[PATCH v2 00/13] Remove vfio_mdev.c, mdev_parent_ops and more

[PATCH v2 00/13] Remove vfio_mdev.c, mdev_parent_ops and more

[Jason Gunthorpe]

The mdev bus's core part for managing the lifecycle of devices is mostly
as one would expect for a driver core bus subsystem.

However instead of having a normal 'struct device_driver' and binding the
actual mdev drivers through the standard driver core mechanisms it open
codes this with the struct mdev_parent_ops and provides a single driver
that shims between the VFIO core and the actual device driver.

Make every one of the mdev drivers implement an actual struct mdev_driver
and directly call vfio_register_group_dev() in the probe() function for
the mdev.

Squash what is left of the mdev_parent_ops into the mdev_driver and remap
create(), remove() and mdev_attr_groups to their driver core
equivalents. Arrange to bind the created mdev_device to the mdev_driver
that is provided by the end driver.

The actual execution flow doesn't change much, eg what was
parent_ops->create is now device_driver->probe and it is called at almost
the exact same time - except under the normal control of the driver core.

This allows deleting the entire mdev_drvdata, and tidying some of the
sysfs. Many places in the drivers start using container_of()

This cleanly splits the mdev sysfs GUID lifecycle management stuff from
the vfio_device implementation part, the only VFIO special part of mdev
that remains is the mdev specific iommu intervention.

v2:
 - Keep && m in samples kconfig
 - Restore accidently squashed removeal of vfio_mdev.c
 - Remove indirections to call bus_register()/bus_unregister()
 - Reflow long doc lines
v1: https://lore.kernel.org/r/0-v1-d88406ed308e+418-vfio3_jgg@nvidia.com

Jason

Cc: Leon Romanovsky <leonro@nvidia.com>
Cc: "Raj, Ashok" <ashok.raj@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Max Gurtovoy <mgurtovoy@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Tarun Gupta <targupta@nvidia.com>
Cc: Daniel Vetter <daniel@ffwll.ch>


Jason Gunthorpe (13):
  vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE
  vfio/mdev: Allow the mdev_parent_ops to specify the device driver to
    bind
  vfio/mtty: Convert to use vfio_register_group_dev()
  vfio/mdpy: Convert to use vfio_register_group_dev()
  vfio/mbochs: Convert to use vfio_register_group_dev()
  vfio/ap_ops: Convert to use vfio_register_group_dev()
  vfio/ccw: Convert to use vfio_register_group_dev()
  vfio/gvt: Convert to use vfio_register_group_dev()
  vfio/mdev: Remove vfio_mdev.c
  vfio/mdev: Remove mdev_parent_ops dev_attr_groups
  vfio/mdev: Remove mdev_parent_ops
  vfio/mdev: Use the driver core to create the 'remove' file
  vfio/mdev: Remove mdev drvdata

 .../driver-api/vfio-mediated-device.rst       |  56 ++---
 Documentation/s390/vfio-ap.rst                |   1 -
 arch/s390/Kconfig                             |   2 +-
 drivers/gpu/drm/i915/Kconfig                  |   2 +-
 drivers/gpu/drm/i915/gvt/kvmgt.c              | 210 +++++++++--------
 drivers/s390/cio/vfio_ccw_drv.c               |  21 +-
 drivers/s390/cio/vfio_ccw_ops.c               | 136 ++++++-----
 drivers/s390/cio/vfio_ccw_private.h           |   5 +
 drivers/s390/crypto/vfio_ap_ops.c             | 138 ++++++-----
 drivers/s390/crypto/vfio_ap_private.h         |   2 +
 drivers/vfio/mdev/Kconfig                     |   7 -
 drivers/vfio/mdev/Makefile                    |   1 -
 drivers/vfio/mdev/mdev_core.c                 |  67 ++++--
 drivers/vfio/mdev/mdev_driver.c               |  20 +-
 drivers/vfio/mdev/mdev_private.h              |   4 +-
 drivers/vfio/mdev/mdev_sysfs.c                |  37 ++-
 drivers/vfio/mdev/vfio_mdev.c                 | 180 ---------------
 drivers/vfio/vfio.c                           |   6 +-
 include/linux/mdev.h                          |  86 +------
 include/linux/vfio.h                          |   4 +
 samples/Kconfig                               |   6 +-
 samples/vfio-mdev/mbochs.c                    | 166 +++++++------
 samples/vfio-mdev/mdpy.c                      | 162 +++++++------
 samples/vfio-mdev/mtty.c                      | 218 +++++++-----------
 24 files changed, 651 insertions(+), 886 deletions(-)
 delete mode 100644 drivers/vfio/mdev/vfio_mdev.c

-- 
2.31.1

[PATCH v2 01/13] vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE

[Jason Gunthorpe]

For some reason the vfio_mdev shim mdev_driver has its own module and
kconfig. As the next patch requires access to it from mdev.ko merge the
two modules together and remove VFIO_MDEV_DEVICE.

