdev class id table.

Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vfio/mdev/vfio_mdev.c     |  2 ++
 scripts/mod/devicetable-offsets.c |  3 +++
 scripts/mod/file2alias.c          | 10 ++++++++++
 3 files changed, 15 insertions(+)

diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
index 7b24ee9cb8dd..cb701cd646f0 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -125,6 +125,8 @@ static const struct mdev_class_id id_table[] = {
 	{ 0 },
 };
 
+MODULE_DEVICE_TABLE(mdev, id_table);
+
 static struct mdev_driver vfio_mdev_driver = {
 	.name	= "vfio_mdev",
 	.probe	= vfio_mdev_probe,
diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index 054405b90ba4..6cbb1062488a 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_class_id);
+	DEVID_FIELD(mdev_class_id, id);
+
 	return 0;
 }
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index c91eba751804..d365dfe7c718 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -1335,6 +1335,15 @@ static int do_wmi_entry(const char *filename, void *symval, char *alias)
 	return 1;
 }
 
+/* looks like: "mdev:cN" */
+static int do_mdev_entry(const char *filename, void *symval, char *alias)
+{
+	DEF_FIELD(symval, mdev_class_id, id);
+
+	sprintf(alias, "mdev:c%02X", id);
+	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 +1416,7 @@ 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", SIZE_mdev_class_id, do_mdev_entry},
 };
 
 /* Create MODULE_ALIAS() statements.
-- 
2.19.1

Re: [PATCH V5 2/6] modpost: add support for mdev class id

[Alex Williamson]

On Wed, 23 Oct 2019 21:07:48 +0800
Jason Wang <jasowang@redhat.com> wrote:

> Add support to parse mdev class id table.
> 
> Reviewed-by: Parav Pandit <parav@mellanox.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  drivers/vfio/mdev/vfio_mdev.c     |  2 ++
>  scripts/mod/devicetable-offsets.c |  3 +++
>  scripts/mod/file2alias.c          | 10 ++++++++++
>  3 files changed, 15 insertions(+)
> 
> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
> index 7b24ee9cb8dd..cb701cd646f0 100644
> --- a/drivers/vfio/mdev/vfio_mdev.c
> +++ b/drivers/vfio/mdev/vfio_mdev.c
> @@ -125,6 +125,8 @@ static const struct mdev_class_id id_table[] = {
>  	{ 0 },
>  };
>  
> +MODULE_DEVICE_TABLE(mdev, id_table);
> +

Two questions, first we have:

#define MODULE_DEVICE_TABLE(type, name)                                 \
extern typeof(name) __mod_##type##__##name##_device_table               \
  __attribute__ ((unused, alias(__stringify(name))))

Therefore we're defining __mod_mdev__id_table_device_table with alias
id_table.  When the virtio mdev bus driver is added in 5/6 it uses the
same name value.  I see virtio types all register this way (virtio,
id_table), so I assume there's no conflict, but pci types mostly (not
entirely) seem to use unique names.  Is there a preference to one way
or the other or it simply doesn't matter?

>  static struct mdev_driver vfio_mdev_driver = {
>  	.name	= "vfio_mdev",
>  	.probe	= vfio_mdev_probe,
> diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
> index 054405b90ba4..6cbb1062488a 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_class_id);
> +	DEVID_FIELD(mdev_class_id, id);
> +
>  	return 0;
>  }
> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> index c91eba751804..d365dfe7c718 100644
> --- a/scripts/mod/file2alias.c
> +++ b/scripts/mod/file2alias.c
> @@ -1335,6 +1335,15 @@ static int do_wmi_entry(const char *filename, void *symval, char *alias)
>  	return 1;
>  }
>  
> +/* looks like: "mdev:cN" */
> +static int do_mdev_entry(const char *filename, void *symval, char *alias)
> +{
> +	DEF_FIELD(symval, mdev_class_id, id);
> +
> +	sprintf(alias, "mdev:c%02X", id);

A lot of entries call add_wildcard() here, should we?  Sorry for the
basic questions, I haven't played in this code.  Thanks,

Alex

> +	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 +1416,7 @@ 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", SIZE_mdev_class_id, do_mdev_entry},
>  };
>  
>  /* Create MODULE_ALIAS() statements.

Re: [PATCH V5 2/6] modpost: add support for mdev class id

[Jason Wang]

On 2019/10/24 上午5:42, Alex Williamson wrote:
> On Wed, 23 Oct 2019 21:07:48 +0800
> Jason Wang <jasowang@redhat.com> wrote:
>
>> Add support to parse mdev class id table.
>>
>> Reviewed-by: Parav Pandit <parav@mellanox.com>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>   drivers/vfio/mdev/vfio_mdev.c     |  2 ++
>>   scripts/mod/devicetable-offsets.c |  3 +++
>>   scripts/mod/file2alias.c          | 10 ++++++++++
>>   3 files changed, 15 insertions(+)
>>
>> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
>> index 7b24ee9cb8dd..cb701cd646f0 100644
>> --- a/drivers/vfio/mdev/vfio_mdev.c
>> +++ b/drivers/vfio/mdev/vfio_mdev.c
>> @@ -125,6 +125,8 @@ static const struct mdev_class_id id_table[] = {
>>   	{ 0 },
>>   };
>>   
>> +MODULE_DEVICE_TABLE(mdev, id_table);
>> +
> Two questions, first we have:
>
> #define MODULE_DEVICE_TABLE(type, name)                                 \
> extern typeof(name) __mod_##type##__##name##_device_table               \
>    __attribute__ ((unused, alias(__stringify(name))))
>
> Therefore we're defining __mod_mdev__id_table_device_table with alias
> id_table.  When the virtio mdev bus driver is added in 5/6 it uses the
> same name value.  I see virtio types all register this way (virtio,
> id_table), so I assume there's no conflict, but pci types mostly (not
> entirely) seem to use unique names.  Is there a preference to one way
> or the other or it simply doesn't matter?


It looks to me that those symbol were local, so it doesn't matter. But 
if you wish I can switch to use unique name.


>
>>   static struct mdev_driver vfio_mdev_driver = {
>>   	.name	= "vfio_mdev",
>>   	.probe	= vfio_mdev_probe,
>> diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
>> index 054405b90ba4..6cbb1062488a 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_class_id);
>> +	DEVID_FIELD(mdev_class_id, id);
>> +
>>   	return 0;
>>   }
>> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
>> index c91eba751804..d365dfe7c718 100644
>> --- a/scripts/mod/file2alias.c
>> +++ b/scripts/mod/file2alias.c
>> @@ -1335,6 +1335,15 @@ static int do_wmi_entry(const char *filename, void *symval, char *alias)
>>   	return 1;
>>   }
>>   
>> +/* looks like: "mdev:cN" */
>> +static int do_mdev_entry(const char *filename, void *symval, char *alias)
>> +{
>> +	DEF_FIELD(symval, mdev_class_id, id);
>> +
>> +	sprintf(alias, "mdev:c%02X", id);
> A lot of entries call add_wildcard() here, should we?  Sorry for the
> basic questions, I haven't played in this code.  Thanks,


It's really good question. My understanding is we won't have a module 
that can deal with all kinds of classes like CLASS_ID_ANY. So there's 
probably no need for the wildcard.

Thanks


>
> Alex
>
>> +	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 +1416,7 @@ 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", SIZE_mdev_class_id, do_mdev_entry},
>>   };
>>   
>>   /* Create MODULE_ALIAS() statements.

Re: [PATCH V5 2/6] modpost: add support for mdev class id

[Alex Williamson]

On Thu, 24 Oct 2019 11:31:04 +0800
Jason Wang <jasowang@redhat.com> wrote:

> On 2019/10/24 上午5:42, Alex Williamson wrote:
> > On Wed, 23 Oct 2019 21:07:48 +0800
> > Jason Wang <jasowang@redhat.com> wrote:
> >  
> >> Add support to parse mdev class id table.
> >>
> >> Reviewed-by: Parav Pandit <parav@mellanox.com>
> >> Signed-off-by: Jason Wang <jasowang@redhat.com>
> >> ---
> >>   drivers/vfio/mdev/vfio_mdev.c     |  2 ++
> >>   scripts/mod/devicetable-offsets.c |  3 +++
> >>   scripts/mod/file2alias.c          | 10 ++++++++++
> >>   3 files changed, 15 insertions(+)
> >>
> >> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
> >> index 7b24ee9cb8dd..cb701cd646f0 100644
> >> --- a/drivers/vfio/mdev/vfio_mdev.c
> >> +++ b/drivers/vfio/mdev/vfio_mdev.c
> >> @@ -125,6 +125,8 @@ static const struct mdev_class_id id_table[] = {
> >>   	{ 0 },
> >>   };
> >>   
> >> +MODULE_DEVICE_TABLE(mdev, id_table);
> >> +  
> > Two questions, first we have:
> >
> > #define MODULE_DEVICE_TABLE(type, name)                                 \
> > extern typeof(name) __mod_##type##__##name##_device_table               \
> >    __attribute__ ((unused, alias(__stringify(name))))
> >
> > Therefore we're defining __mod_mdev__id_table_device_table with alias
> > id_table.  When the virtio mdev bus driver is added in 5/6 it uses the
> > same name value.  I see virtio types all register this way (virtio,
> > id_table), so I assume there's no conflict, but pci types mostly (not
> > entirely) seem to use unique names.  Is there a preference to one way
> > or the other or it simply doesn't matter?  
> 
> 
> It looks to me that those symbol were local, so it doesn't matter. But 
> if you wish I can switch to use unique name.

I don't have a strong opinion, I'm just trying to make sure we're not
doing something obviously broken.

> >>   static struct mdev_driver vfio_mdev_driver = {
> >>   	.name	= "vfio_mdev",
> >>   	.probe	= vfio_mdev_probe,
> >> diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
> >> index 054405b90ba4..6cbb1062488a 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_class_id);
> >> +	DEVID_FIELD(mdev_class_id, id);
> >> +
> >>   	return 0;
> >>   }
> >> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> >> index c91eba751804..d365dfe7c718 100644
> >> --- a/scripts/mod/file2alias.c
> >> +++ b/scripts/mod/file2alias.c
> >> @@ -1335,6 +1335,15 @@ static int do_wmi_entry(const char *filename, void *symval, char *alias)
> >>   	return 1;
> >>   }
> >>   
> >> +/* looks like: "mdev:cN" */
> >> +static int do_mdev_entry(const char *filename, void *symval, char *alias)
> >> +{
> >> +	DEF_FIELD(symval, mdev_class_id, id);
> >> +
> >> +	sprintf(alias, "mdev:c%02X", id);  
> > A lot of entries call add_wildcard() here, should we?  Sorry for the
> > basic questions, I haven't played in this code.  Thanks,  
> 
> 
> It's really good question. My understanding is we won't have a module 
> that can deal with all kinds of classes like CLASS_ID_ANY. So there's 
> probably no need for the wildcard.

The comment for add_wildcard() indicates future extension, so it's hard
to know what we might need in the future until we do need it.  The
majority of modules.alias entries on my laptop (even if I exclude pci
aliases) end with a wildcard.  Thanks,

Alex

Re: [PATCH V5 2/6] modpost: add support for mdev class id

[Jason Wang]

On 2019/10/25 上午3:54, Alex Williamson wrote:
> On Thu, 24 Oct 2019 11:31:04 +0800
> Jason Wang <jasowang@redhat.com> wrote:
>
>> On 2019/10/24 上午5:42, Alex Williamson wrote:
>>> On Wed, 23 Oct 2019 21:07:48 +0800
>>> Jason Wang <jasowang@redhat.com> wrote:
>>>   
>>>> Add support to parse mdev class id table.
>>>>
>>>> Reviewed-by: Parav Pandit <parav@mellanox.com>
>>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>>>> ---
>>>>    drivers/vfio/mdev/vfio_mdev.c     |  2 ++
>>>>    scripts/mod/devicetable-offsets.c |  3 +++
>>>>    scripts/mod/file2alias.c          | 10 ++++++++++
>>>>    3 files changed, 15 insertions(+)
>>>>
>>>> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
>>>> index 7b24ee9cb8dd..cb701cd646f0 100644
>>>> --- a/drivers/vfio/mdev/vfio_mdev.c
>>>> +++ b/drivers/vfio/mdev/vfio_mdev.c
>>>> @@ -125,6 +125,8 @@ static const struct mdev_class_id id_table[] = {
>>>>    	{ 0 },
>>>>    };
>>>>    
>>>> +MODULE_DEVICE_TABLE(mdev, id_table);
>>>> +
>>> Two questions, first we have:
>>>
>>> #define MODULE_DEVICE_TABLE(type, name)                                 \
>>> extern typeof(name) __mod_##type##__##name##_device_table               \
>>>     __attribute__ ((unused, alias(__stringify(name))))
>>>
>>> Therefore we're defining __mod_mdev__id_table_device_table with alias
>>> id_table.  When the virtio mdev bus driver is added in 5/6 it uses the
>>> same name value.  I see virtio types all register this way (virtio,
>>> id_table), so I assume there's no conflict, but pci types mostly (not
>>> entirely) seem to use unique names.  Is there a preference to one way
>>> or the other or it simply doesn't matter?
>>
>> It looks to me that those symbol were local, so it doesn't matter. But
>> if you wish I can switch to use unique name.
> I don't have a strong opinion, I'm just trying to make sure we're not
> doing something obviously broken.


Yes, to be more safe I will switch to unique names here.


>
>>>>    static struct mdev_driver vfio_mdev_driver = {
>>>>    	.name	= "vfio_mdev",
>>>>    	.probe	= vfio_mdev_probe,
>>>> diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
>>>> index 054405b90ba4..6cbb1062488a 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_class_id);
>>>> +	DEVID_FIELD(mdev_class_id, id);
>>>> +
>>>>    	return 0;
>>>>    }
>>>> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
>>>> index c91eba751804..d365dfe7c718 100644
>>>> --- a/scripts/mod/file2alias.c
>>>> +++ b/scripts/mod/file2alias.c
>>>> @@ -1335,6 +1335,15 @@ static int do_wmi_entry(const char *filename, void *symval, char *alias)
>>>>    	return 1;
>>>>    }
>>>>    
>>>> +/* looks like: "mdev:cN" */
>>>> +static int do_mdev_entry(const char *filename, void *symval, char *alias)
>>>> +{
>>>> +	DEF_FIELD(symval, mdev_class_id, id);
>>>> +
>>>> +	sprintf(alias, "mdev:c%02X", id);
>>> A lot of entries call add_wildcard() here, should we?  Sorry for the
>>> basic questions, I haven't played in this code.  Thanks,
>>
>> It's really good question. My understanding is we won't have a module
>> that can deal with all kinds of classes like CLASS_ID_ANY. So there's
>> probably no need for the wildcard.
> The comment for add_wildcard() indicates future extension, so it's hard
> to know what we might need in the future until we do need it.  The
> majority of modules.alias entries on my laptop (even if I exclude pci
> aliases) end with a wildcard.  Thanks,


Yes, so I will add that for future extension.