A later patch deletes this driver entirely.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 Documentation/s390/vfio-ap.rst   |  1 -
 arch/s390/Kconfig                |  2 +-
 drivers/gpu/drm/i915/Kconfig     |  2 +-
 drivers/vfio/mdev/Kconfig        |  7 -------
 drivers/vfio/mdev/Makefile       |  3 +--
 drivers/vfio/mdev/mdev_core.c    | 16 ++++++++++++++--
 drivers/vfio/mdev/mdev_private.h |  2 ++
 drivers/vfio/mdev/vfio_mdev.c    | 24 +-----------------------
 samples/Kconfig                  |  6 +++---
 9 files changed, 23 insertions(+), 40 deletions(-)

diff --git a/Documentation/s390/vfio-ap.rst b/Documentation/s390/vfio-ap.rst
index e15436599086b7..f57ae621f33e89 100644
--- a/Documentation/s390/vfio-ap.rst
+++ b/Documentation/s390/vfio-ap.rst
@@ -514,7 +514,6 @@ These are the steps:
    * S390_AP_IOMMU
    * VFIO
    * VFIO_MDEV
-   * VFIO_MDEV_DEVICE
    * KVM
 
    If using make menuconfig select the following to build the vfio_ap module::
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index c1ff874e6c2e63..dc7928e37fa409 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -773,7 +773,7 @@ config VFIO_CCW
 config VFIO_AP
 	def_tristate n
 	prompt "VFIO support for AP devices"
-	depends on S390_AP_IOMMU && VFIO_MDEV_DEVICE && KVM
+	depends on S390_AP_IOMMU && VFIO_MDEV && KVM
 	depends on ZCRYPT
 	help
 		This driver grants access to Adjunct Processor (AP) devices
diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
index 483e9ff8ca1d23..388bc41aa1a75b 100644
--- a/drivers/gpu/drm/i915/Kconfig
+++ b/drivers/gpu/drm/i915/Kconfig
@@ -125,7 +125,7 @@ config DRM_I915_GVT_KVMGT
 	tristate "Enable KVM/VFIO support for Intel GVT-g"
 	depends on DRM_I915_GVT
 	depends on KVM
-	depends on VFIO_MDEV && VFIO_MDEV_DEVICE
+	depends on VFIO_MDEV
 	default n
 	help
 	  Choose this option if you want to enable KVMGT support for
diff --git a/drivers/vfio/mdev/Kconfig b/drivers/vfio/mdev/Kconfig
index 5da27f2100f9bd..763c877a1318bc 100644
--- a/drivers/vfio/mdev/Kconfig
+++ b/drivers/vfio/mdev/Kconfig
@@ -9,10 +9,3 @@ config VFIO_MDEV
 	  See Documentation/driver-api/vfio-mediated-device.rst for more details.
 
 	  If you don't know what do here, say N.
-
-config VFIO_MDEV_DEVICE
-	tristate "VFIO driver for Mediated devices"
-	depends on VFIO && VFIO_MDEV
-	default n
-	help
-	  VFIO based driver for Mediated devices.
diff --git a/drivers/vfio/mdev/Makefile b/drivers/vfio/mdev/Makefile
index 101516fdf3753e..ff9ecd80212503 100644
--- a/drivers/vfio/mdev/Makefile
+++ b/drivers/vfio/mdev/Makefile
@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
-mdev-y := mdev_core.o mdev_sysfs.o mdev_driver.o
+mdev-y := mdev_core.o mdev_sysfs.o mdev_driver.o vfio_mdev.o
 
 obj-$(CONFIG_VFIO_MDEV) += mdev.o
-obj-$(CONFIG_VFIO_MDEV_DEVICE) += vfio_mdev.o
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 2a85d6fcb7ddd0..ff8c1a84516698 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -360,11 +360,24 @@ int mdev_device_remove(struct mdev_device *mdev)
 
 static int __init mdev_init(void)
 {
-	return mdev_bus_register();
+	int rc;
+
+	rc = mdev_bus_register();
+	if (rc)
+		return rc;
+	rc = mdev_register_driver(&vfio_mdev_driver);
+	if (rc)
+		goto err_bus;
+	return 0;
+err_bus:
+	mdev_bus_unregister();
+	return rc;
 }
 
 static void __exit mdev_exit(void)
 {
+	mdev_unregister_driver(&vfio_mdev_driver);
+
 	if (mdev_bus_compat_class)
 		class_compat_unregister(mdev_bus_compat_class);
 
@@ -378,4 +391,3 @@ MODULE_VERSION(DRIVER_VERSION);
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR(DRIVER_AUTHOR);
 MODULE_DESCRIPTION(DRIVER_DESC);
-MODULE_SOFTDEP("post: vfio_mdev");
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index a656cfe0346c33..5461b67582289f 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -37,6 +37,8 @@ struct mdev_type {
 #define to_mdev_type(_kobj)		\
 	container_of(_kobj, struct mdev_type, kobj)
 
+extern struct mdev_driver vfio_mdev_driver;
+
 int  parent_create_sysfs_files(struct mdev_parent *parent);
 void parent_remove_sysfs_files(struct mdev_parent *parent);
 
diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
index 922729071c5a8e..d5b4eede47c1a5 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -17,10 +17,6 @@
 
 #include "mdev_private.h"
 
-#define DRIVER_VERSION  "0.1"
-#define DRIVER_AUTHOR   "NVIDIA Corporation"
-#define DRIVER_DESC     "VFIO based driver for Mediated device"
-
 static int vfio_mdev_open(struct vfio_device *core_vdev)
 {
 	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
@@ -151,7 +147,7 @@ static void vfio_mdev_remove(struct mdev_device *mdev)
 	kfree(vdev);
 }
 
-static struct mdev_driver vfio_mdev_driver = {
+struct mdev_driver vfio_mdev_driver = {
 	.driver = {
 		.name = "vfio_mdev",
 		.owner = THIS_MODULE,
@@ -160,21 +156,3 @@ static struct mdev_driver vfio_mdev_driver = {
 	.probe	= vfio_mdev_probe,
 	.remove	= vfio_mdev_remove,
 };
-
-static int __init vfio_mdev_init(void)
-{
-	return mdev_register_driver(&vfio_mdev_driver);
-}
-
-static void __exit vfio_mdev_exit(void)
-{
-	mdev_unregister_driver(&vfio_mdev_driver);
-}
-
-module_init(vfio_mdev_init)
-module_exit(vfio_mdev_exit)
-
-MODULE_VERSION(DRIVER_VERSION);
-MODULE_LICENSE("GPL v2");
-MODULE_AUTHOR(DRIVER_AUTHOR);
-MODULE_DESCRIPTION(DRIVER_DESC);
diff --git a/samples/Kconfig b/samples/Kconfig
index e76cdfc50e257d..5708abcc55c4df 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -147,14 +147,14 @@ config SAMPLE_UHID
 
 config SAMPLE_VFIO_MDEV_MTTY
 	tristate "Build VFIO mtty example mediated device sample code -- loadable modules only"
-	depends on VFIO_MDEV_DEVICE && m
+	depends on VFIO_MDEV && m
 	help
 	  Build a virtual tty sample driver for use as a VFIO
 	  mediated device
 
 config SAMPLE_VFIO_MDEV_MDPY
 	tristate "Build VFIO mdpy example mediated device sample code -- loadable modules only"
-	depends on VFIO_MDEV_DEVICE && m
+	depends on VFIO_MDEV && m
 	help
 	  Build a virtual display sample driver for use as a VFIO
 	  mediated device.  It is a simple framebuffer and supports
@@ -171,7 +171,7 @@ config SAMPLE_VFIO_MDEV_MDPY_FB
 
 config SAMPLE_VFIO_MDEV_MBOCHS
 	tristate "Build VFIO mdpy example mediated device sample code -- loadable modules only"
-	depends on VFIO_MDEV_DEVICE && m
+	depends on VFIO_MDEV && m
 	select DMA_SHARED_BUFFER
 	help
 	  Build a virtual display sample driver for use as a VFIO
-- 
2.31.1

[PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

[Jason Gunthorpe]

Now that all mdev drivers directly create their own mdev_device driver and
directly register with the vfio core's vfio_device_ops this is all dead
code.

Delete vfio_mdev.c and the mdev_parent_ops members that are connected to
it.

Preserve VFIO's design of allowing mdev drivers to be !GPL by allowing the
three functions that replace this module for !GPL usage. This goes along
with the other 19 symbols that are already marked !GPL in VFIO.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 .../driver-api/vfio-mediated-device.rst       |  19 ---
 drivers/vfio/mdev/Makefile                    |   2 +-
 drivers/vfio/mdev/mdev_core.c                 |  49 +-----
 drivers/vfio/mdev/mdev_driver.c               |  21 +--
 drivers/vfio/mdev/mdev_private.h              |   2 -
 drivers/vfio/mdev/vfio_mdev.c                 | 158 ------------------
 drivers/vfio/vfio.c                           |   6 +-
 include/linux/mdev.h                          |  52 ------
 include/linux/vfio.h                          |   4 +
 9 files changed, 16 insertions(+), 297 deletions(-)
 delete mode 100644 drivers/vfio/mdev/vfio_mdev.c

diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
index 1779b85f014e2f..5f866b17c93e69 100644
--- a/Documentation/driver-api/vfio-mediated-device.rst
+++ b/Documentation/driver-api/vfio-mediated-device.rst
@@ -137,25 +137,6 @@ The structures in the mdev_parent_ops structure are as follows:
 * mdev_attr_groups: attributes of the mediated device
 * supported_config: attributes to define supported configurations
 
-The functions in the mdev_parent_ops structure are as follows:
-
-* create: allocate basic resources in a driver for a mediated device
-* remove: free resources in a driver when a mediated device is destroyed
-
-(Note that mdev-core provides no implicit serialization of create/remove
-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::
 
diff --git a/drivers/vfio/mdev/Makefile b/drivers/vfio/mdev/Makefile
index ff9ecd80212503..7c236ba1b90eb1 100644
--- a/drivers/vfio/mdev/Makefile
+++ b/drivers/vfio/mdev/Makefile
@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
-mdev-y := mdev_core.o mdev_sysfs.o mdev_driver.o vfio_mdev.o
+mdev-y := mdev_core.o mdev_sysfs.o mdev_driver.o
 
 obj-$(CONFIG_VFIO_MDEV) += mdev.o
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 51b8a9fcf866ad..d507047e6ecf4a 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -89,17 +89,10 @@ void mdev_release_parent(struct kref *kref)
 static void mdev_device_remove_common(struct mdev_device *mdev)
 {
 	struct mdev_parent *parent = mdev->type->parent;
-	int ret;
 
 	mdev_remove_sysfs_files(mdev);
 	device_del(&mdev->dev);
 	lockdep_assert_held(&parent->unreg_sem);
-	if (parent->ops->remove) {
-		ret = parent->ops->remove(mdev);
-		if (ret)
-			dev_err(&mdev->dev, "Remove failed: err=%d\n", ret);
-	}
-
 	/* Balances with device_initialize() */
 	put_device(&mdev->dev);
 }
@@ -131,17 +124,13 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
 	/* check for mandatory ops */
 	if (!ops || !ops->supported_type_groups)
 		return -EINVAL;
-	if (!ops->device_driver && (!ops->create || !ops->remove))
+	if (!ops->device_driver)
 		return -EINVAL;
 
 	dev = get_device(dev);
 	if (!dev)
 		return -EINVAL;
 
-	/* Not mandatory, but its absence could be a problem */
-	if (!ops->request)
-		dev_info(dev, "Driver cannot be asked to release device\n");
-
 	mutex_lock(&parent_list_lock);
 
 	/* Check for duplicate */
@@ -263,15 +252,12 @@ static void mdev_device_release(struct device *dev)
  */
 static int mdev_bind_driver(struct mdev_device *mdev)
 {
-	struct mdev_driver *drv = mdev->type->parent->ops->device_driver;
 	int ret;
 