Thanks


>
> Alex
>

[PATCH V5 3/6] mdev: introduce device specific ops

[Jason Wang]

Currently, except for the create and remove, the rest of
mdev_parent_ops is designed for vfio-mdev driver only and may not help
for kernel mdev driver. With the help of class id, this patch
introduces device specific callbacks inside mdev_device
structure. This allows different set of callback to be used by
vfio-mdev and virtio-mdev.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 .../driver-api/vfio-mediated-device.rst       | 35 +++++++++----
 MAINTAINERS                                   |  1 +
 drivers/gpu/drm/i915/gvt/kvmgt.c              | 18 ++++---
 drivers/s390/cio/vfio_ccw_ops.c               | 18 ++++---
 drivers/s390/crypto/vfio_ap_ops.c             | 14 +++--
 drivers/vfio/mdev/mdev_core.c                 | 25 ++++++++-
 drivers/vfio/mdev/mdev_private.h              |  5 ++
 drivers/vfio/mdev/vfio_mdev.c                 | 37 ++++++-------
 include/linux/mdev.h                          | 43 ++++-----------
 include/linux/vfio_mdev_ops.h                 | 52 +++++++++++++++++++
 samples/vfio-mdev/mbochs.c                    | 20 ++++---
 samples/vfio-mdev/mdpy.c                      | 20 ++++---
 samples/vfio-mdev/mtty.c                      | 18 ++++---
 13 files changed, 206 insertions(+), 100 deletions(-)
 create mode 100644 include/linux/vfio_mdev_ops.h

diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
index 6709413bee29..0d8f9e7d7983 100644
--- a/Documentation/driver-api/vfio-mediated-device.rst
+++ b/Documentation/driver-api/vfio-mediated-device.rst
@@ -152,15 +152,6 @@ callbacks per mdev parent device, per mdev type, or any other categorization.
 Vendor drivers are expected to be fully asynchronous in this respect or
 provide their own internal resource protection.)
 
-The callbacks in the mdev_parent_ops structure are as follows:
-
-* open: open callback of mediated device
-* close: close callback of mediated device
-* ioctl: ioctl callback of mediated device
-* read : read emulation callback
-* write: write emulation callback
-* mmap: mmap emulation callback
-
 A driver should use the mdev_parent_ops structure in the function call to
 register itself with the mdev core driver::
 
@@ -172,10 +163,34 @@ that a driver should use to unregister itself with the mdev core driver::
 
 	extern void mdev_unregister_device(struct device *dev);
 
-It is also required to specify the class_id in create() callback through::
+As multiple types of mediated devices may be supported, class id needs
+to be specified in the create callback(). This could be done
+explicitly for the device that does not use on mdev bus for its
+operation through:
 
 	int mdev_set_class(struct mdev_device *mdev, u16 id);
 
+For the device that uses on the mdev bus for its operation, the class
+should provide helper function to set class id and device specific
+ops. E.g for vfio-mdev devices, the function to be called is::
+
+	int mdev_set_vfio_ops(struct mdev_device *mdev,
+                              const struct vfio_mdev_ops *vfio_ops);
+
+The class id (set by this function to MDEV_CLASS_ID_VFIO) is used to
+match a device with an mdev driver via its id table. The device
+specific callbacks (specified in *vfio_ops) are obtainable via
+mdev_get_vfio_ops() (for use by the mdev bus driver). A vfio-mdev
+device (class id MDEV_CLASS_ID_VFIO) uses the following
+device-specific ops:
+
+* open: open callback of vfio mediated device
+* close: close callback of vfio mediated device
+* ioctl: ioctl callback of vfio mediated device
+* read : read emulation callback
+* write: write emulation callback
+* mmap: mmap emulation callback
+
 Mediated Device Management Interface Through sysfs
 ==================================================
 
diff --git a/MAINTAINERS b/MAINTAINERS
index e51a68bf8ca8..9e10ae9c2b4d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17121,6 +17121,7 @@ S:	Maintained
 F:	Documentation/driver-api/vfio-mediated-device.rst
 F:	drivers/vfio/mdev/
 F:	include/linux/mdev.h
+F:	include/linux/vfio_mdev_ops.h
 F:	samples/vfio-mdev/
 
 VFIO PLATFORM DRIVER
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 6420f0dbd31b..c2b7f9dbe4d1 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -42,6 +42,7 @@
 #include <linux/kvm_host.h>
 #include <linux/vfio.h>
 #include <linux/mdev.h>
+#include <linux/vfio_mdev_ops.h>
 #include <linux/debugfs.h>
 
 #include <linux/nospec.h>
@@ -643,6 +644,8 @@ static void kvmgt_put_vfio_device(void *vgpu)
 	vfio_device_put(((struct intel_vgpu *)vgpu)->vdev.vfio_device);
 }
 
+static const struct vfio_mdev_device_ops intel_vfio_vgpu_dev_ops;
+
 static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
 {
 	struct intel_vgpu *vgpu = NULL;
@@ -678,7 +681,7 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
 		     dev_name(mdev_dev(mdev)));
 	ret = 0;
 
-	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
+	mdev_set_vfio_ops(mdev, &intel_vfio_vgpu_dev_ops);
 out:
 	return ret;
 }
@@ -1599,20 +1602,21 @@ static const struct attribute_group *intel_vgpu_groups[] = {
 	NULL,
 };
 
-static struct mdev_parent_ops intel_vgpu_ops = {
-	.mdev_attr_groups       = intel_vgpu_groups,
-	.create			= intel_vgpu_create,
-	.remove			= intel_vgpu_remove,
-
+static const struct vfio_mdev_device_ops intel_vfio_vgpu_dev_ops = {
 	.open			= intel_vgpu_open,
 	.release		= intel_vgpu_release,
-
 	.read			= intel_vgpu_read,
 	.write			= intel_vgpu_write,
 	.mmap			= intel_vgpu_mmap,
 	.ioctl			= intel_vgpu_ioctl,
 };
 
+static struct mdev_parent_ops intel_vgpu_ops = {
+	.mdev_attr_groups       = intel_vgpu_groups,
+	.create			= intel_vgpu_create,
+	.remove			= intel_vgpu_remove,
+};
+
 static int kvmgt_host_init(struct device *dev, void *gvt, const void *ops)
 {
 	struct attribute **kvm_type_attrs;
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index cf2c013ae32f..c36e6ca9ee65 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -12,6 +12,7 @@
 
 #include <linux/vfio.h>
 #include <linux/mdev.h>
+#include <linux/vfio_mdev_ops.h>
 #include <linux/nospec.h>
 #include <linux/slab.h>
 
@@ -110,6 +111,8 @@ static struct attribute_group *mdev_type_groups[] = {
 	NULL,
 };
 
+static const struct vfio_mdev_device_ops vfio_mdev_ops;
+
 static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
 {
 	struct vfio_ccw_private *private =
@@ -129,7 +132,7 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
 			   private->sch->schid.ssid,
 			   private->sch->schid.sch_no);
 
-	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
+	mdev_set_vfio_ops(mdev, &vfio_mdev_ops);
 	return 0;
 }
 
@@ -575,11 +578,7 @@ static ssize_t vfio_ccw_mdev_ioctl(struct mdev_device *mdev,
 	}
 }
 
-static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
-	.owner			= THIS_MODULE,
-	.supported_type_groups  = mdev_type_groups,
-	.create			= vfio_ccw_mdev_create,
-	.remove			= vfio_ccw_mdev_remove,
+static const struct vfio_mdev_device_ops vfio_mdev_ops = {
 	.open			= vfio_ccw_mdev_open,
 	.release		= vfio_ccw_mdev_release,
 	.read			= vfio_ccw_mdev_read,
@@ -587,6 +586,13 @@ static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
 	.ioctl			= vfio_ccw_mdev_ioctl,
 };
 
+static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
+	.owner			= THIS_MODULE,
+	.supported_type_groups  = mdev_type_groups,
+	.create			= vfio_ccw_mdev_create,
+	.remove			= vfio_ccw_mdev_remove,
+};
+
 int vfio_ccw_mdev_reg(struct subchannel *sch)
 {
 	return mdev_register_device(&sch->dev, &vfio_ccw_mdev_ops);
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 07c31070afeb..ed68d4f7c0a9 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -16,6 +16,7 @@
 #include <linux/bitops.h>
 #include <linux/kvm_host.h>
 #include <linux/module.h>
+#include <linux/vfio_mdev_ops.h>
 #include <asm/kvm.h>
 #include <asm/zcrypt.h>
 
@@ -321,6 +322,8 @@ static void vfio_ap_matrix_init(struct ap_config_info *info,
 	matrix->adm_max = info->apxa ? info->Nd : 15;
 }
 
+static const struct vfio_mdev_device_ops vfio_mdev_ops;
+
 static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
 {
 	struct ap_matrix_mdev *matrix_mdev;
@@ -343,7 +346,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
 	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
 	mutex_unlock(&matrix_dev->lock);
 
-	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
+	mdev_set_vfio_ops(mdev, &vfio_mdev_ops);
 	return 0;
 }
 
@@ -1281,15 +1284,18 @@ static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev,
 	return ret;
 }
 
+static const struct vfio_mdev_device_ops vfio_mdev_ops = {
+	.open			= vfio_ap_mdev_open,
+	.release		= vfio_ap_mdev_release,
+	.ioctl			= vfio_ap_mdev_ioctl,
+};
+
 static const struct mdev_parent_ops vfio_ap_matrix_ops = {
 	.owner			= THIS_MODULE,
 	.supported_type_groups	= vfio_ap_mdev_type_groups,
 	.mdev_attr_groups	= vfio_ap_mdev_attr_groups,
 	.create			= vfio_ap_mdev_create,
 	.remove			= vfio_ap_mdev_remove,
-	.open			= vfio_ap_mdev_open,
-	.release		= vfio_ap_mdev_release,
-	.ioctl			= vfio_ap_mdev_ioctl,
 };
 
 int vfio_ap_mdev_register(void)
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 3a9c52d71b4e..555bd61d8c38 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -45,9 +45,10 @@ void mdev_set_drvdata(struct mdev_device *mdev, void *data)
 }
 EXPORT_SYMBOL(mdev_set_drvdata);
 
+
 /* Specify the class for the mdev device, this must be called during
- * create() callback.
- */
+ * create() callback explicitly or implicity through the helpers
+ * provided by each class. */
 void mdev_set_class(struct mdev_device *mdev, u16 id)
 {
 	WARN_ON(mdev->class_id);
@@ -55,6 +56,26 @@ void mdev_set_class(struct mdev_device *mdev, u16 id)
 }
 EXPORT_SYMBOL(mdev_set_class);
 
+/* Specify the mdev device to be a VFIO mdev device, and set VFIO
+ * device ops for it. This must be called from the create() callback
+ * for VFIO mdev device.
+ */
+void mdev_set_vfio_ops(struct mdev_device *mdev,
+		       const struct vfio_mdev_device_ops *vfio_ops)
+{
+	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
+	mdev->vfio_ops = vfio_ops;
+}
+EXPORT_SYMBOL(mdev_set_vfio_ops);
+
+/* Get the VFIO device ops for the mdev device. */
+const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev)
+{
+	WARN_ON(mdev->class_id != MDEV_CLASS_ID_VFIO);
+	return mdev->vfio_ops;
+}
+EXPORT_SYMBOL(mdev_get_vfio_ops);
+
 struct device *mdev_dev(struct mdev_device *mdev)
 {
 	return &mdev->dev;
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index c65f436c1869..0770410ded2a 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -10,6 +10,8 @@
 #ifndef MDEV_PRIVATE_H
 #define MDEV_PRIVATE_H
 
+#include <linux/vfio_mdev_ops.h>
+
 int  mdev_bus_register(void);
 void mdev_bus_unregister(void);
 
@@ -34,6 +36,9 @@ struct mdev_device {
 	struct device *iommu_device;
 	bool active;
 	u16 class_id;
+	union {
+		const struct vfio_mdev_device_ops *vfio_ops;
+	};
 };
 
 #define to_mdev_device(dev)	container_of(dev, struct mdev_device, dev)
diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
index cb701cd646f0..d5ede5f0544e 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -14,6 +14,7 @@
 #include <linux/slab.h>
 #include <linux/vfio.h>
 #include <linux/mdev.h>
+#include <linux/vfio_mdev_ops.h>
 
 #include "mdev_private.h"
 
@@ -24,16 +25,16 @@
 static int vfio_mdev_open(void *device_data)
 {
 	struct mdev_device *mdev = device_data;
-	struct mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_device_ops *ops = mdev_get_vfio_ops(mdev);
 	int ret;
 
-	if (unlikely(!parent->ops->open))
+	if (unlikely(!ops->open))
 		return -EINVAL;
 
 	if (!try_module_get(THIS_MODULE))
 		return -ENODEV;
 
-	ret = parent->ops->open(mdev);
+	ret = ops->open(mdev);
 	if (ret)
 		module_put(THIS_MODULE);
 
@@ -43,10 +44,10 @@ static int vfio_mdev_open(void *device_data)
 static void vfio_mdev_release(void *device_data)
 {
 	struct mdev_device *mdev = device_data;
-	struct mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_device_ops *ops = mdev_get_vfio_ops(mdev);
 
-	if (likely(parent->ops->release))
-		parent->ops->release(mdev);
+	if (likely(ops->release))
+		ops->release(mdev);
 
 	module_put(THIS_MODULE);
 }
@@ -55,47 +56,47 @@ static long vfio_mdev_unlocked_ioctl(void *device_data,
 				     unsigned int cmd, unsigned long arg)
 {
 	struct mdev_device *mdev = device_data;
-	struct mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_device_ops *ops = mdev_get_vfio_ops(mdev);
 
-	if (unlikely(!parent->ops->ioctl))
+	if (unlikely(!ops->ioctl))
 		return -EINVAL;
 
-	return parent->ops->ioctl(mdev, cmd, arg);
+	return 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 mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_device_ops *ops = mdev_get_vfio_ops(mdev);
 
-	if (unlikely(!parent->ops->read))
+	if (unlikely(!ops->read))
 		return -EINVAL;
 
-	return parent->ops->read(mdev, buf, count, ppos);
+	return 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 mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_device_ops *ops = mdev_get_vfio_ops(mdev);
 
-	if (unlikely(!parent->ops->write))
+	if (unlikely(!ops->write))
 		return -EINVAL;
 
-	return parent->ops->write(mdev, buf, count, ppos);
+	return 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 mdev_parent *parent = mdev->parent;
+	const struct vfio_mdev_device_ops *ops = mdev_get_vfio_ops(mdev);
 
-	if (unlikely(!parent->ops->mmap))
+	if (unlikely(!ops->mmap))
 		return -EINVAL;
 
-	return parent->ops->mmap(mdev, vma);
+	return ops->mmap(mdev, vma);
 }
 
 static const struct vfio_device_ops vfio_mdev_dev_ops = {
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index 78b69d09eb54..4625f1a11014 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -10,7 +10,13 @@
 #ifndef MDEV_H
 #define MDEV_H
 
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/mdev.h>
+#include <uapi/linux/uuid.h>
+
 struct mdev_device;
+struct vfio_mdev_device_ops;
 
 /*
  * Called by the parent device driver to set the device which represents
@@ -48,30 +54,7 @@ struct device *mdev_get_iommu_device(struct device *dev);
  *			@mdev: mdev_device device structure which is being
  *			       destroyed
  *			Returns integer: success (0) or error (< 0)
- * @open:		Open mediated device.
- *			@mdev: mediated device.
- *			Returns integer: success (0) or error (< 0)
- * @release:		release mediated device
- *			@mdev: mediated device.
- * @read:		Read emulation callback
- *			@mdev: mediated device structure
- *			@buf: read buffer
- *			@count: number of bytes to read
- *			@ppos: address.
- *			Retuns number on bytes read on success or error.
- * @write:		Write emulation callback
- *			@mdev: mediated device structure
- *			@buf: write buffer
- *			@count: number of bytes to be written
- *			@ppos: address.
- *			Retuns number on bytes written on success or error.
- * @ioctl:		IOCTL callback
- *			@mdev: mediated device structure
- *			@cmd: ioctl command
- *			@arg: arguments to ioctl
- * @mmap:		mmap callback
- *			@mdev: mediated device structure
- *			@vma: vma structure
+ *
  * Parent device that support mediated device should be registered with mdev
  * module with mdev_parent_ops structure.
  **/
@@ -83,15 +66,6 @@ struct mdev_parent_ops {
 
 	int     (*create)(struct kobject *kobj, struct mdev_device *mdev);
 	int     (*remove)(struct mdev_device *mdev);
-	int     (*open)(struct mdev_device *mdev);
-	void    (*release)(struct mdev_device *mdev);
-	ssize_t (*read)(struct mdev_device *mdev, char __user *buf,
-			size_t count, loff_t *ppos);
-	ssize_t (*write)(struct mdev_device *mdev, const char __user *buf,
-			 size_t count, loff_t *ppos);
-	long	(*ioctl)(struct mdev_device *mdev, unsigned int cmd,
-			 unsigned long arg);
-	int	(*mmap)(struct mdev_device *mdev, struct vm_area_struct *vma);
 };
 