-	if (!drv)
-		drv = &vfio_mdev_driver;
-
 	while (1) {
 		device_lock(&mdev->dev);
-		if (mdev->dev.driver == &drv->driver) {
+		if (mdev->dev.driver ==
+		    &mdev->type->parent->ops->device_driver->driver) {
 			ret = 0;
 			goto out_unlock;
 		}
@@ -337,15 +323,9 @@ int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
 		goto out_put_device;
 	}
 
-	if (parent->ops->create) {
-		ret = parent->ops->create(mdev);
-		if (ret)
-			goto out_unlock;
-	}
-
 	ret = device_add(&mdev->dev);
 	if (ret)
-		goto out_remove;
+		goto out_unlock;
 
 	ret = mdev_bind_driver(mdev);
 	if (ret)
@@ -363,9 +343,6 @@ int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
 
 out_del:
 	device_del(&mdev->dev);
-out_remove:
-	if (parent->ops->remove)
-		parent->ops->remove(mdev);
 out_unlock:
 	up_read(&parent->unreg_sem);
 out_put_device:
@@ -408,28 +385,14 @@ int mdev_device_remove(struct mdev_device *mdev)
 
 static int __init mdev_init(void)
 {
-	int rc;
-
-	rc = mdev_bus_register();
-	if (rc)
-		return rc;
-	rc = mdev_register_driver(&vfio_mdev_driver);
-	if (rc)
-		goto err_bus;
-	return 0;
-err_bus:
-	mdev_bus_unregister();
-	return rc;
+	return bus_register(&mdev_bus_type);
 }
 
 static void __exit mdev_exit(void)
 {
-	mdev_unregister_driver(&vfio_mdev_driver);
-
 	if (mdev_bus_compat_class)
 		class_compat_unregister(mdev_bus_compat_class);
-
-	mdev_bus_unregister();
+	bus_unregister(&mdev_bus_type);
 }
 
 module_init(mdev_init)
diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
index 6e96c023d7823d..07ada55efd6228 100644
--- a/drivers/vfio/mdev/mdev_driver.c
+++ b/drivers/vfio/mdev/mdev_driver.c
@@ -74,15 +74,8 @@ static int mdev_remove(struct device *dev)
 static int mdev_match(struct device *dev, struct device_driver *drv)
 {
 	struct mdev_device *mdev = to_mdev_device(dev);
-	struct mdev_driver *target = mdev->type->parent->ops->device_driver;
-
-	/*
-	 * The ops specify the device driver to connect, fall back to the old
-	 * shim driver if the driver hasn't been converted.
-	 */
-	if (!target)
-		target = &vfio_mdev_driver;
-	return drv == &target->driver;
+
+	return drv == &mdev->type->parent->ops->device_driver->driver;
 }
 
 struct bus_type mdev_bus_type = {
@@ -118,13 +111,3 @@ void mdev_unregister_driver(struct mdev_driver *drv)
 	driver_unregister(&drv->driver);
 }
 EXPORT_SYMBOL(mdev_unregister_driver);
-
-int mdev_bus_register(void)
-{
-	return bus_register(&mdev_bus_type);
-}
-
-void mdev_bus_unregister(void)
-{
-	bus_unregister(&mdev_bus_type);
-}
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index 5461b67582289f..a656cfe0346c33 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -37,8 +37,6 @@ struct mdev_type {
 #define to_mdev_type(_kobj)		\
 	container_of(_kobj, struct mdev_type, kobj)
 
-extern struct mdev_driver vfio_mdev_driver;
-
 int  parent_create_sysfs_files(struct mdev_parent *parent);
 void parent_remove_sysfs_files(struct mdev_parent *parent);
 
diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
deleted file mode 100644
index d5b4eede47c1a5..00000000000000
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ /dev/null
@@ -1,158 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * VFIO based driver for Mediated device
- *
- * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
- *     Author: Neo Jia <cjia@nvidia.com>
- *             Kirti Wankhede <kwankhede@nvidia.com>
- */
-
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/device.h>
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/vfio.h>
-#include <linux/mdev.h>
-
-#include "mdev_private.h"
-
-static int vfio_mdev_open(struct vfio_device *core_vdev)
-{
-	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
-	struct mdev_parent *parent = mdev->type->parent;
-
-	int ret;
-
-	if (unlikely(!parent->ops->open))
-		return -EINVAL;
-
-	if (!try_module_get(THIS_MODULE))
-		return -ENODEV;
-
-	ret = parent->ops->open(mdev);
-	if (ret)
-		module_put(THIS_MODULE);
-
-	return ret;
-}
-
-static void vfio_mdev_release(struct vfio_device *core_vdev)
-{
-	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
-	struct mdev_parent *parent = mdev->type->parent;
-
-	if (likely(parent->ops->release))
-		parent->ops->release(mdev);
-
-	module_put(THIS_MODULE);
-}
-
-static long vfio_mdev_unlocked_ioctl(struct vfio_device *core_vdev,
-				     unsigned int cmd, unsigned long arg)
-{
-	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
-	struct mdev_parent *parent = mdev->type->parent;
-
-	if (unlikely(!parent->ops->ioctl))
-		return -EINVAL;
-
-	return parent->ops->ioctl(mdev, cmd, arg);
-}
-
-static ssize_t vfio_mdev_read(struct vfio_device *core_vdev, char __user *buf,
-			      size_t count, loff_t *ppos)
-{
-	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
-	struct mdev_parent *parent = mdev->type->parent;
-
-	if (unlikely(!parent->ops->read))
-		return -EINVAL;
-
-	return parent->ops->read(mdev, buf, count, ppos);
-}
-
-static ssize_t vfio_mdev_write(struct vfio_device *core_vdev,
-			       const char __user *buf, size_t count,
-			       loff_t *ppos)
-{
-	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
-	struct mdev_parent *parent = mdev->type->parent;
-
-	if (unlikely(!parent->ops->write))
-		return -EINVAL;
-
-	return parent->ops->write(mdev, buf, count, ppos);
-}
-
-static int vfio_mdev_mmap(struct vfio_device *core_vdev,
-			  struct vm_area_struct *vma)
-{
-	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
-	struct mdev_parent *parent = mdev->type->parent;
-
-	if (unlikely(!parent->ops->mmap))
-		return -EINVAL;
-
-	return parent->ops->mmap(mdev, vma);
-}
-
-static void vfio_mdev_request(struct vfio_device *core_vdev, unsigned int count)
-{
-	struct mdev_device *mdev = to_mdev_device(core_vdev->dev);
-	struct mdev_parent *parent = mdev->type->parent;
-
-	if (parent->ops->request)
-		parent->ops->request(mdev, count);
-	else if (count == 0)
-		dev_notice(mdev_dev(mdev),
-			   "No mdev vendor driver request callback support, blocked until released by user\n");
-}
-
-static const struct vfio_device_ops vfio_mdev_dev_ops = {
-	.name		= "vfio-mdev",
-	.open		= vfio_mdev_open,
-	.release	= vfio_mdev_release,
-	.ioctl		= vfio_mdev_unlocked_ioctl,
-	.read		= vfio_mdev_read,
-	.write		= vfio_mdev_write,
-	.mmap		= vfio_mdev_mmap,
-	.request	= vfio_mdev_request,
-};
-
-static int vfio_mdev_probe(struct mdev_device *mdev)
-{
-	struct vfio_device *vdev;
-	int ret;
-
-	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
-	if (!vdev)
-		return -ENOMEM;
-
-	vfio_init_group_dev(vdev, &mdev->dev, &vfio_mdev_dev_ops);
-	ret = vfio_register_group_dev(vdev);
-	if (ret) {
-		kfree(vdev);
-		return ret;
-	}
-	dev_set_drvdata(&mdev->dev, vdev);
-	return 0;
-}
-
-static void vfio_mdev_remove(struct mdev_device *mdev)
-{
-	struct vfio_device *vdev = dev_get_drvdata(&mdev->dev);
-
-	vfio_unregister_group_dev(vdev);
-	kfree(vdev);
-}
-
-struct mdev_driver vfio_mdev_driver = {
-	.driver = {
-		.name = "vfio_mdev",
-		.owner = THIS_MODULE,
-		.mod_name = KBUILD_MODNAME,
-	},
-	.probe	= vfio_mdev_probe,
-	.remove	= vfio_mdev_remove,
-};
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 5e631c359ef23c..59bbdf6634f934 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -747,7 +747,7 @@ void vfio_init_group_dev(struct vfio_device *device, struct device *dev,
 	device->dev = dev;
 	device->ops = ops;
 }
-EXPORT_SYMBOL_GPL(vfio_init_group_dev);
+EXPORT_SYMBOL(vfio_init_group_dev);
 
 int vfio_register_group_dev(struct vfio_device *device)
 {
@@ -796,7 +796,7 @@ int vfio_register_group_dev(struct vfio_device *device)
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(vfio_register_group_dev);
+EXPORT_SYMBOL(vfio_register_group_dev);
 
 /**
  * Get a reference to the vfio_device for a device.  Even if the
@@ -927,7 +927,7 @@ void vfio_unregister_group_dev(struct vfio_device *device)
 	/* Matches the get in vfio_register_group_dev() */
 	vfio_group_put(group);
 }
-EXPORT_SYMBOL_GPL(vfio_unregister_group_dev);
+EXPORT_SYMBOL(vfio_unregister_group_dev);
 
 /**
  * VFIO base fd, /dev/vfio/vfio
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index 49cc4f65120d57..ea48c401e4fa63 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -61,45 +61,6 @@ struct device *mtype_get_parent_dev(struct mdev_type *mtype);
  * @mdev_attr_groups:	Attributes of the mediated device.
  * @supported_type_groups: Attributes to define supported types. It is mandatory
  *			to provide supported types.
- * @create:		Called to allocate basic resources in parent device's
- *			driver for a particular mediated device. It is
- *			mandatory to provide create ops.
- *			@mdev: mdev_device structure on of mediated device
- *			      that is being created
- *			Returns integer: success (0) or error (< 0)
- * @remove:		Called to free resources in parent device's driver for
- *			a mediated device. It is mandatory to provide 'remove'
- *			ops.
- *			@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
- * @request:		request callback to release device
- *			@mdev: mediated device structure
- *			@count: request sequence number
  * Parent device that support mediated device should be registered with mdev
  * module with mdev_parent_ops structure.
  **/
@@ -109,19 +70,6 @@ struct mdev_parent_ops {
 	const struct attribute_group **dev_attr_groups;
 	const struct attribute_group **mdev_attr_groups;
 	struct attribute_group **supported_type_groups;
-
-	int     (*create)(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);
-	void	(*request)(struct mdev_device *mdev, unsigned int count);
 };
 
 /* interface for exporting mdev supported type attributes */
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index a2c5b30e1763ba..c5e08be4c56395 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -64,6 +64,10 @@ void vfio_init_group_dev(struct vfio_device *device, struct device *dev,
 int vfio_register_group_dev(struct vfio_device *device);
 void vfio_unregister_group_dev(struct vfio_device *device);
 extern struct vfio_device *vfio_device_get_from_dev(struct device *dev);
+static inline void vfio_device_get(struct vfio_device *device)
+{
+	refcount_inc(&device->refcount);
+}
 extern void vfio_device_put(struct vfio_device *device);
 
 /* events for the backend driver notify callback */
-- 
2.31.1

[PATCH v2 11/13] vfio/mdev: Remove mdev_parent_ops

[Jason Gunthorpe]

The last useful member in this struct is the supported_type_groups, move
it to the mdev_driver and delete mdev_parent_ops.