 /* interface for exporting mdev supported type attributes */
@@ -135,6 +109,9 @@ void *mdev_get_drvdata(struct mdev_device *mdev);
 void mdev_set_drvdata(struct mdev_device *mdev, void *data);
 const guid_t *mdev_uuid(struct mdev_device *mdev);
 void mdev_set_class(struct mdev_device *mdev, u16 id);
+void mdev_set_vfio_ops(struct mdev_device *mdev,
+		       const struct vfio_mdev_device_ops *vfio_ops);
+const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev);
 
 extern struct bus_type mdev_bus_type;
 
diff --git a/include/linux/vfio_mdev_ops.h b/include/linux/vfio_mdev_ops.h
new file mode 100644
index 000000000000..3907c5371c2b
--- /dev/null
+++ b/include/linux/vfio_mdev_ops.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * VFIO Mediated device definition
+ */
+
+#ifndef VFIO_MDEV_H
+#define VFIO_MDEV_H
+
+#include <linux/mdev.h>
+
+/**
+ * struct vfio_mdev_device_ops - Structure to be registered for each
+ * mdev device to register the device to vfio-mdev module.
+ *
+ * @open:		Open mediated device.
+ *			@mdev: mediated device.
+ *			Returns integer: success (0) or error (< 0)
+ * @release:		release mediated device
+ *			@mdev: mediated device.
+ * @read:		Read emulation callback
+ *			@mdev: mediated device structure
+ *			@buf: read buffer
+ *			@count: number of bytes to read
+ *			@ppos: address.
+ *			Retuns number on bytes read on success or error.
+ * @write:		Write emulation callback
+ *			@mdev: mediated device structure
+ *			@buf: write buffer
+ *			@count: number of bytes to be written
+ *			@ppos: address.
+ *			Retuns number on bytes written on success or error.
+ * @ioctl:		IOCTL callback
+ *			@mdev: mediated device structure
+ *			@cmd: ioctl command
+ *			@arg: arguments to ioctl
+ * @mmap:		mmap callback
+ *			@mdev: mediated device structure
+ *			@vma: vma structure
+ */
+struct vfio_mdev_device_ops {
+	int     (*open)(struct mdev_device *mdev);
+	void    (*release)(struct mdev_device *mdev);
+	ssize_t (*read)(struct mdev_device *mdev, char __user *buf,
+			size_t count, loff_t *ppos);
+	ssize_t (*write)(struct mdev_device *mdev, const char __user *buf,
+			 size_t count, loff_t *ppos);
+	long	(*ioctl)(struct mdev_device *mdev, unsigned int cmd,
+			 unsigned long arg);
+	int	(*mmap)(struct mdev_device *mdev, struct vm_area_struct *vma);
+};
+
+#endif
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index 115bc5074656..1afec20bf0c5 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -30,6 +30,7 @@
 #include <linux/iommu.h>
 #include <linux/sysfs.h>
 #include <linux/mdev.h>
+#include <linux/vfio_mdev_ops.h>
 #include <linux/pci.h>
 #include <linux/dma-buf.h>
 #include <linux/highmem.h>
@@ -516,6 +517,8 @@ static int mbochs_reset(struct mdev_device *mdev)
 	return 0;
 }
 
+static const struct vfio_mdev_device_ops vfio_mdev_ops;
+
 static int mbochs_create(struct kobject *kobj, struct mdev_device *mdev)
 {
 	const struct mbochs_type *type = mbochs_find_type(kobj);
@@ -561,7 +564,7 @@ static int mbochs_create(struct kobject *kobj, struct mdev_device *mdev)
 	mbochs_reset(mdev);
 
 	mbochs_used_mbytes += type->mbytes;
-	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
+	mdev_set_vfio_ops(mdev, &vfio_mdev_ops);
 	return 0;
 
 err_mem:
@@ -1419,12 +1422,7 @@ static struct attribute_group *mdev_type_groups[] = {
 	NULL,
 };
 
-static const struct mdev_parent_ops mdev_fops = {
-	.owner			= THIS_MODULE,
-	.mdev_attr_groups	= mdev_dev_groups,
-	.supported_type_groups	= mdev_type_groups,
-	.create			= mbochs_create,
-	.remove			= mbochs_remove,
+static const struct vfio_mdev_device_ops vfio_mdev_ops = {
 	.open			= mbochs_open,
 	.release		= mbochs_close,
 	.read			= mbochs_read,
@@ -1433,6 +1431,14 @@ static const struct mdev_parent_ops mdev_fops = {
 	.mmap			= mbochs_mmap,
 };
 
+static const struct mdev_parent_ops mdev_fops = {
+	.owner			= THIS_MODULE,
+	.mdev_attr_groups	= mdev_dev_groups,
+	.supported_type_groups	= mdev_type_groups,
+	.create			= mbochs_create,
+	.remove			= mbochs_remove,
+};
+
 static const struct file_operations vd_fops = {
 	.owner		= THIS_MODULE,
 };
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index 665614574d50..d571fb65f50f 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -26,6 +26,7 @@
 #include <linux/iommu.h>
 #include <linux/sysfs.h>
 #include <linux/mdev.h>
+#include <linux/vfio_mdev_ops.h>
 #include <linux/pci.h>
 #include <drm/drm_fourcc.h>
 #include "mdpy-defs.h"
@@ -226,6 +227,8 @@ static int mdpy_reset(struct mdev_device *mdev)
 	return 0;
 }
 
+static const struct vfio_mdev_device_ops vfio_mdev_ops;
+
 static int mdpy_create(struct kobject *kobj, struct mdev_device *mdev)
 {
 	const struct mdpy_type *type = mdpy_find_type(kobj);
@@ -269,7 +272,7 @@ static int mdpy_create(struct kobject *kobj, struct mdev_device *mdev)
 	mdpy_reset(mdev);
 
 	mdpy_count++;
-	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
+	mdev_set_vfio_ops(mdev, &vfio_mdev_ops);
 	return 0;
 }
 
@@ -726,12 +729,7 @@ static struct attribute_group *mdev_type_groups[] = {
 	NULL,
 };
 
-static const struct mdev_parent_ops mdev_fops = {
-	.owner			= THIS_MODULE,
-	.mdev_attr_groups	= mdev_dev_groups,
-	.supported_type_groups	= mdev_type_groups,
-	.create			= mdpy_create,
-	.remove			= mdpy_remove,
+static const struct vfio_mdev_device_ops vfio_mdev_ops = {
 	.open			= mdpy_open,
 	.release		= mdpy_close,
 	.read			= mdpy_read,
@@ -740,6 +738,14 @@ static const struct mdev_parent_ops mdev_fops = {
 	.mmap			= mdpy_mmap,
 };
 
+static const struct mdev_parent_ops mdev_fops = {
+	.owner			= THIS_MODULE,
+	.mdev_attr_groups	= mdev_dev_groups,
+	.supported_type_groups	= mdev_type_groups,
+	.create			= mdpy_create,
+	.remove			= mdpy_remove,
+};
+
 static const struct file_operations vd_fops = {
 	.owner		= THIS_MODULE,
 };
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 90da12ff7fd9..4048b242c636 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -27,6 +27,7 @@
 #include <linux/ctype.h>
 #include <linux/file.h>
 #include <linux/mdev.h>
+#include <linux/vfio_mdev_ops.h>
 #include <linux/pci.h>
 #include <linux/serial.h>
 #include <uapi/linux/serial_reg.h>
@@ -708,6 +709,8 @@ static ssize_t mdev_access(struct mdev_device *mdev, u8 *buf, size_t count,
 	return ret;
 }
 
+static const struct vfio_mdev_device_ops vfio_dev_ops;
+
 static int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
 {
 	struct mdev_state *mdev_state;
@@ -755,7 +758,7 @@ static int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
 	list_add(&mdev_state->next, &mdev_devices_list);
 	mutex_unlock(&mdev_list_lock);
 
-	mdev_set_class(mdev, MDEV_CLASS_ID_VFIO);
+	mdev_set_vfio_ops(mdev, &vfio_dev_ops);
 	return 0;
 }
 
@@ -1388,6 +1391,14 @@ static struct attribute_group *mdev_type_groups[] = {
 	NULL,
 };
 
+static const struct vfio_mdev_device_ops vfio_dev_ops = {
+	.open		= mtty_open,
+	.release	= mtty_close,
+	.read		= mtty_read,
+	.write		= mtty_write,
+	.ioctl		= mtty_ioctl,
+};
+
 static const struct mdev_parent_ops mdev_fops = {
 	.owner                  = THIS_MODULE,
 	.dev_attr_groups        = mtty_dev_groups,
@@ -1395,11 +1406,6 @@ static const struct mdev_parent_ops mdev_fops = {
 	.supported_type_groups  = mdev_type_groups,
 	.create                 = mtty_create,
 	.remove			= mtty_remove,
-	.open                   = mtty_open,
-	.release                = mtty_close,
-	.read                   = mtty_read,
-	.write                  = mtty_write,
-	.ioctl		        = mtty_ioctl,
 };
 
 static void mtty_device_release(struct device *dev)
-- 
2.19.1

[PATCH V5 4/6] mdev: introduce virtio device and its device ops

[Jason Wang]

This patch implements basic support for mdev driver that supports
virtio transport for kernel virtio driver.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/vfio/mdev/mdev_core.c    |  20 ++++
 drivers/vfio/mdev/mdev_private.h |   2 +
 include/linux/mdev.h             |   6 ++
 include/linux/virtio_mdev_ops.h  | 159 +++++++++++++++++++++++++++++++
 4 files changed, 187 insertions(+)
 create mode 100644 include/linux/virtio_mdev_ops.h

diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 555bd61d8c38..9b00c3513120 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -76,6 +76,26 @@ const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev)
 }
 EXPORT_SYMBOL(mdev_get_vfio_ops);
 
+/* Specify the virtio device ops for the mdev device, this
+ * must be called during create() callback for virtio mdev device.
+ */
+void mdev_set_virtio_ops(struct mdev_device *mdev,
+			 const struct virtio_mdev_device_ops *virtio_ops)
+{
+	mdev_set_class(mdev, MDEV_CLASS_ID_VIRTIO);
+	mdev->virtio_ops = virtio_ops;
+}
+EXPORT_SYMBOL(mdev_set_virtio_ops);
+
+/* Get the virtio device ops for the mdev device. */
+const struct virtio_mdev_device_ops *
+mdev_get_virtio_ops(struct mdev_device *mdev)
+{
+	WARN_ON(mdev->class_id != MDEV_CLASS_ID_VIRTIO);
+	return mdev->virtio_ops;
+}
+EXPORT_SYMBOL(mdev_get_virtio_ops);
+
 struct device *mdev_dev(struct mdev_device *mdev)
 {
 	return &mdev->dev;
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index 0770410ded2a..7b47890c34e7 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -11,6 +11,7 @@
 #define MDEV_PRIVATE_H
 
 #include <linux/vfio_mdev_ops.h>
+#include <linux/virtio_mdev_ops.h>
 
 int  mdev_bus_register(void);
 void mdev_bus_unregister(void);
@@ -38,6 +39,7 @@ struct mdev_device {
 	u16 class_id;
 	union {
 		const struct vfio_mdev_device_ops *vfio_ops;
+		const struct virtio_mdev_device_ops *virtio_ops;
 	};
 };
 
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index 4625f1a11014..9b69b0bbebfd 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -17,6 +17,7 @@
 
 struct mdev_device;
 struct vfio_mdev_device_ops;
+struct virtio_mdev_device_ops;
 
 /*
  * Called by the parent device driver to set the device which represents
@@ -112,6 +113,10 @@ void mdev_set_class(struct mdev_device *mdev, u16 id);
 void mdev_set_vfio_ops(struct mdev_device *mdev,
 		       const struct vfio_mdev_device_ops *vfio_ops);
 const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev);
+void mdev_set_virtio_ops(struct mdev_device *mdev,
+			 const struct virtio_mdev_device_ops *virtio_ops);
+const struct virtio_mdev_device_ops *
+mdev_get_virtio_ops(struct mdev_device *mdev);
 
 extern struct bus_type mdev_bus_type;
 
@@ -127,6 +132,7 @@ struct mdev_device *mdev_from_dev(struct device *dev);
 
 enum {
 	MDEV_CLASS_ID_VFIO = 1,
+	MDEV_CLASS_ID_VIRTIO = 2,
 	/* New entries must be added here */
 };
 
diff --git a/include/linux/virtio_mdev_ops.h b/include/linux/virtio_mdev_ops.h
new file mode 100644
index 000000000000..d417b41f2845
--- /dev/null
+++ b/include/linux/virtio_mdev_ops.h
@@ -0,0 +1,159 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Virtio mediated device driver
+ *
+ * Copyright 2019, Red Hat Corp.
+ *     Author: Jason Wang <jasowang@redhat.com>
+ */
+#ifndef _LINUX_VIRTIO_MDEV_H
+#define _LINUX_VIRTIO_MDEV_H
+
+#include <linux/interrupt.h>
+#include <linux/mdev.h>
+#include <uapi/linux/vhost.h>
+
+#define VIRTIO_MDEV_DEVICE_API_STRING		"virtio-mdev"
+#define VIRTIO_MDEV_F_VERSION_1 0x1
+
+struct virtio_mdev_callback {
+	irqreturn_t (*callback)(void *data);
+	void *private;
+};
+
+/**
+ * struct vfio_mdev_device_ops - Structure to be registered for each
+ * mdev device to register the device for virtio/vhost drivers.
+ *
+ * The device ops that is supported by VIRTIO_MDEV_F_VERSION_1, the
+ * callbacks are mandatory unless explicity 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
+ * @get_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_mdev_features:		Get a set of bits that demonstrate
+ *				thecapability of the mdev device. New
+ *				features bits must be added when
+ *				introducing new device ops.
+ *				@mdev: mediated device
+ *				Returns the mdev features (API) support by
+ *				the device.
+ * @get_generation:		Get device config generaton (optionally)
+ *				@mdev: mediated device
+ *				Returns u32: device generation
+ */
+struct virtio_mdev_device_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);
+
+	/* Virtio 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);
+
+	/* Mdev device ops */
+	u64 (*get_mdev_features)(struct mdev_device *mdev);
+};
+
+void mdev_set_virtio_ops(struct mdev_device *mdev,
+			 const struct virtio_mdev_device_ops *virtio_ops);
+
+#endif
-- 
2.19.1

Re: [PATCH V5 4/6] mdev: introduce virtio device and its device ops

[Alex Williamson]

On Wed, 23 Oct 2019 21:07:50 +0800
Jason Wang <jasowang@redhat.com> wrote:

> This patch implements basic support for mdev driver that supports
> virtio transport for kernel virtio driver.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  drivers/vfio/mdev/mdev_core.c    |  20 ++++
>  drivers/vfio/mdev/mdev_private.h |   2 +
>  include/linux/mdev.h             |   6 ++
>  include/linux/virtio_mdev_ops.h  | 159 +++++++++++++++++++++++++++++++
>  4 files changed, 187 insertions(+)
>  create mode 100644 include/linux/virtio_mdev_ops.h
> 
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index 555bd61d8c38..9b00c3513120 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -76,6 +76,26 @@ const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev)
>  }
>  EXPORT_SYMBOL(mdev_get_vfio_ops);
>  
> +/* Specify the virtio device ops for the mdev device, this
> + * must be called during create() callback for virtio mdev device.
> + */
> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> +			 const struct virtio_mdev_device_ops *virtio_ops)
> +{
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VIRTIO);
> +	mdev->virtio_ops = virtio_ops;
> +}
> +EXPORT_SYMBOL(mdev_set_virtio_ops);
> +
> +/* Get the virtio device ops for the mdev device. */
> +const struct virtio_mdev_device_ops *
> +mdev_get_virtio_ops(struct mdev_device *mdev)
> +{
> +	WARN_ON(mdev->class_id != MDEV_CLASS_ID_VIRTIO);
> +	return mdev->virtio_ops;
> +}
> +EXPORT_SYMBOL(mdev_get_virtio_ops);
> +
>  struct device *mdev_dev(struct mdev_device *mdev)
>  {
>  	return &mdev->dev;
> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
> index 0770410ded2a..7b47890c34e7 100644
> --- a/drivers/vfio/mdev/mdev_private.h
> +++ b/drivers/vfio/mdev/mdev_private.h
> @@ -11,6 +11,7 @@
>  #define MDEV_PRIVATE_H
>  
>  #include <linux/vfio_mdev_ops.h>
> +#include <linux/virtio_mdev_ops.h>
>  
>  int  mdev_bus_register(void);
>  void mdev_bus_unregister(void);
> @@ -38,6 +39,7 @@ struct mdev_device {
>  	u16 class_id;
>  	union {
>  		const struct vfio_mdev_device_ops *vfio_ops;
> +		const struct virtio_mdev_device_ops *virtio_ops;
>  	};
>  };
>  
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 4625f1a11014..9b69b0bbebfd 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -17,6 +17,7 @@
>  
>  struct mdev_device;
>  struct vfio_mdev_device_ops;
> +struct virtio_mdev_device_ops;
>  
>  /*
>   * Called by the parent device driver to set the device which represents
> @@ -112,6 +113,10 @@ void mdev_set_class(struct mdev_device *mdev, u16 id);
>  void mdev_set_vfio_ops(struct mdev_device *mdev,
>  		       const struct vfio_mdev_device_ops *vfio_ops);
>  const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev);
> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> +			 const struct virtio_mdev_device_ops *virtio_ops);
> +const struct virtio_mdev_device_ops *
> +mdev_get_virtio_ops(struct mdev_device *mdev);
>  
>  extern struct bus_type mdev_bus_type;
>  
> @@ -127,6 +132,7 @@ struct mdev_device *mdev_from_dev(struct device *dev);
>  
>  enum {
>  	MDEV_CLASS_ID_VFIO = 1,
> +	MDEV_CLASS_ID_VIRTIO = 2,
>  	/* New entries must be added here */
>  };
>  
> diff --git a/include/linux/virtio_mdev_ops.h b/include/linux/virtio_mdev_ops.h
> new file mode 100644
> index 000000000000..d417b41f2845
> --- /dev/null
> +++ b/include/linux/virtio_mdev_ops.h
> @@ -0,0 +1,159 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Virtio mediated device driver
> + *
> + * Copyright 2019, Red Hat Corp.
> + *     Author: Jason Wang <jasowang@redhat.com>
> + */
> +#ifndef _LINUX_VIRTIO_MDEV_H
> +#define _LINUX_VIRTIO_MDEV_H
> +
> +#include <linux/interrupt.h>
> +#include <linux/mdev.h>
> +#include <uapi/linux/vhost.h>
> +
> +#define VIRTIO_MDEV_DEVICE_API_STRING		"virtio-mdev"
> +#define VIRTIO_MDEV_F_VERSION_1 0x1
> +
> +struct virtio_mdev_callback {
> +	irqreturn_t (*callback)(void *data);
> +	void *private;
> +};
> +
> +/**
> + * struct vfio_mdev_device_ops - Structure to be registered for each
> + * mdev device to register the device for virtio/vhost drivers.
> + *
> + * The device ops that is supported by VIRTIO_MDEV_F_VERSION_1, the
> + * callbacks are mandatory unless explicity mentioned.

If the version of the callbacks is returned by a callback within the
structure defined by the version... isn't that a bit circular?  This
seems redundant to me versus the class id.  The fact that the parent
driver defines the device as MDEV_CLASS_ID_VIRTIO should tell us this
already.  If it was incremented, we'd need an MDEV_CLASS_ID_VIRTIOv2,
which the virtio-mdev bus driver could add to its id table and handle
differently.

> + *
> + * @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
> + * @get_features:		Set virtio features supported by the driver
       ^ s/g/s/

Thanks,
Alex


> + *				@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_mdev_features:		Get a set of bits that demonstrate
> + *				thecapability of the mdev device. New
> + *				features bits must be added when
> + *				introducing new device ops.
> + *				@mdev: mediated device
> + *				Returns the mdev features (API) support by
> + *				the device.
> + * @get_generation:		Get device config generaton (optionally)
> + *				@mdev: mediated device
> + *				Returns u32: device generation
> + */
> +struct virtio_mdev_device_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);
> +
> +	/* Virtio 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);
> +
> +	/* Mdev device ops */
> +	u64 (*get_mdev_features)(struct mdev_device *mdev);
> +};
> +
> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> +			 const struct virtio_mdev_device_ops *virtio_ops);
> +
> +#endif

Re: [PATCH V5 4/6] mdev: introduce virtio device and its device ops

[Jason Wang]

On 2019/10/24 上午5:57, Alex Williamson wrote:
> On Wed, 23 Oct 2019 21:07:50 +0800
> Jason Wang <jasowang@redhat.com> wrote:
>
>> This patch implements basic support for mdev driver that supports
>> virtio transport for kernel virtio driver.
>>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>   drivers/vfio/mdev/mdev_core.c    |  20 ++++
>>   drivers/vfio/mdev/mdev_private.h |   2 +
>>   include/linux/mdev.h             |   6 ++
>>   include/linux/virtio_mdev_ops.h  | 159 +++++++++++++++++++++++++++++++
>>   4 files changed, 187 insertions(+)
>>   create mode 100644 include/linux/virtio_mdev_ops.h
>>
>> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
>> index 555bd61d8c38..9b00c3513120 100644
>> --- a/drivers/vfio/mdev/mdev_core.c
>> +++ b/drivers/vfio/mdev/mdev_core.c
>> @@ -76,6 +76,26 @@ const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev)
>>   }
>>   EXPORT_SYMBOL(mdev_get_vfio_ops);
>>   
>> +/* Specify the virtio device ops for the mdev device, this
>> + * must be called during create() callback for virtio mdev device.
>> + */
>> +void mdev_set_virtio_ops(struct mdev_device *mdev,
>> +			 const struct virtio_mdev_device_ops *virtio_ops)
>> +{
>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VIRTIO);
>> +	mdev->virtio_ops = virtio_ops;
>> +}
>> +EXPORT_SYMBOL(mdev_set_virtio_ops);
>> +
>> +/* Get the virtio device ops for the mdev device. */
>> +const struct virtio_mdev_device_ops *
>> +mdev_get_virtio_ops(struct mdev_device *mdev)
>> +{
>> +	WARN_ON(mdev->class_id != MDEV_CLASS_ID_VIRTIO);
>> +	return mdev->virtio_ops;
>> +}
>> +EXPORT_SYMBOL(mdev_get_virtio_ops);
>> +
>>   struct device *mdev_dev(struct mdev_device *mdev)
>>   {
>>   	return &mdev->dev;
>> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
>> index 0770410ded2a..7b47890c34e7 100644
>> --- a/drivers/vfio/mdev/mdev_private.h
>> +++ b/drivers/vfio/mdev/mdev_private.h
>> @@ -11,6 +11,7 @@
>>   #define MDEV_PRIVATE_H
>>   
>>   #include <linux/vfio_mdev_ops.h>
>> +#include <linux/virtio_mdev_ops.h>
>>   
>>   int  mdev_bus_register(void);
>>   void mdev_bus_unregister(void);
>> @@ -38,6 +39,7 @@ struct mdev_device {
>>   	u16 class_id;
>>   	union {
>>   		const struct vfio_mdev_device_ops *vfio_ops;
>> +		const struct virtio_mdev_device_ops *virtio_ops;
>>   	};
>>   };
>>   
>> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
>> index 4625f1a11014..9b69b0bbebfd 100644
>> --- a/include/linux/mdev.h
>> +++ b/include/linux/mdev.h
>> @@ -17,6 +17,7 @@
>>   
>>   struct mdev_device;
>>   struct vfio_mdev_device_ops;
>> +struct virtio_mdev_device_ops;
>>   
>>   /*
>>    * Called by the parent device driver to set the device which represents
>> @@ -112,6 +113,10 @@ void mdev_set_class(struct mdev_device *mdev, u16 id);
>>   void mdev_set_vfio_ops(struct mdev_device *mdev,
>>   		       const struct vfio_mdev_device_ops *vfio_ops);
>>   const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev);
>> +void mdev_set_virtio_ops(struct mdev_device *mdev,
>> +			 const struct virtio_mdev_device_ops *virtio_ops);
>> +const struct virtio_mdev_device_ops *
>> +mdev_get_virtio_ops(struct mdev_device *mdev);
>>   
>>   extern struct bus_type mdev_bus_type;
>>   
>> @@ -127,6 +132,7 @@ struct mdev_device *mdev_from_dev(struct device *dev);
>>   
>>   enum {
>>   	MDEV_CLASS_ID_VFIO = 1,
>> +	MDEV_CLASS_ID_VIRTIO = 2,
>>   	/* New entries must be added here */
>>   };
>>   
>> diff --git a/include/linux/virtio_mdev_ops.h b/include/linux/virtio_mdev_ops.h
>> new file mode 100644
>> index 000000000000..d417b41f2845
>> --- /dev/null
>> +++ b/include/linux/virtio_mdev_ops.h
>> @@ -0,0 +1,159 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Virtio mediated device driver
>> + *
>> + * Copyright 2019, Red Hat Corp.
>> + *     Author: Jason Wang <jasowang@redhat.com>
>> + */
>> +#ifndef _LINUX_VIRTIO_MDEV_H
>> +#define _LINUX_VIRTIO_MDEV_H
>> +
>> +#include <linux/interrupt.h>
>> +#include <linux/mdev.h>
>> +#include <uapi/linux/vhost.h>
>> +
>> +#define VIRTIO_MDEV_DEVICE_API_STRING		"virtio-mdev"
>> +#define VIRTIO_MDEV_F_VERSION_1 0x1
>> +
>> +struct virtio_mdev_callback {
>> +	irqreturn_t (*callback)(void *data);
>> +	void *private;
>> +};
>> +
>> +/**
>> + * struct vfio_mdev_device_ops - Structure to be registered for each
>> + * mdev device to register the device for virtio/vhost drivers.
>> + *
>> + * The device ops that is supported by VIRTIO_MDEV_F_VERSION_1, the
>> + * callbacks are mandatory unless explicity mentioned.
> If the version of the callbacks is returned by a callback within the
> structure defined by the version... isn't that a bit circular?  This
> seems redundant to me versus the class id.  The fact that the parent
> driver defines the device as MDEV_CLASS_ID_VIRTIO should tell us this
> already.  If it was incremented, we'd need an MDEV_CLASS_ID_VIRTIOv2,
> which the virtio-mdev bus driver could add to its id table and handle
> differently.


My understanding is versions are only allowed to increase monotonically, 
this seems less flexible than features. E.g we have features A, B, C, 
mdev device can choose to support only a subset. E.g when mdev device 
can support dirty page logging, it can add a new feature bit for driver 
to know that it support new device ops. MDEV_CLASS_ID_VIRTIOv2 may only 
be useful when we will invent a complete new API.


>
>> + *
>> + * @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
>> + * @get_features:		Set virtio features supported by the driver
>         ^ s/g/s/
>
> Thanks,
> Alex


Will fix.

Thanks


>
>> + *				@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_mdev_features:		Get a set of bits that demonstrate
>> + *				thecapability of the mdev device. New
>> + *				features bits must be added when
>> + *				introducing new device ops.
>> + *				@mdev: mediated device
>> + *				Returns the mdev features (API) support by
>> + *				the device.
>> + * @get_generation:		Get device config generaton (optionally)
>> + *				@mdev: mediated device
>> + *				Returns u32: device generation
>> + */
>> +struct virtio_mdev_device_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);
>> +
>> +	/* Virtio 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);
>> +
>> +	/* Mdev device ops */
>> +	u64 (*get_mdev_features)(struct mdev_device *mdev);
>> +};
>> +
>> +void mdev_set_virtio_ops(struct mdev_device *mdev,
>> +			 const struct virtio_mdev_device_ops *virtio_ops);
>> +
>> +#endif

Re: [PATCH V5 4/6] mdev: introduce virtio device and its device ops

[Alex Williamson]

On Thu, 24 Oct 2019 11:51:35 +0800
Jason Wang <jasowang@redhat.com> wrote:

> On 2019/10/24 上午5:57, Alex Williamson wrote:
> > On Wed, 23 Oct 2019 21:07:50 +0800
> > Jason Wang <jasowang@redhat.com> wrote:
> >  
> >> This patch implements basic support for mdev driver that supports
> >> virtio transport for kernel virtio driver.
> >>
> >> Signed-off-by: Jason Wang <jasowang@redhat.com>
> >> ---
> >>   drivers/vfio/mdev/mdev_core.c    |  20 ++++
> >>   drivers/vfio/mdev/mdev_private.h |   2 +
> >>   include/linux/mdev.h             |   6 ++
> >>   include/linux/virtio_mdev_ops.h  | 159 +++++++++++++++++++++++++++++++
> >>   4 files changed, 187 insertions(+)
> >>   create mode 100644 include/linux/virtio_mdev_ops.h
> >>
> >> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> >> index 555bd61d8c38..9b00c3513120 100644
> >> --- a/drivers/vfio/mdev/mdev_core.c
> >> +++ b/drivers/vfio/mdev/mdev_core.c
> >> @@ -76,6 +76,26 @@ const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev)
> >>   }
> >>   EXPORT_SYMBOL(mdev_get_vfio_ops);
> >>   
> >> +/* Specify the virtio device ops for the mdev device, this
> >> + * must be called during create() callback for virtio mdev device.
> >> + */
> >> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> >> +			 const struct virtio_mdev_device_ops *virtio_ops)
> >> +{
> >> +	mdev_set_class(mdev, MDEV_CLASS_ID_VIRTIO);
> >> +	mdev->virtio_ops = virtio_ops;
> >> +}
> >> +EXPORT_SYMBOL(mdev_set_virtio_ops);
> >> +
> >> +/* Get the virtio device ops for the mdev device. */
> >> +const struct virtio_mdev_device_ops *
> >> +mdev_get_virtio_ops(struct mdev_device *mdev)
> >> +{
> >> +	WARN_ON(mdev->class_id != MDEV_CLASS_ID_VIRTIO);
> >> +	return mdev->virtio_ops;
> >> +}
> >> +EXPORT_SYMBOL(mdev_get_virtio_ops);
> >> +
> >>   struct device *mdev_dev(struct mdev_device *mdev)
> >>   {
> >>   	return &mdev->dev;
> >> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
> >> index 0770410ded2a..7b47890c34e7 100644
> >> --- a/drivers/vfio/mdev/mdev_private.h
> >> +++ b/drivers/vfio/mdev/mdev_private.h
> >> @@ -11,6 +11,7 @@
> >>   #define MDEV_PRIVATE_H
> >>   
> >>   #include <linux/vfio_mdev_ops.h>
> >> +#include <linux/virtio_mdev_ops.h>
> >>   
> >>   int  mdev_bus_register(void);
> >>   void mdev_bus_unregister(void);
> >> @@ -38,6 +39,7 @@ struct mdev_device {
> >>   	u16 class_id;
> >>   	union {
> >>   		const struct vfio_mdev_device_ops *vfio_ops;
> >> +		const struct virtio_mdev_device_ops *virtio_ops;
> >>   	};
> >>   };
> >>   
> >> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> >> index 4625f1a11014..9b69b0bbebfd 100644
> >> --- a/include/linux/mdev.h
> >> +++ b/include/linux/mdev.h
> >> @@ -17,6 +17,7 @@
> >>   
> >>   struct mdev_device;
> >>   struct vfio_mdev_device_ops;
> >> +struct virtio_mdev_device_ops;
> >>   
> >>   /*
> >>    * Called by the parent device driver to set the device which represents
> >> @@ -112,6 +113,10 @@ void mdev_set_class(struct mdev_device *mdev, u16 id);
> >>   void mdev_set_vfio_ops(struct mdev_device *mdev,
> >>   		       const struct vfio_mdev_device_ops *vfio_ops);
> >>   const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev);
> >> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> >> +			 const struct virtio_mdev_device_ops *virtio_ops);
> >> +const struct virtio_mdev_device_ops *
> >> +mdev_get_virtio_ops(struct mdev_device *mdev);
> >>   
> >>   extern struct bus_type mdev_bus_type;
> >>   
> >> @@ -127,6 +132,7 @@ struct mdev_device *mdev_from_dev(struct device *dev);
> >>   
> >>   enum {
> >>   	MDEV_CLASS_ID_VFIO = 1,
> >> +	MDEV_CLASS_ID_VIRTIO = 2,
> >>   	/* New entries must be added here */
> >>   };
> >>   
> >> diff --git a/include/linux/virtio_mdev_ops.h b/include/linux/virtio_mdev_ops.h
> >> new file mode 100644
> >> index 000000000000..d417b41f2845
> >> --- /dev/null
> >> +++ b/include/linux/virtio_mdev_ops.h
> >> @@ -0,0 +1,159 @@
> >> +/* SPDX-License-Identifier: GPL-2.0-only */
> >> +/*
> >> + * Virtio mediated device driver
> >> + *
> >> + * Copyright 2019, Red Hat Corp.
> >> + *     Author: Jason Wang <jasowang@redhat.com>
> >> + */
> >> +#ifndef _LINUX_VIRTIO_MDEV_H
> >> +#define _LINUX_VIRTIO_MDEV_H
> >> +
> >> +#include <linux/interrupt.h>
> >> +#include <linux/mdev.h>
> >> +#include <uapi/linux/vhost.h>
> >> +
> >> +#define VIRTIO_MDEV_DEVICE_API_STRING		"virtio-mdev"
> >> +#define VIRTIO_MDEV_F_VERSION_1 0x1
> >> +
> >> +struct virtio_mdev_callback {
> >> +	irqreturn_t (*callback)(void *data);
> >> +	void *private;
> >> +};
> >> +
> >> +/**
> >> + * struct vfio_mdev_device_ops - Structure to be registered for each
> >> + * mdev device to register the device for virtio/vhost drivers.
> >> + *
> >> + * The device ops that is supported by VIRTIO_MDEV_F_VERSION_1, the
> >> + * callbacks are mandatory unless explicity mentioned.  
> > If the version of the callbacks is returned by a callback within the
> > structure defined by the version... isn't that a bit circular?  This
> > seems redundant to me versus the class id.  The fact that the parent
> > driver defines the device as MDEV_CLASS_ID_VIRTIO should tell us this
> > already.  If it was incremented, we'd need an MDEV_CLASS_ID_VIRTIOv2,
> > which the virtio-mdev bus driver could add to its id table and handle
> > differently.  
> 
> 
> My understanding is versions are only allowed to increase monotonically, 
> this seems less flexible than features. E.g we have features A, B, C, 
> mdev device can choose to support only a subset. E.g when mdev device 
> can support dirty page logging, it can add a new feature bit for driver 
> to know that it support new device ops. MDEV_CLASS_ID_VIRTIOv2 may only 
> be useful when we will invent a complete new API.

But this interface rather conflates features and versions by returning
a version as a feature.  If we simply want to say that there are no
additional features, then get_mdev_features() should return an empty
set.  If dirty page logging is a feature, then I'd expect a bit in the
get_mdev_features() return value to identify that feature.

However, I've been under the impression (perhaps wrongly) that the
class-id has a 1:1 correlation to the device-ops exposed to the bus
driver, so if dirty page logging requires extra callbacks, that would
imply a new device-ops, which requires a new class-id.  In that case
virtio-mdev would claim both class-ids and would need some way to
differentiate them.  But I also see that such a solution can become
unmanageable as the set of class-ids would need to encompass every
combination of features.

So I think what's suggested by this is that the initial struct
virtio_mdev_device_ops is a base set of callbacks which would be
extended via features?  But then why does get_generation() not make use
of this?  And if we can define get_generation() as optional and simply
test if it's implemented, then it seems we don't need any feature bits
to extend the structure (unless we're looking at binary compatibility).
So maybe get_mdev_features() is meant to expose underlying features
unrelated to the callbacks?  Which is not in line with the description?
Hopefully you can see my confusion in what we're trying to do here.
Thanks,

Alex

> >> + *
> >> + * @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
> >> + * @get_features:		Set virtio features supported by the driver  
> >         ^ s/g/s/
> >
> > Thanks,
> > Alex  
> 
> 
> Will fix.
> 
> Thanks
> 
> 
> >  
> >> + *				@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_mdev_features:		Get a set of bits that demonstrate
> >> + *				thecapability of the mdev device. New
> >> + *				features bits must be added when
> >> + *				introducing new device ops.
> >> + *				@mdev: mediated device
> >> + *				Returns the mdev features (API) support by
> >> + *				the device.
> >> + * @get_generation:		Get device config generaton (optionally)
> >> + *				@mdev: mediated device
> >> + *				Returns u32: device generation
> >> + */
> >> +struct virtio_mdev_device_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);
> >> +
> >> +	/* Virtio 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);
> >> +
> >> +	/* Mdev device ops */
> >> +	u64 (*get_mdev_features)(struct mdev_device *mdev);
> >> +};
> >> +
> >> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> >> +			 const struct virtio_mdev_device_ops *virtio_ops);
> >> +
> >> +#endif  

Re: [PATCH V5 4/6] mdev: introduce virtio device and its device ops

[Jason Wang]

On 2019/10/25 上午4:44, Alex Williamson wrote:
> On Thu, 24 Oct 2019 11:51:35 +0800
> Jason Wang<jasowang@redhat.com>  wrote:
>
>> On 2019/10/24 上午5:57, Alex Williamson wrote:
>>> On Wed, 23 Oct 2019 21:07:50 +0800
>>> Jason Wang<jasowang@redhat.com>  wrote:
>>>   
>>>> This patch implements basic support for mdev driver that supports
>>>> virtio transport for kernel virtio driver.
>>>>
>>>> Signed-off-by: Jason Wang<jasowang@redhat.com>
>>>> ---
>>>>    drivers/vfio/mdev/mdev_core.c    |  20 ++++
>>>>    drivers/vfio/mdev/mdev_private.h |   2 +
>>>>    include/linux/mdev.h             |   6 ++
>>>>    include/linux/virtio_mdev_ops.h  | 159 +++++++++++++++++++++++++++++++
>>>>    4 files changed, 187 insertions(+)
>>>>    create mode 100644 include/linux/virtio_mdev_ops.h
>>>>
>>>> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
>>>> index 555bd61d8c38..9b00c3513120 100644
>>>> --- a/drivers/vfio/mdev/mdev_core.c
>>>> +++ b/drivers/vfio/mdev/mdev_core.c
>>>> @@ -76,6 +76,26 @@ const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev)
>>>>    }
>>>>    EXPORT_SYMBOL(mdev_get_vfio_ops);
>>>>    
>>>> +/* Specify the virtio device ops for the mdev device, this
>>>> + * must be called during create() callback for virtio mdev device.
>>>> + */
>>>> +void mdev_set_virtio_ops(struct mdev_device *mdev,
>>>> +			 const struct virtio_mdev_device_ops *virtio_ops)
>>>> +{
>>>> +	mdev_set_class(mdev, MDEV_CLASS_ID_VIRTIO);
>>>> +	mdev->virtio_ops = virtio_ops;
>>>> +}
>>>> +EXPORT_SYMBOL(mdev_set_virtio_ops);
>>>> +
>>>> +/* Get the virtio device ops for the mdev device. */
>>>> +const struct virtio_mdev_device_ops *
>>>> +mdev_get_virtio_ops(struct mdev_device *mdev)
>>>> +{
>>>> +	WARN_ON(mdev->class_id != MDEV_CLASS_ID_VIRTIO);
>>>> +	return mdev->virtio_ops;
>>>> +}
>>>> +EXPORT_SYMBOL(mdev_get_virtio_ops);
>>>> +
>>>>    struct device *mdev_dev(struct mdev_device *mdev)
>>>>    {
>>>>    	return &mdev->dev;
>>>> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
>>>> index 0770410ded2a..7b47890c34e7 100644
>>>> --- a/drivers/vfio/mdev/mdev_private.h
>>>> +++ b/drivers/vfio/mdev/mdev_private.h
>>>> @@ -11,6 +11,7 @@
>>>>    #define MDEV_PRIVATE_H
>>>>    
>>>>    #include <linux/vfio_mdev_ops.h>
>>>> +#include <linux/virtio_mdev_ops.h>
>>>>    
>>>>    int  mdev_bus_register(void);
>>>>    void mdev_bus_unregister(void);
>>>> @@ -38,6 +39,7 @@ struct mdev_device {
>>>>    	u16 class_id;
>>>>    	union {
>>>>    		const struct vfio_mdev_device_ops *vfio_ops;
>>>> +		const struct virtio_mdev_device_ops *virtio_ops;
>>>>    	};
>>>>    };
>>>>    
>>>> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
>>>> index 4625f1a11014..9b69b0bbebfd 100644
>>>> --- a/include/linux/mdev.h
>>>> +++ b/include/linux/mdev.h
>>>> @@ -17,6 +17,7 @@
>>>>    
>>>>    struct mdev_device;
>>>>    struct vfio_mdev_device_ops;
>>>> +struct virtio_mdev_device_ops;
>>>>    
>>>>    /*
>>>>     * Called by the parent device driver to set the device which represents
>>>> @@ -112,6 +113,10 @@ void mdev_set_class(struct mdev_device *mdev, u16 id);
>>>>    void mdev_set_vfio_ops(struct mdev_device *mdev,
>>>>    		       const struct vfio_mdev_device_ops *vfio_ops);
>>>>    const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev);
>>>> +void mdev_set_virtio_ops(struct mdev_device *mdev,
>>>> +			 const struct virtio_mdev_device_ops *virtio_ops);
>>>> +const struct virtio_mdev_device_ops *
>>>> +mdev_get_virtio_ops(struct mdev_device *mdev);
>>>>    
>>>>    extern struct bus_type mdev_bus_type;
>>>>    
>>>> @@ -127,6 +132,7 @@ struct mdev_device *mdev_from_dev(struct device *dev);
>>>>    
>>>>    enum {
>>>>    	MDEV_CLASS_ID_VFIO = 1,
>>>> +	MDEV_CLASS_ID_VIRTIO = 2,
>>>>    	/* New entries must be added here */
>>>>    };
>>>>    
>>>> diff --git a/include/linux/virtio_mdev_ops.h b/include/linux/virtio_mdev_ops.h
>>>> new file mode 100644
>>>> index 000000000000..d417b41f2845
>>>> --- /dev/null
>>>> +++ b/include/linux/virtio_mdev_ops.h
>>>> @@ -0,0 +1,159 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0-only */
>>>> +/*
>>>> + * Virtio mediated device driver
>>>> + *
>>>> + * Copyright 2019, Red Hat Corp.
>>>> + *     Author: Jason Wang<jasowang@redhat.com>
>>>> + */
>>>> +#ifndef _LINUX_VIRTIO_MDEV_H
>>>> +#define _LINUX_VIRTIO_MDEV_H
>>>> +
>>>> +#include <linux/interrupt.h>
>>>> +#include <linux/mdev.h>
>>>> +#include <uapi/linux/vhost.h>
>>>> +
>>>> +#define VIRTIO_MDEV_DEVICE_API_STRING		"virtio-mdev"
>>>> +#define VIRTIO_MDEV_F_VERSION_1 0x1
>>>> +
>>>> +struct virtio_mdev_callback {
>>>> +	irqreturn_t (*callback)(void *data);
>>>> +	void *private;
>>>> +};
>>>> +
>>>> +/**
>>>> + * struct vfio_mdev_device_ops - Structure to be registered for each
>>>> + * mdev device to register the device for virtio/vhost drivers.
>>>> + *
>>>> + * The device ops that is supported by VIRTIO_MDEV_F_VERSION_1, the
>>>> + * callbacks are mandatory unless explicity mentioned.
>>> If the version of the callbacks is returned by a callback within the
>>> structure defined by the version... isn't that a bit circular?  This
>>> seems redundant to me versus the class id.  The fact that the parent
>>> driver defines the device as MDEV_CLASS_ID_VIRTIO should tell us this
>>> already.  If it was incremented, we'd need an MDEV_CLASS_ID_VIRTIOv2,
>>> which the virtio-mdev bus driver could add to its id table and handle
>>> differently.
>> My understanding is versions are only allowed to increase monotonically,
>> this seems less flexible than features. E.g we have features A, B, C,
>> mdev device can choose to support only a subset. E.g when mdev device
>> can support dirty page logging, it can add a new feature bit for driver
>> to know that it support new device ops. MDEV_CLASS_ID_VIRTIOv2 may only
>> be useful when we will invent a complete new API.
> But this interface rather conflates features and versions by returning
> a version as a feature.  If we simply want to say that there are no
> additional features, then get_mdev_features() should return an empty
> set.  If dirty page logging is a feature, then I'd expect a bit in the
> get_mdev_features() return value to identify that feature.
>
> However, I've been under the impression (perhaps wrongly) that the
> class-id has a 1:1 correlation to the device-ops exposed to the bus
> driver, so if dirty page logging requires extra callbacks, that would
> imply a new device-ops, which requires a new class-id.  In that case
> virtio-mdev would claim both class-ids and would need some way to
> differentiate them.  But I also see that such a solution can become
> unmanageable as the set of class-ids would need to encompass every
> combination of features.
>
> So I think what's suggested by this is that the initial struct
> virtio_mdev_device_ops is a base set of callbacks which would be
> extended via features?


Yes.


> But then why does get_generation() not make use
> of this?  And if we can define get_generation() as optional and simply
> test if it's implemented, then it seems we don't need any feature bits
> to extend the structure (unless we're looking at binary compatibility).


I think the mapping between ops and features is N:1. We start with a 
base feature like VIRTIO_MDEV_VERSION_1, this allows us to do simply 
checking during probe without the need to checking the existence of each 
op. Testing the existence of a specific op should work but less 
convenient when a feature requires several new ops. For the case of 
get_generation(), it works because the bus driver have workaround when 
parent doesn't provide that. This may not work for a real feature.


> So maybe get_mdev_features() is meant to expose underlying features
> unrelated to the callbacks?  Which is not in line with the description?


At least not for current virtio-mdev/vhost-mdev. Virtio specific 
features should be done via get_features().


> Hopefully you can see my confusion in what we're trying to do here.


I think I get you and hope my answer make sense. Suggestions are welcomed.

Thanks


> Thanks,
>
> Alex
>

Re: [PATCH V5 4/6] mdev: introduce virtio device and its device ops

[Zhu Lingshan]

On 10/23/2019 9:07 PM, Jason Wang wrote:
> This patch implements basic support for mdev driver that supports
> virtio transport for kernel virtio driver.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>   drivers/vfio/mdev/mdev_core.c    |  20 ++++
>   drivers/vfio/mdev/mdev_private.h |   2 +
>   include/linux/mdev.h             |   6 ++
>   include/linux/virtio_mdev_ops.h  | 159 +++++++++++++++++++++++++++++++
>   4 files changed, 187 insertions(+)
>   create mode 100644 include/linux/virtio_mdev_ops.h
>
> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
> index 555bd61d8c38..9b00c3513120 100644
> --- a/drivers/vfio/mdev/mdev_core.c
> +++ b/drivers/vfio/mdev/mdev_core.c
> @@ -76,6 +76,26 @@ const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev)
>   }
>   EXPORT_SYMBOL(mdev_get_vfio_ops);
>   
> +/* Specify the virtio device ops for the mdev device, this
> + * must be called during create() callback for virtio mdev device.
> + */
> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> +			 const struct virtio_mdev_device_ops *virtio_ops)
> +{
> +	mdev_set_class(mdev, MDEV_CLASS_ID_VIRTIO);
> +	mdev->virtio_ops = virtio_ops;
> +}
> +EXPORT_SYMBOL(mdev_set_virtio_ops);
> +
> +/* Get the virtio device ops for the mdev device. */
> +const struct virtio_mdev_device_ops *
> +mdev_get_virtio_ops(struct mdev_device *mdev)
> +{
> +	WARN_ON(mdev->class_id != MDEV_CLASS_ID_VIRTIO);
> +	return mdev->virtio_ops;
> +}
> +EXPORT_SYMBOL(mdev_get_virtio_ops);
> +
>   struct device *mdev_dev(struct mdev_device *mdev)
>   {
>   	return &mdev->dev;
> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
> index 0770410ded2a..7b47890c34e7 100644
> --- a/drivers/vfio/mdev/mdev_private.h
> +++ b/drivers/vfio/mdev/mdev_private.h
> @@ -11,6 +11,7 @@
>   #define MDEV_PRIVATE_H
>   
>   #include <linux/vfio_mdev_ops.h>
> +#include <linux/virtio_mdev_ops.h>
>   
>   int  mdev_bus_register(void);
>   void mdev_bus_unregister(void);
> @@ -38,6 +39,7 @@ struct mdev_device {
>   	u16 class_id;
>   	union {
>   		const struct vfio_mdev_device_ops *vfio_ops;
> +		const struct virtio_mdev_device_ops *virtio_ops;
>   	};
>   };
>   
> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
> index 4625f1a11014..9b69b0bbebfd 100644
> --- a/include/linux/mdev.h
> +++ b/include/linux/mdev.h
> @@ -17,6 +17,7 @@
>   
>   struct mdev_device;
>   struct vfio_mdev_device_ops;
> +struct virtio_mdev_device_ops;
>   
>   /*
>    * Called by the parent device driver to set the device which represents
> @@ -112,6 +113,10 @@ void mdev_set_class(struct mdev_device *mdev, u16 id);
>   void mdev_set_vfio_ops(struct mdev_device *mdev,
>   		       const struct vfio_mdev_device_ops *vfio_ops);
>   const struct vfio_mdev_device_ops *mdev_get_vfio_ops(struct mdev_device *mdev);
> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> +			 const struct virtio_mdev_device_ops *virtio_ops);
> +const struct virtio_mdev_device_ops *
> +mdev_get_virtio_ops(struct mdev_device *mdev);
>   
>   extern struct bus_type mdev_bus_type;
>   
> @@ -127,6 +132,7 @@ struct mdev_device *mdev_from_dev(struct device *dev);
>   
>   enum {
>   	MDEV_CLASS_ID_VFIO = 1,
> +	MDEV_CLASS_ID_VIRTIO = 2,
>   	/* New entries must be added here */
>   };
>   
> diff --git a/include/linux/virtio_mdev_ops.h b/include/linux/virtio_mdev_ops.h
> new file mode 100644
> index 000000000000..d417b41f2845
> --- /dev/null
> +++ b/include/linux/virtio_mdev_ops.h
> @@ -0,0 +1,159 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Virtio mediated device driver
> + *
> + * Copyright 2019, Red Hat Corp.
> + *     Author: Jason Wang <jasowang@redhat.com>
> + */
> +#ifndef _LINUX_VIRTIO_MDEV_H
> +#define _LINUX_VIRTIO_MDEV_H
> +
> +#include <linux/interrupt.h>
> +#include <linux/mdev.h>
> +#include <uapi/linux/vhost.h>
> +
> +#define VIRTIO_MDEV_DEVICE_API_STRING		"virtio-mdev"
> +#define VIRTIO_MDEV_F_VERSION_1 0x1
> +
> +struct virtio_mdev_callback {
> +	irqreturn_t (*callback)(void *data);
> +	void *private;
> +};
> +
> +/**
> + * struct vfio_mdev_device_ops - Structure to be registered for each
> + * mdev device to register the device for virtio/vhost drivers.
> + *
> + * The device ops that is supported by VIRTIO_MDEV_F_VERSION_1, the
> + * callbacks are mandatory unless explicity 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
> + * @get_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_mdev_features:		Get a set of bits that demonstrate
> + *				thecapability of the mdev device. New
> + *				features bits must be added when
> + *				introducing new device ops.
> + *				@mdev: mediated device
> + *				Returns the mdev features (API) support by
> + *				the device.
> + * @get_generation:		Get device config generaton (optionally)
> + *				@mdev: mediated device
> + *				Returns u32: device generation
> + */
> +struct virtio_mdev_device_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);
> +
> +	/* Virtio 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);

Hi Jason

Is it possible to make set_status() return an u8 or bool, because this 
may fail in real hardware. Without a returned code, I am not sure  
whether it is a good idea to set the status | NEED_RESET when fail.

Thanks,
BR
Zhu Lingshan
> +	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);
> +
> +	/* Mdev device ops */
> +	u64 (*get_mdev_features)(struct mdev_device *mdev);
> +};
> +
> +void mdev_set_virtio_ops(struct mdev_device *mdev,
> +			 const struct virtio_mdev_device_ops *virtio_ops);
> +
> +#endif

Re: [PATCH V5 4/6] mdev: introduce virtio device and its device ops

[Jason Wang]

On 2019/10/29 下午3:42, Zhu Lingshan wrote:
>>
>> +    void (*set_status)(struct mdev_device *mdev, u8 status);
>
> Hi Jason
>
> Is it possible to make set_status() return an u8 or bool, because this
> may fail in real hardware. Without a returned code, I am not sure 
> whether it is a good idea to set the status | NEED_RESET when fail.
>
> Thanks,
> BR
> Zhu Lingshan 


Hi:


It's possible but I'm not sure whether any user will care about it. E.g
see virtio_add_status():

void virtio_add_status(struct virtio_device *dev, unsigned int status)
{
    might_sleep();
    dev->config->set_status(dev, dev->config->get_status(dev) | status);
}
EXPORT_SYMBOL_GPL(virtio_add_status);

And I believe how it work should be:

virtio_add_status(xyz);

status = virtio_get_status();

if (!(status & xyz))

    error;

Thanks

Re: [PATCH V5 4/6] mdev: introduce virtio device and its device ops

[Zhu Lingshan]

On 10/29/2019 6:42 PM, Jason Wang wrote:
> On 2019/10/29 下午3:42, Zhu Lingshan wrote:
>>> +    void (*set_status)(struct mdev_device *mdev, u8 status);
>> Hi Jason
>>
>> Is it possible to make set_status() return an u8 or bool, because this
>> may fail in real hardware. Without a returned code, I am not sure
>> whether it is a good idea to set the status | NEED_RESET when fail.
>>
>> Thanks,
>> BR
>> Zhu Lingshan
>
> Hi:
>
>
> It's possible but I'm not sure whether any user will care about it. E.g
> see virtio_add_status():
>
> void virtio_add_status(struct virtio_device *dev, unsigned int status)
> {
>      might_sleep();
>      dev->config->set_status(dev, dev->config->get_status(dev) | status);
> }
> EXPORT_SYMBOL_GPL(virtio_add_status);
>
> And I believe how it work should be:
>
> virtio_add_status(xyz);
>
> status = virtio_get_status();
>
> if (!(status & xyz))
>
>      error;
>
> Thanks
>
Thanks Jason, then I believe upper layer can handle this well.
>

[PATCH V5 5/6] virtio: introduce a mdev based transport

[Jason Wang]

This patch introduces a new mdev transport for virtio. This is used to
use kernel virtio driver to drive the mediated device that is capable
of populating virtqueue directly.

A new virtio-mdev driver will be registered to the mdev bus, when a
new virtio-mdev device is probed, it will register the device with
mdev based config ops. This means it is a software transport between
mdev driver and mdev device. The transport was implemented through
device specific ops which is a part of mdev_parent_ops now.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/virtio/Kconfig       |   7 +
 drivers/virtio/Makefile      |   1 +
 drivers/virtio/virtio_mdev.c | 413 +++++++++++++++++++++++++++++++++++
 3 files changed, 421 insertions(+)
 create mode 100644 drivers/virtio/virtio_mdev.c

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 078615cf2afc..8d18722ab572 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -43,6 +43,13 @@ config VIRTIO_PCI_LEGACY
 
 	  If unsure, say Y.
 