Replace it with mdev_driver as an argument to mdev_register_device()

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 .../driver-api/vfio-mediated-device.rst       | 37 +++++++------------
 drivers/gpu/drm/i915/gvt/kvmgt.c              |  8 +---
 drivers/s390/cio/vfio_ccw_ops.c               |  7 +---
 drivers/s390/crypto/vfio_ap_ops.c             |  9 +----
 drivers/vfio/mdev/mdev_core.c                 | 13 +++----
 drivers/vfio/mdev/mdev_driver.c               |  2 +-
 drivers/vfio/mdev/mdev_private.h              |  2 +-
 drivers/vfio/mdev/mdev_sysfs.c                |  6 +--
 include/linux/mdev.h                          | 24 ++----------
 samples/vfio-mdev/mbochs.c                    |  9 +----
 samples/vfio-mdev/mdpy.c                      |  9 +----
 samples/vfio-mdev/mtty.c                      |  9 +----
 12 files changed, 39 insertions(+), 96 deletions(-)

diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst
index 5f866b17c93e69..a073d0bb06e7fd 100644
--- a/Documentation/driver-api/vfio-mediated-device.rst
+++ b/Documentation/driver-api/vfio-mediated-device.rst
@@ -93,7 +93,7 @@ interfaces:
 Registration Interface for a Mediated Bus Driver
 ------------------------------------------------
 
-The registration interface for a mediated bus driver provides the following
+The registration interface for a mediated device driver provides the following
 structure to represent a mediated device's driver::
 
      /*
@@ -105,6 +105,7 @@ structure to represent a mediated device's driver::
      struct mdev_driver {
 	     int  (*probe)  (struct mdev_device *dev);
 	     void (*remove) (struct mdev_device *dev);
+	     struct attribute_group **supported_type_groups;
 	     struct device_driver    driver;
      };
 
@@ -119,35 +120,25 @@ to register and unregister itself with the core driver:
 
     extern void mdev_unregister_driver(struct mdev_driver *drv);
 
-The mediated bus driver is responsible for adding mediated devices to the VFIO
-group when devices are bound to the driver and removing mediated devices from
-the VFIO when devices are unbound from the driver.
+The mediated bus driver's probe function should create a vfio_device on top of
+the mdev_device and connect it to an appropriate implementation of
+vfio_device_ops.
 
-
-Physical Device Driver Interface
---------------------------------
-
-The physical device driver interface provides the mdev_parent_ops[3] structure
-to define the APIs to manage work in the mediated core driver that is related
-to the physical device.
-
-The structures in the mdev_parent_ops structure are as follows:
-
-* dev_attr_groups: attributes of the parent device
-* mdev_attr_groups: attributes of the mediated device
-* supported_config: attributes to define supported configurations
-
-A driver should use the mdev_parent_ops structure in the function call to
-register itself with the mdev core driver::
+When a driver wants to add the GUID creation sysfs to an existing device it has
+probe'd to then it should call:
 
 	extern int  mdev_register_device(struct device *dev,
-	                                 const struct mdev_parent_ops *ops);
+	                                 struct mdev_driver *mdev_driver);
+
+This will provide the 'mdev_supported_types/XX/create' files which can then be
+used to trigger the creation of a mdev_device. The created mdev_device will be
+attached to the specified driver.
 
-However, the mdev_parent_ops structure is not required in the function call
-that a driver should use to unregister itself with the mdev core driver::
+When the driver needs to remove itself it calls:
 
 	extern void mdev_unregister_device(struct device *dev);
 
+Which will unbind and destroy all the created mdevs and remove the sysfs files.
 
 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 85ef300087e091..02089efd15bb92 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -1669,10 +1669,6 @@ static struct mdev_driver intel_vgpu_mdev_driver = {
 	.remove	= intel_vgpu_remove,
 };
 
-static struct mdev_parent_ops intel_vgpu_ops = {
-	.device_driver		= &intel_vgpu_mdev_driver,
-};
-
 static int kvmgt_host_init(struct device *dev, void *gvt, const void *ops)
 {
 	struct attribute_group **kvm_vgpu_type_groups;
@@ -1680,9 +1676,9 @@ static int kvmgt_host_init(struct device *dev, void *gvt, const void *ops)
 	intel_gvt_ops = ops;
 	if (!intel_gvt_ops->get_gvt_attrs(&kvm_vgpu_type_groups))
 		return -EFAULT;
-	intel_vgpu_ops.supported_type_groups = kvm_vgpu_type_groups;
+	intel_vgpu_mdev_driver.supported_type_groups = kvm_vgpu_type_groups;
 
-	return mdev_register_device(dev, &intel_vgpu_ops);
+	return mdev_register_device(dev, &intel_vgpu_mdev_driver);
 }
 
 static void kvmgt_host_exit(struct device *dev)
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 0fcf46031d3821..161697529dcc41 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -655,17 +655,12 @@ struct mdev_driver vfio_ccw_mdev_driver = {
 	},
 	.probe = vfio_ccw_mdev_probe,
 	.remove = vfio_ccw_mdev_remove,
-};
-
-static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
-	.owner			= THIS_MODULE,
-	.device_driver		= &vfio_ccw_mdev_driver,
 	.supported_type_groups  = mdev_type_groups,
 };
 
 int vfio_ccw_mdev_reg(struct subchannel *sch)
 {
-	return mdev_register_device(&sch->dev, &vfio_ccw_mdev_ops);
+	return mdev_register_device(&sch->dev, &vfio_ccw_mdev_driver);
 }
 
 void vfio_ccw_mdev_unreg(struct subchannel *sch)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 79872c857dd522..92789257c87639 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1339,12 +1339,7 @@ static struct mdev_driver vfio_ap_matrix_driver = {
 	},
 	.probe = vfio_ap_mdev_probe,
 	.remove = vfio_ap_mdev_remove,
-};
-
-static const struct mdev_parent_ops vfio_ap_matrix_ops = {
-	.owner			= THIS_MODULE,
-	.device_driver		= &vfio_ap_matrix_driver,
-	.supported_type_groups	= vfio_ap_mdev_type_groups,
+	.supported_type_groups = vfio_ap_mdev_type_groups,
 };
 
 int vfio_ap_mdev_register(void)
@@ -1357,7 +1352,7 @@ int vfio_ap_mdev_register(void)
 	if (ret)
 		return ret;
 