+config VIRTIO_MDEV_DEVICE
+	tristate "VIRTIO driver for Mediated devices"
+	depends on VFIO_MDEV && VIRTIO
+	default n
+	help
+	  VIRTIO based driver for Mediated devices.
+
 config VIRTIO_PMEM
 	tristate "Support for virtio pmem driver"
 	depends on VIRTIO
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index 3a2b5c5dcf46..ebc7fa15ae82 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -6,3 +6,4 @@ virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o
 virtio_pci-$(CONFIG_VIRTIO_PCI_LEGACY) += virtio_pci_legacy.o
 obj-$(CONFIG_VIRTIO_BALLOON) += virtio_balloon.o
 obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o
+obj-$(CONFIG_VIRTIO_MDEV_DEVICE) += virtio_mdev.o
diff --git a/drivers/virtio/virtio_mdev.c b/drivers/virtio/virtio_mdev.c
new file mode 100644
index 000000000000..eb2621f9182c
--- /dev/null
+++ b/drivers/virtio/virtio_mdev.c
@@ -0,0 +1,413 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VIRTIO based driver for Mediated device
+ *
+ * Copyright (c) 2019, Red Hat. All rights reserved.
+ *     Author: Jason Wang <jasowang@redhat.com>
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/uuid.h>
+#include <linux/mdev.h>
+#include <linux/virtio_mdev_ops.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_ring.h>
+
+#define DRIVER_VERSION  "0.1"
+#define DRIVER_AUTHOR   "Red Hat Corporation"
+#define DRIVER_DESC     "VIRTIO based driver for Mediated device"
+
+#define to_virtio_mdev_device(dev) \
+	container_of(dev, struct virtio_mdev_device, vdev)
+
+struct virtio_mdev_device {
+	struct virtio_device vdev;
+	struct mdev_device *mdev;
+	u64 features;
+
+	/* The lock to protect virtqueue list */
+	spinlock_t lock;
+	/* List of virtio_mdev_vq_info */
+	struct list_head virtqueues;
+};
+
+struct virtio_mdev_vq_info {
+	/* the actual virtqueue */
+	struct virtqueue *vq;
+
+	/* the list node for the virtqueues list */
+	struct list_head node;
+};
+
+static struct mdev_device *vm_get_mdev(struct virtio_device *vdev)
+{
+	struct virtio_mdev_device *vm_dev = to_virtio_mdev_device(vdev);
+	struct mdev_device *mdev = vm_dev->mdev;
+
+	return mdev;
+}
+
+static void virtio_mdev_get(struct virtio_device *vdev, unsigned offset,
+			    void *buf, unsigned len)
+{
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+	ops->get_config(mdev, offset, buf, len);
+}
+
+static void virtio_mdev_set(struct virtio_device *vdev, unsigned offset,
+			    const void *buf, unsigned len)
+{
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+	ops->set_config(mdev, offset, buf, len);
+}
+
+static u32 virtio_mdev_generation(struct virtio_device *vdev)
+{
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+	if (ops->get_generation)
+		return ops->get_generation(mdev);
+
+	return 0;
+}
+
+static u8 virtio_mdev_get_status(struct virtio_device *vdev)
+{
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+	return ops->get_status(mdev);
+}
+
+static void virtio_mdev_set_status(struct virtio_device *vdev, u8 status)
+{
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+	return ops->set_status(mdev, status);
+}
+
+static void virtio_mdev_reset(struct virtio_device *vdev)
+{
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+	return ops->set_status(mdev, 0);
+}
+
+static bool virtio_mdev_notify(struct virtqueue *vq)
+{
+	struct mdev_device *mdev = vm_get_mdev(vq->vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+	ops->kick_vq(mdev, vq->index);
+
+	return true;
+}
+
+static irqreturn_t virtio_mdev_config_cb(void *private)
+{
+	struct virtio_mdev_device *vm_dev = private;
+
+	virtio_config_changed(&vm_dev->vdev);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t virtio_mdev_virtqueue_cb(void *private)
+{
+	struct virtio_mdev_vq_info *info = private;
+
+	return vring_interrupt(0, info->vq);
+}
+
+static struct virtqueue *
+virtio_mdev_setup_vq(struct virtio_device *vdev, unsigned index,
+		     void (*callback)(struct virtqueue *vq),
+		     const char *name, bool ctx)
+{
+	struct virtio_mdev_device *vm_dev = to_virtio_mdev_device(vdev);
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+	struct virtio_mdev_vq_info *info;
+	struct virtio_mdev_callback cb;
+	struct virtqueue *vq;
+	u64 desc_addr, driver_addr, device_addr;
+	unsigned long flags;
+	u32 align, num;
+	int err;
+
+	if (!name)
+		return NULL;
+
+	/* Queue shouldn't already be set up. */
+	if (ops->get_vq_ready(mdev, index))
+		return ERR_PTR(-ENOENT);
+
+	/* Allocate and fill out our active queue description */
+	info = kmalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	num = ops->get_vq_num_max(mdev);
+	if (num == 0) {
+		err = -ENOENT;
+		goto error_new_virtqueue;
+	}
+
+	/* Create the vring */
+	align = ops->get_vq_align(mdev);
+	vq = vring_create_virtqueue(index, num, align, vdev,
+				    true, true, ctx,
+				    virtio_mdev_notify, callback, name);
+	if (!vq) {
+		err = -ENOMEM;
+		goto error_new_virtqueue;
+	}
+
+	/* Setup virtqueue callback */
+	cb.callback = virtio_mdev_virtqueue_cb;
+	cb.private = info;
+	ops->set_vq_cb(mdev, index, &cb);
+	ops->set_vq_num(mdev, index, virtqueue_get_vring_size(vq));
+
+	desc_addr = virtqueue_get_desc_addr(vq);
+	driver_addr = virtqueue_get_avail_addr(vq);
+	device_addr = virtqueue_get_used_addr(vq);
+
+	if (ops->set_vq_address(mdev, index,
+				desc_addr, driver_addr,
+				device_addr)) {
+		err = -EINVAL;
+		goto err_vq;
+	}
+
+	ops->set_vq_ready(mdev, index, 1);
+
+	vq->priv = info;
+	info->vq = vq;
+
+	spin_lock_irqsave(&vm_dev->lock, flags);
+	list_add(&info->node, &vm_dev->virtqueues);
+	spin_unlock_irqrestore(&vm_dev->lock, flags);
+
+	return vq;
+
+err_vq:
+	vring_del_virtqueue(vq);
+error_new_virtqueue:
+	ops->set_vq_ready(mdev, index, 0);
+	WARN_ON(ops->get_vq_ready(mdev, index));
+	kfree(info);
+	return ERR_PTR(err);
+
+}
+
+static void virtio_mdev_del_vq(struct virtqueue *vq)
+{
+	struct virtio_mdev_device *vm_dev = to_virtio_mdev_device(vq->vdev);
+	struct mdev_device *mdev = vm_dev->mdev;
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+	struct virtio_mdev_vq_info *info = vq->priv;
+	unsigned int index = vq->index;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vm_dev->lock, flags);
+	list_del(&info->node);
+	spin_unlock_irqrestore(&vm_dev->lock, flags);
+
+	/* Select and deactivate the queue */
+	ops->set_vq_ready(mdev, index, 0);
+	WARN_ON(ops->get_vq_ready(mdev, index));
+
+	vring_del_virtqueue(vq);
+
+	kfree(info);
+}
+
+static void virtio_mdev_del_vqs(struct virtio_device *vdev)
+{
+	struct virtqueue *vq, *n;
+
+	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+		virtio_mdev_del_vq(vq);
+}
+
+static int virtio_mdev_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+				struct virtqueue *vqs[],
+				vq_callback_t *callbacks[],
+				const char * const names[],
+				const bool *ctx,
+				struct irq_affinity *desc)
+{
+	struct virtio_mdev_device *vm_dev = to_virtio_mdev_device(vdev);
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+	struct virtio_mdev_callback cb;
+	int i, err, queue_idx = 0;
+
+	for (i = 0; i < nvqs; ++i) {
+		if (!names[i]) {
+			vqs[i] = NULL;
+			continue;
+		}
+
+		vqs[i] = virtio_mdev_setup_vq(vdev, queue_idx++,
+					      callbacks[i], names[i], ctx ?
+					      ctx[i] : false);
+		if (IS_ERR(vqs[i])) {
+			err = PTR_ERR(vqs[i]);
+			goto err_setup_vq;
+		}
+	}
+
+	cb.callback = virtio_mdev_config_cb;
+	cb.private = vm_dev;
+	ops->set_config_cb(mdev, &cb);
+
+	return 0;
+
+err_setup_vq:
+	virtio_mdev_del_vqs(vdev);
+	return err;
+}
+
+static u64 virtio_mdev_get_features(struct virtio_device *vdev)
+{
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+	return ops->get_features(mdev);
+}
+
+static int virtio_mdev_finalize_features(struct virtio_device *vdev)
+{
+	struct mdev_device *mdev = vm_get_mdev(vdev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+
+	/* Give virtio_ring a chance to accept features. */
+	vring_transport_features(vdev);
+
+	return ops->set_features(mdev, vdev->features);
+}
+
+static const char *virtio_mdev_bus_name(struct virtio_device *vdev)
+{
+	struct virtio_mdev_device *vm_dev = to_virtio_mdev_device(vdev);
+	struct mdev_device *mdev = vm_dev->mdev;
+
+	return dev_name(mdev_dev(mdev));
+}
+
+static const struct virtio_config_ops virtio_mdev_config_ops = {
+	.get		= virtio_mdev_get,
+	.set		= virtio_mdev_set,
+	.generation	= virtio_mdev_generation,
+	.get_status	= virtio_mdev_get_status,
+	.set_status	= virtio_mdev_set_status,
+	.reset		= virtio_mdev_reset,
+	.find_vqs	= virtio_mdev_find_vqs,
+	.del_vqs	= virtio_mdev_del_vqs,
+	.get_features	= virtio_mdev_get_features,
+	.finalize_features = virtio_mdev_finalize_features,
+	.bus_name	= virtio_mdev_bus_name,
+};
+
+static void virtio_mdev_release_dev(struct device *_d)
+{
+	struct virtio_device *vdev =
+	       container_of(_d, struct virtio_device, dev);
+	struct virtio_mdev_device *vm_dev =
+	       container_of(vdev, struct virtio_mdev_device, vdev);
+	struct mdev_device *mdev = vm_dev->mdev;
+
+	devm_kfree(mdev_dev(mdev), vm_dev);
+}
+
+static int virtio_mdev_probe(struct device *dev)
+{
+	struct mdev_device *mdev = mdev_from_dev(dev);
+	const struct virtio_mdev_device_ops *ops = mdev_get_virtio_ops(mdev);
+	struct virtio_mdev_device *vm_dev;
+	int rc;
+
+	vm_dev = devm_kzalloc(dev, sizeof(*vm_dev), GFP_KERNEL);
+	if (!vm_dev)
+		return -ENOMEM;
+
+	vm_dev->vdev.dev.parent = dev;
+	vm_dev->vdev.dev.release = virtio_mdev_release_dev;
+	vm_dev->vdev.config = &virtio_mdev_config_ops;
+	vm_dev->mdev = mdev;
+	INIT_LIST_HEAD(&vm_dev->virtqueues);
+	spin_lock_init(&vm_dev->lock);
+
+	vm_dev->features = ops->get_mdev_features(mdev);
+	if (vm_dev->features != VIRTIO_MDEV_F_VERSION_1) {
+		dev_err(dev, "VIRTIO_MDEV_F_VERSION_1 is mandatory\n");
+		return -ENXIO;
+	}
+
+	vm_dev->vdev.id.device = ops->get_device_id(mdev);
+	if (vm_dev->vdev.id.device == 0)
+		return -ENODEV;
+
+	vm_dev->vdev.id.vendor = ops->get_vendor_id(mdev);
+	rc = register_virtio_device(&vm_dev->vdev);
+	if (rc)
+		put_device(dev);
+	else
+		dev_set_drvdata(dev, vm_dev);
+
+	return rc;
+}
+
+static void virtio_mdev_remove(struct device *dev)
+{
+	struct virtio_mdev_device *vm_dev = dev_get_drvdata(dev);
+
+	unregister_virtio_device(&vm_dev->vdev);
+}
+
+static const struct mdev_class_id id_table[] = {
+	{ MDEV_CLASS_ID_VIRTIO },
+	{ 0 },
+};
+
+MODULE_DEVICE_TABLE(mdev, id_table);
+
+static struct mdev_driver virtio_mdev_driver = {
+	.name	= "virtio_mdev",
+	.probe	= virtio_mdev_probe,
+	.remove = virtio_mdev_remove,
+	.id_table = id_table,
+};
+
+static int __init virtio_mdev_init(void)
+{
+	return mdev_register_driver(&virtio_mdev_driver, THIS_MODULE);
+}
+
+static void __exit virtio_mdev_exit(void)
+{
+	mdev_unregister_driver(&virtio_mdev_driver);
+}
+
+module_init(virtio_mdev_init)
+module_exit(virtio_mdev_exit)
+
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
-- 
2.19.1

[PATCH V5 6/6] docs: sample driver to demonstrate how to implement virtio-mdev framework

[Jason Wang]

This sample driver creates mdev device that simulate virtio net device
over virtio mdev transport. The device is implemented through vringh
and workqueue. A device specific dma ops is to make sure HVA is used
directly as the IOVA. This should be sufficient for kernel virtio
driver to work.

Only 'virtio' type is supported right now. I plan to add 'vhost' type
on top which requires some virtual IOMMU implemented in this sample
driver.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 MAINTAINERS                |   1 +
 samples/Kconfig            |   7 +
 samples/vfio-mdev/Makefile |   1 +
 samples/vfio-mdev/mvnet.c  | 691 +++++++++++++++++++++++++++++++++++++
 4 files changed, 700 insertions(+)
 create mode 100644 samples/vfio-mdev/mvnet.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 9e10ae9c2b4d..8b17927a81fd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17248,6 +17248,7 @@ F:	include/linux/virtio*.h
 F:	include/uapi/linux/virtio_*.h
 F:	drivers/crypto/virtio/
 F:	mm/balloon_compaction.c
+F:	samples/vfio-mdev/mvnet.c
 
 VIRTIO BLOCK AND SCSI DRIVERS
 M:	"Michael S. Tsirkin" <mst@redhat.com>
diff --git a/samples/Kconfig b/samples/Kconfig
index c8dacb4dda80..a1a1ca2c00b7 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -131,6 +131,13 @@ config SAMPLE_VFIO_MDEV_MDPY
 	  mediated device.  It is a simple framebuffer and supports
 	  the region display interface (VFIO_GFX_PLANE_TYPE_REGION).
 
+config SAMPLE_VIRTIO_MDEV_NET
+        tristate "Build virtio mdev net example mediated device sample code -- loadable modules only"
+	depends on VIRTIO_MDEV_DEVICE && VHOST_RING && m
+	help
+	  Build a networking sample device for use as a virtio
+	  mediated device.
+
 config SAMPLE_VFIO_MDEV_MDPY_FB
 	tristate "Build VFIO mdpy example guest fbdev driver -- loadable module only"
 	depends on FB && m
diff --git a/samples/vfio-mdev/Makefile b/samples/vfio-mdev/Makefile
index 10d179c4fdeb..f34af90ed0a0 100644
--- a/samples/vfio-mdev/Makefile
+++ b/samples/vfio-mdev/Makefile
@@ -3,3 +3,4 @@ obj-$(CONFIG_SAMPLE_VFIO_MDEV_MTTY) += mtty.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY) += mdpy.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY_FB) += mdpy-fb.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MBOCHS) += mbochs.o
+obj-$(CONFIG_SAMPLE_VIRTIO_MDEV_NET) += mvnet.o
diff --git a/samples/vfio-mdev/mvnet.c b/samples/vfio-mdev/mvnet.c
new file mode 100644
index 000000000000..a2a902d59fb7
--- /dev/null
+++ b/samples/vfio-mdev/mvnet.c
@@ -0,0 +1,691 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Mediated virtual virtio-net device driver.
+ *
+ * Copyright (c) 2019, Red Hat Inc. All rights reserved.
+ *     Author: Jason Wang <jasowang@redhat.com>
+ *
+ * Sample driver that creates mdev device that simulates ethernet loopback
+ * device.
+ *
+ * Usage:
+ *
+ * # modprobe virtio_mdev
+ * # modprobe mvnet
+ * # cd /sys/devices/virtual/mvnet/mvnet/mdev_supported_types/mvnet-virtio
+ * # echo "83b8f4f2-509f-382f-3c1e-e6bfe0fa1001" > ./create
+ * # cd devices/83b8f4f2-509f-382f-3c1e-e6bfe0fa1001
+ * # ls -d virtio0
+ * virtio0
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/uuid.h>
+#include <linux/iommu.h>
+#include <linux/sysfs.h>
+#include <linux/file.h>
+#include <linux/etherdevice.h>
+#include <linux/mdev.h>
+#include <linux/vringh.h>
+#include <linux/virtio_mdev_ops.h>
+#include <uapi/linux/virtio_config.h>
+#include <uapi/linux/virtio_net.h>
+
+#define VERSION_STRING  "0.1"
+#define DRIVER_AUTHOR   "Red Hat Corporation"
+
+#define MVNET_CLASS_NAME "mvnet"
+#define MVNET_NAME       "mvnet"
+
+/*
+ * Global Structures
+ */
+
+static struct mvnet_dev {
+	struct class	*vd_class;
+	struct idr	vd_idr;
+	struct device	dev;
+} mvnet_dev;
+
+struct mvnet_virtqueue {
+	struct vringh vring;
+	struct vringh_kiov iov;
+	unsigned short head;
+	bool ready;
+	u64 desc_addr;
+	u64 device_addr;
+	u64 driver_addr;
+	u32 num;
+	void *private;
+	irqreturn_t (*cb)(void *data);
+};
+
+#define MVNET_QUEUE_ALIGN PAGE_SIZE
+#define MVNET_QUEUE_MAX 256
+#define MVNET_DEVICE_ID 0x1
+#define MVNET_VENDOR_ID 0
+
+u64 mvnet_features = (1ULL << VIRTIO_F_ANY_LAYOUT) |
+		     (1ULL << VIRTIO_F_VERSION_1) |
+		     (1ULL << VIRTIO_F_IOMMU_PLATFORM);
+
+/* State of each mdev device */
+struct mvnet_state {
+	struct mvnet_virtqueue vqs[2];
+	struct work_struct work;
+	spinlock_t lock;
+	struct mdev_device *mdev;
+	struct virtio_net_config config;
+	void *buffer;
+	u32 status;
+	u32 generation;
+	u64 features;
+	struct list_head next;
+};
+
+static struct mutex mdev_list_lock;
+static struct list_head mdev_devices_list;
+
+static void mvnet_queue_ready(struct mvnet_state *mvnet, unsigned int idx)
+{
+	struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+	int ret;
+
+	ret = vringh_init_kern(&vq->vring, mvnet_features, MVNET_QUEUE_MAX,
+			       false, (struct vring_desc *)vq->desc_addr,
+			       (struct vring_avail *)vq->driver_addr,
+			       (struct vring_used *)vq->device_addr);
+}
+
+static void mvnet_vq_reset(struct mvnet_virtqueue *vq)
+{
+	vq->ready = 0;
+	vq->desc_addr = 0;
+	vq->driver_addr = 0;
+	vq->device_addr = 0;
+	vq->cb = NULL;
+	vq->private = NULL;
+	vringh_init_kern(&vq->vring, mvnet_features, MVNET_QUEUE_MAX,
+			false, 0, 0, 0);
+}
+
+static void mvnet_reset(struct mvnet_state *mvnet)
+{
+	int i;
+
+	for (i = 0; i < 2; i++)
+		mvnet_vq_reset(&mvnet->vqs[i]);
+
+	mvnet->features = 0;
+	mvnet->status = 0;
+	++mvnet->generation;
+}
+
+static void mvnet_work(struct work_struct *work)
+{
+	struct mvnet_state *mvnet = container_of(work, struct
+						 mvnet_state, work);
+	struct mvnet_virtqueue *txq = &mvnet->vqs[1];
+	struct mvnet_virtqueue *rxq = &mvnet->vqs[0];
+	size_t read, write, total_write;
+	int err;
+	int pkts = 0;
+
+	spin_lock(&mvnet->lock);
+
+	if (!txq->ready || !rxq->ready)
+		goto out;
+
+	while (true) {
+		total_write = 0;
+		err = vringh_getdesc_kern(&txq->vring, &txq->iov, NULL,
+					  &txq->head, GFP_ATOMIC);
+		if (err <= 0)
+			break;
+
+		err = vringh_getdesc_kern(&rxq->vring, NULL, &rxq->iov,
+					  &rxq->head, GFP_ATOMIC);
+		if (err <= 0) {
+			vringh_complete_kern(&txq->vring, txq->head, 0);
+			break;
+		}
+
+		while (true) {
+			read = vringh_iov_pull_kern(&txq->iov, mvnet->buffer,
+						    PAGE_SIZE);
+			if (read <= 0)
+				break;
+
+			write = vringh_iov_push_kern(&rxq->iov, mvnet->buffer,
+						     read);
+			if (write <= 0)
+				break;
+
+			total_write += write;
+		}
+
+		/* Make sure data is wrote before advancing index */
+		smp_wmb();
+
+		vringh_complete_kern(&txq->vring, txq->head, 0);
+		vringh_complete_kern(&rxq->vring, rxq->head, total_write);
+
+		/* Make sure used is visible before rasing the interrupt. */
+		smp_wmb();
+
+		local_bh_disable();
+		if (txq->cb)
+			txq->cb(txq->private);
+		if (rxq->cb)
+			rxq->cb(rxq->private);
+		local_bh_enable();
+
+		if (++pkts > 4) {
+			schedule_work(&mvnet->work);
+			goto out;
+		}
+	}
+
+out:
+	spin_unlock(&mvnet->lock);
+}
+
+static dma_addr_t mvnet_map_page(struct device *dev, struct page *page,
+				 unsigned long offset, size_t size,
+				 enum dma_data_direction dir,
+				 unsigned long attrs)
+{
+	/* Vringh can only use HVA */
+	return (dma_addr_t)(page_address(page) + offset);
+}
+
+static void mvnet_unmap_page(struct device *dev, dma_addr_t dma_addr,
+			     size_t size, enum dma_data_direction dir,
+			     unsigned long attrs)
+{
+}
+
+static void *mvnet_alloc_coherent(struct device *dev, size_t size,
+				  dma_addr_t *dma_addr, gfp_t flag,
+				  unsigned long attrs)
+{
+	void *addr = kmalloc(size, flag);
+
+	if (addr == NULL)
+		*dma_addr = DMA_MAPPING_ERROR;
+	else
+		*dma_addr = (dma_addr_t) addr;
+
+	return addr;
+}
+
+static void mvnet_free_coherent(struct device *dev, size_t size,
+				void *vaddr, dma_addr_t dma_addr,
+				unsigned long attrs)
+{
+	kfree((void *)dma_addr);
+}
+
+static const struct dma_map_ops mvnet_dma_ops = {
+	.map_page = mvnet_map_page,
+	.unmap_page = mvnet_unmap_page,
+	.alloc = mvnet_alloc_coherent,
+	.free = mvnet_free_coherent,
+};
+
+static const struct virtio_mdev_device_ops virtio_mdev_ops;
+
+static int mvnet_create(struct kobject *kobj, struct mdev_device *mdev)
+{
+	struct mvnet_state *mvnet;
+	struct virtio_net_config *config;
+	struct device *dev = mdev_dev(mdev);
+
+	if (!mdev)
+		return -EINVAL;
+
+	mvnet = kzalloc(sizeof(struct mvnet_state), GFP_KERNEL);
+	if (mvnet == NULL)
+		return -ENOMEM;
+
+	mvnet->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!mvnet->buffer) {
+		kfree(mvnet);
+		return -ENOMEM;
+	}
+
+	config = &mvnet->config;
+	config->mtu = 1500;
+	config->status = VIRTIO_NET_S_LINK_UP;
+	eth_random_addr(config->mac);
+
+	INIT_WORK(&mvnet->work, mvnet_work);
+
+	spin_lock_init(&mvnet->lock);
+	mvnet->mdev = mdev;
+	mdev_set_drvdata(mdev, mvnet);
+
+	mutex_lock(&mdev_list_lock);
+	list_add(&mvnet->next, &mdev_devices_list);
+	mutex_unlock(&mdev_list_lock);
+
+	dev->coherent_dma_mask = DMA_BIT_MASK(64);
+	set_dma_ops(dev, &mvnet_dma_ops);
+
+	mdev_set_virtio_ops(mdev, &virtio_mdev_ops);
+
+	return 0;
+}
+
+static int mvnet_remove(struct mdev_device *mdev)
+{
+	struct mvnet_state *mds, *tmp_mds;
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+	int ret = -EINVAL;
+
+	mutex_lock(&mdev_list_lock);
+	list_for_each_entry_safe(mds, tmp_mds, &mdev_devices_list, next) {
+		if (mvnet == mds) {
+			list_del(&mvnet->next);
+			mdev_set_drvdata(mdev, NULL);
+			kfree(mvnet->buffer);
+			kfree(mvnet);
+			ret = 0;
+			break;
+		}
+	}
+	mutex_unlock(&mdev_list_lock);
+
+	return ret;
+}
+
+static ssize_t
+sample_mvnet_dev_show(struct device *dev, struct device_attribute *attr,
+		     char *buf)
+{
+	if (mdev_from_dev(dev))
+		return sprintf(buf, "This is MDEV %s\n", dev_name(dev));
+
+	return sprintf(buf, "\n");
+}
+
+static DEVICE_ATTR_RO(sample_mvnet_dev);
+
+static struct attribute *mvnet_dev_attrs[] = {
+	&dev_attr_sample_mvnet_dev.attr,
+	NULL,
+};
+
+static const struct attribute_group mvnet_dev_group = {
+	.name  = "mvnet_dev",
+	.attrs = mvnet_dev_attrs,
+};
+
+static const struct attribute_group *mvnet_dev_groups[] = {
+	&mvnet_dev_group,
+	NULL,
+};
+
+static ssize_t
+sample_mdev_dev_show(struct device *dev, struct device_attribute *attr,
+		     char *buf)
+{
+	if (mdev_from_dev(dev))
+		return sprintf(buf, "This is MDEV %s\n", dev_name(dev));
+
+	return sprintf(buf, "\n");
+}
+
+static DEVICE_ATTR_RO(sample_mdev_dev);
+
+static struct attribute *mdev_dev_attrs[] = {
+	&dev_attr_sample_mdev_dev.attr,
+	NULL,
+};
+
+static const struct attribute_group mdev_dev_group = {
+	.name  = "vendor",
+	.attrs = mdev_dev_attrs,
+};
+
+static const struct attribute_group *mdev_dev_groups[] = {
+	&mdev_dev_group,
+	NULL,
+};
+
+#define MVNET_STRING_LEN 16
+
+static ssize_t
+name_show(struct kobject *kobj, struct device *dev, char *buf)
+{
+	char name[MVNET_STRING_LEN];
+	const char *name_str = "virtio-net";
+
+	snprintf(name, MVNET_STRING_LEN, "%s", dev_driver_string(dev));
+	if (!strcmp(kobj->name, name))
+		return sprintf(buf, "%s\n", name_str);
+
+	return -EINVAL;
+}
+
+static MDEV_TYPE_ATTR_RO(name);
+
+static ssize_t
+available_instances_show(struct kobject *kobj, struct device *dev, char *buf)
+{
+	return sprintf(buf, "%d\n", INT_MAX);
+}
+
+static MDEV_TYPE_ATTR_RO(available_instances);
+
+static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
+			       char *buf)
+{
+	return sprintf(buf, "%s\n", VIRTIO_MDEV_DEVICE_API_STRING);
+}
+
+static MDEV_TYPE_ATTR_RO(device_api);
+
+static struct attribute *mdev_types_attrs[] = {
+	&mdev_type_attr_name.attr,
+	&mdev_type_attr_device_api.attr,
+	&mdev_type_attr_available_instances.attr,
+	NULL,
+};
+
+static struct attribute_group mdev_type_group = {
+	.name  = "virtio",
+	.attrs = mdev_types_attrs,
+};
+
+/* TBD: "vhost" type */
+
+static struct attribute_group *mdev_type_groups[] = {
+	&mdev_type_group,
+	NULL,
+};
+
+static int mvnet_set_vq_address(struct mdev_device *mdev, u16 idx,
+				u64 desc_area, u64 driver_area, u64 device_area)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+	struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+
+	vq->desc_addr = desc_area;
+	vq->driver_addr = driver_area;
+	vq->device_addr = device_area;
+
+	return 0;
+}
+
+static void mvnet_set_vq_num(struct mdev_device *mdev, u16 idx, u32 num)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+	struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+
+	vq->num = num;
+}
+
+static void mvnet_kick_vq(struct mdev_device *mdev, u16 idx)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+	struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+
+	if (vq->ready)
+		schedule_work(&mvnet->work);
+}
+
+static void mvnet_set_vq_cb(struct mdev_device *mdev, u16 idx,
+			    struct virtio_mdev_callback *cb)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+	struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+
+	vq->cb = cb->callback;
+	vq->private = cb->private;
+}
+
+static void mvnet_set_vq_ready(struct mdev_device *mdev, u16 idx, bool ready)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+	struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+
+	spin_lock(&mvnet->lock);
+	vq->ready = ready;
+	if (vq->ready)
+		mvnet_queue_ready(mvnet, idx);
+	spin_unlock(&mvnet->lock);
+}
+
+static bool mvnet_get_vq_ready(struct mdev_device *mdev, u16 idx)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+	struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+
+	return vq->ready;
+}
+
+static int mvnet_set_vq_state(struct mdev_device *mdev, u16 idx, u64 state)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+	struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+	struct vringh *vrh = &vq->vring;
+
+	spin_lock(&mvnet->lock);
+	vrh->last_avail_idx = state;
+	spin_unlock(&mvnet->lock);
+
+	return 0;
+}
+
+static u64 mvnet_get_vq_state(struct mdev_device *mdev, u16 idx)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+	struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+	struct vringh *vrh = &vq->vring;
+
+	return vrh->last_avail_idx;
+}
+
+static u16 mvnet_get_vq_align(struct mdev_device *mdev)
+{
+	return MVNET_QUEUE_ALIGN;
+}
+
+static u64 mvnet_get_features(struct mdev_device *mdev)
+{
+	return mvnet_features;
+}
+
+static int mvnet_set_features(struct mdev_device *mdev, u64 features)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+
+	/* DMA mapping must be done by driver */
+	if (!(features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)))
+		return -EINVAL;
+
+	mvnet->features = features & mvnet_features;
+
+	return 0;
+}
+
+static void mvnet_set_config_cb(struct mdev_device *mdev,
+				struct virtio_mdev_callback *cb)
+{
+	/* We don't support config interrupt */
+}
+
+static u16 mvnet_get_vq_num_max(struct mdev_device *mdev)
+{
+	return MVNET_QUEUE_MAX;
+}
+
+static u32 mvnet_get_device_id(struct mdev_device *mdev)
+{
+	return MVNET_DEVICE_ID;
+}
+
+static u32 mvnet_get_vendor_id(struct mdev_device *mdev)
+{
+	return MVNET_VENDOR_ID;
+}
+
+static u8 mvnet_get_status(struct mdev_device *mdev)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+
+	return mvnet->status;
+}
+
+static void mvnet_set_status(struct mdev_device *mdev, u8 status)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+
+	mvnet->status = status;
+
+	if (status == 0) {
+		spin_lock(&mvnet->lock);
+		mvnet_reset(mvnet);
+		spin_unlock(&mvnet->lock);
+	}
+}
+
+static void mvnet_get_config(struct mdev_device *mdev, unsigned int offset,
+			     void *buf, unsigned int len)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+
+	if (offset + len < sizeof(struct virtio_net_config))
+		memcpy(buf, &mvnet->config + offset, len);
+}
+
+static void mvnet_set_config(struct mdev_device *mdev, unsigned int offset,
+			     const void *buf, unsigned int len)
+{
+	/* No writable config supportted by mvnet */
+}
+
+static u64 mvnet_get_mdev_features(struct mdev_device *mdev)
+{
+	return VIRTIO_MDEV_F_VERSION_1;
+}
+
+static u32 mvnet_get_generation(struct mdev_device *mdev)
+{
+	struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+
+	return mvnet->generation;
+}
+
+static const struct virtio_mdev_device_ops virtio_mdev_ops = {
+	.set_vq_address         = mvnet_set_vq_address,
+	.set_vq_num             = mvnet_set_vq_num,
+	.kick_vq                = mvnet_kick_vq,
+	.set_vq_cb              = mvnet_set_vq_cb,
+	.set_vq_ready           = mvnet_set_vq_ready,
+	.get_vq_ready           = mvnet_get_vq_ready,
+	.set_vq_state           = mvnet_set_vq_state,
+	.get_vq_state           = mvnet_get_vq_state,
+	.get_vq_align           = mvnet_get_vq_align,
+	.get_features           = mvnet_get_features,
+	.set_features           = mvnet_set_features,
+	.set_config_cb          = mvnet_set_config_cb,
+	.get_vq_num_max         = mvnet_get_vq_num_max,
+	.get_device_id          = mvnet_get_device_id,
+	.get_vendor_id          = mvnet_get_vendor_id,
+	.get_status             = mvnet_get_status,
+	.set_status             = mvnet_set_status,
+	.get_config             = mvnet_get_config,
+	.set_config             = mvnet_set_config,
+	.get_mdev_features      = mvnet_get_mdev_features,
+	.get_generation         = mvnet_get_generation,
+};
+
+static const struct mdev_parent_ops mdev_fops = {
+	.owner                  = THIS_MODULE,
+	.dev_attr_groups        = mvnet_dev_groups,
+	.mdev_attr_groups       = mdev_dev_groups,
+	.supported_type_groups  = mdev_type_groups,
+	.create                 = mvnet_create,
+	.remove			= mvnet_remove,
+};
+
+static void mvnet_device_release(struct device *dev)
+{
+	dev_dbg(dev, "mvnet: released\n");
+}
+
+static int __init mvnet_dev_init(void)
+{
+	int ret = 0;
+
+	pr_info("mvnet_dev: %s\n", __func__);
+
+	memset(&mvnet_dev, 0, sizeof(mvnet_dev));
+
+	idr_init(&mvnet_dev.vd_idr);
+
+	mvnet_dev.vd_class = class_create(THIS_MODULE, MVNET_CLASS_NAME);
+
+	if (IS_ERR(mvnet_dev.vd_class)) {
+		pr_err("Error: failed to register mvnet_dev class\n");
+		ret = PTR_ERR(mvnet_dev.vd_class);
+		goto failed1;
+	}
+
+	mvnet_dev.dev.class = mvnet_dev.vd_class;
+	mvnet_dev.dev.release = mvnet_device_release;
+	dev_set_name(&mvnet_dev.dev, "%s", MVNET_NAME);
+
+	ret = device_register(&mvnet_dev.dev);
+	if (ret)
+		goto failed2;
+
+	ret = mdev_register_device(&mvnet_dev.dev, &mdev_fops);
+	if (ret)
+		goto failed3;
+
+	mutex_init(&mdev_list_lock);
+	INIT_LIST_HEAD(&mdev_devices_list);
+
+	goto all_done;
+
+failed3:
+
+	device_unregister(&mvnet_dev.dev);
+failed2:
+	class_destroy(mvnet_dev.vd_class);
+
+failed1:
+all_done:
+	return ret;
+}
+
+static void __exit mvnet_dev_exit(void)
+{
+	mvnet_dev.dev.bus = NULL;
+	mdev_unregister_device(&mvnet_dev.dev);
+
+	device_unregister(&mvnet_dev.dev);
+	idr_destroy(&mvnet_dev.vd_idr);
+	class_destroy(mvnet_dev.vd_class);
+	mvnet_dev.vd_class = NULL;
+	pr_info("mvnet_dev: Unloaded!\n");
+}
+
+module_init(mvnet_dev_init)
+module_exit(mvnet_dev_exit)
+
+MODULE_LICENSE("GPL v2");
+MODULE_INFO(supported, "Simulate loopback ethernet device over mdev");
+MODULE_VERSION(VERSION_STRING);
+MODULE_AUTHOR(DRIVER_AUTHOR);
-- 
2.19.1