-	ret = mdev_register_device(&matrix_dev->device, &vfio_ap_matrix_ops);
+	ret = mdev_register_device(&matrix_dev->device, &vfio_ap_matrix_driver);
 	if (ret)
 		goto err_driver;
 	return 0;
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index d507047e6ecf4a..cd1ab9fe299445 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -109,12 +109,12 @@ 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.
+ * @mdev_driver: Device driver to bind to the newly created mdev
  *
  * Add device to list of registered parent devices.
  * Returns a negative value on error, otherwise 0.
  */
-int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
+int mdev_register_device(struct device *dev, struct mdev_driver *mdev_driver)
 {
 	int ret;
 	struct mdev_parent *parent;
@@ -122,9 +122,7 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
 	char *envp[] = { env_string, NULL };
 
 	/* check for mandatory ops */
-	if (!ops || !ops->supported_type_groups)
-		return -EINVAL;
-	if (!ops->device_driver)
+	if (!mdev_driver->supported_type_groups)
 		return -EINVAL;
 
 	dev = get_device(dev);
@@ -151,7 +149,7 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
 	init_rwsem(&parent->unreg_sem);
 
 	parent->dev = dev;
-	parent->ops = ops;
+	parent->mdev_driver = mdev_driver;
 
 	if (!mdev_bus_compat_class) {
 		mdev_bus_compat_class = class_compat_register("mdev_bus");
@@ -257,7 +255,7 @@ static int mdev_bind_driver(struct mdev_device *mdev)
 	while (1) {
 		device_lock(&mdev->dev);
 		if (mdev->dev.driver ==
-		    &mdev->type->parent->ops->device_driver->driver) {
+		    &mdev->type->parent->mdev_driver->driver) {
 			ret = 0;
 			goto out_unlock;
 		}
@@ -304,7 +302,6 @@ int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
 	mdev->dev.parent  = parent->dev;
 	mdev->dev.bus = &mdev_bus_type;
 	mdev->dev.release = mdev_device_release;
-	mdev->dev.groups = parent->ops->mdev_attr_groups;
 	mdev->type = type;
 	/* Pairs with the put in mdev_device_release() */
 	kobject_get(&type->kobj);
diff --git a/drivers/vfio/mdev/mdev_driver.c b/drivers/vfio/mdev/mdev_driver.c
index 07ada55efd6228..d743a9f51f4c90 100644
--- a/drivers/vfio/mdev/mdev_driver.c
+++ b/drivers/vfio/mdev/mdev_driver.c
@@ -75,7 +75,7 @@ static int mdev_match(struct device *dev, struct device_driver *drv)
 {
 	struct mdev_device *mdev = to_mdev_device(dev);
 
-	return drv == &mdev->type->parent->ops->device_driver->driver;
+	return drv == &mdev->type->parent->mdev_driver->driver;
 }
 
 struct bus_type mdev_bus_type = {
diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
index a656cfe0346c33..839567d059a07d 100644
--- a/drivers/vfio/mdev/mdev_private.h
+++ b/drivers/vfio/mdev/mdev_private.h
@@ -15,7 +15,7 @@ void mdev_bus_unregister(void);
 
 struct mdev_parent {
 	struct device *dev;
-	const struct mdev_parent_ops *ops;
+	const struct mdev_driver *mdev_driver;
 	struct kref ref;
 	struct list_head next;
 	struct kset *mdev_types_kset;
diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
index 66eef08833a4ef..5a3873d1a275ae 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -97,7 +97,7 @@ static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
 {
 	struct mdev_type *type;
 	struct attribute_group *group =
-		parent->ops->supported_type_groups[type_group_id];
+		parent->mdev_driver->supported_type_groups[type_group_id];
 	int ret;
 
 	if (!group->name) {
@@ -154,7 +154,7 @@ static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
 static void remove_mdev_supported_type(struct mdev_type *type)
 {
 	struct attribute_group *group =
-		type->parent->ops->supported_type_groups[type->type_group_id];
+		type->parent->mdev_driver->supported_type_groups[type->type_group_id];
 
 	sysfs_remove_files(&type->kobj,
 			   (const struct attribute **)group->attrs);
@@ -168,7 +168,7 @@ static int add_mdev_supported_type_groups(struct mdev_parent *parent)
 {
 	int i;
 
-	for (i = 0; parent->ops->supported_type_groups[i]; i++) {
+	for (i = 0; parent->mdev_driver->supported_type_groups[i]; i++) {
 		struct mdev_type *type;
 
 		type = add_mdev_supported_type(parent, i);
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index fd9fe1dcf0e230..af807c77c1e0f5 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -51,25 +51,6 @@ unsigned int mdev_get_type_group_id(struct mdev_device *mdev);
 unsigned int mtype_get_type_group_id(struct mdev_type *mtype);
 struct device *mtype_get_parent_dev(struct mdev_type *mtype);
 
-/**
- * struct mdev_parent_ops - Structure to be registered for each parent device to
- * register the device to mdev module.
- *
- * @owner:		The module owner.
- * @device_driver:	Which device driver to probe() on newly created devices
- * @mdev_attr_groups:	Attributes of the mediated device.
- * @supported_type_groups: Attributes to define supported types. It is mandatory
- *			to provide supported types.
- * Parent device that support mediated device should be registered with mdev
- * module with mdev_parent_ops structure.
- **/
-struct mdev_parent_ops {
-	struct module   *owner;
-	struct mdev_driver *device_driver;
-	const struct attribute_group **mdev_attr_groups;
-	struct attribute_group **supported_type_groups;
-};
-
 /* interface for exporting mdev supported type attributes */
 struct mdev_type_attribute {
 	struct attribute attr;
@@ -94,12 +75,15 @@ struct mdev_type_attribute mdev_type_attr_##_name =		\
  * struct mdev_driver - Mediated device driver
  * @probe: called when new device created
  * @remove: called when device removed
+ * @supported_type_groups: Attributes to define supported types. It is mandatory
+ *			to provide supported types.
  * @driver: device driver structure
  *
  **/
 struct mdev_driver {
 	int (*probe)(struct mdev_device *dev);
 	void (*remove)(struct mdev_device *dev);
+	struct attribute_group **supported_type_groups;
 	struct device_driver driver;
 };
 
@@ -118,7 +102,7 @@ static inline const guid_t *mdev_uuid(struct mdev_device *mdev)
 
 extern struct bus_type mdev_bus_type;
 
-int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops);
+int mdev_register_device(struct device *dev, struct mdev_driver *mdev_driver);
 void mdev_unregister_device(struct device *dev);
 
 int mdev_register_driver(struct mdev_driver *drv);
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index e18821a8a6beb8..c76ceec584b41b 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -1418,12 +1418,7 @@ static struct mdev_driver mbochs_driver = {
 	},
 	.probe = mbochs_probe,
 	.remove	= mbochs_remove,
-};
-
-static const struct mdev_parent_ops mdev_fops = {
-	.owner			= THIS_MODULE,
-	.device_driver		= &mbochs_driver,
-	.supported_type_groups	= mdev_type_groups,
+	.supported_type_groups = mdev_type_groups,
 };
 
 static const struct file_operations vd_fops = {
@@ -1466,7 +1461,7 @@ static int __init mbochs_dev_init(void)
 	if (ret)
 		goto err_class;
 
-	ret = mdev_register_device(&mbochs_dev, &mdev_fops);
+	ret = mdev_register_device(&mbochs_dev, &mbochs_driver);
 	if (ret)
 		goto err_device;
 
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index 82638de333330d..c22b2c808d132d 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -735,12 +735,7 @@ static struct mdev_driver mdpy_driver = {
 	},
 	.probe = mdpy_probe,
 	.remove	= mdpy_remove,
-};
-
-static const struct mdev_parent_ops mdev_fops = {
-	.owner			= THIS_MODULE,
-	.device_driver          = &mdpy_driver,
-	.supported_type_groups	= mdev_type_groups,
+	.supported_type_groups = mdev_type_groups,
 };
 
 static const struct file_operations vd_fops = {
@@ -783,7 +778,7 @@ static int __init mdpy_dev_init(void)
 	if (ret)
 		goto err_class;
 
-	ret = mdev_register_device(&mdpy_dev, &mdev_fops);
+	ret = mdev_register_device(&mdpy_dev, &mdpy_driver);
 	if (ret)
 		goto err_device;
 
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 31eec76bc553ce..87f5ba12a230e3 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -1308,12 +1308,7 @@ static struct mdev_driver mtty_driver = {
 	},
 	.probe = mtty_probe,
 	.remove	= mtty_remove,
-};
-
-static const struct mdev_parent_ops mdev_fops = {
-	.owner                  = THIS_MODULE,
-	.device_driver		= &mtty_driver,
-	.supported_type_groups  = mdev_type_groups,
+	.supported_type_groups = mdev_type_groups,
 };
 
 static void mtty_device_release(struct device *dev)
@@ -1364,7 +1359,7 @@ static int __init mtty_dev_init(void)
 	if (ret)
 		goto err_class;
 
-	ret = mdev_register_device(&mtty_dev.dev, &mdev_fops);
+	ret = mdev_register_device(&mtty_dev.dev, &mtty_driver);
 	if (ret)
 		goto err_device;
 
-- 
2.31.1

Re: [PATCH v2 01/13] vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE

[Cornelia Huck]

On Mon, 26 Apr 2021 17:00:03 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> For some reason the vfio_mdev shim mdev_driver has its own module and
> kconfig. As the next patch requires access to it from mdev.ko merge the
> two modules together and remove VFIO_MDEV_DEVICE.
> 
> A later patch deletes this driver entirely.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>  Documentation/s390/vfio-ap.rst   |  1 -
>  arch/s390/Kconfig                |  2 +-
>  drivers/gpu/drm/i915/Kconfig     |  2 +-
>  drivers/vfio/mdev/Kconfig        |  7 -------
>  drivers/vfio/mdev/Makefile       |  3 +--
>  drivers/vfio/mdev/mdev_core.c    | 16 ++++++++++++++--
>  drivers/vfio/mdev/mdev_private.h |  2 ++
>  drivers/vfio/mdev/vfio_mdev.c    | 24 +-----------------------
>  samples/Kconfig                  |  6 +++---
>  9 files changed, 23 insertions(+), 40 deletions(-)

This also fixes the dependencies for vfio-ccw, which never depended on
VFIO_MDEV_DEVICE directly...

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [PATCH v2 00/13] Remove vfio_mdev.c, mdev_parent_ops and more

[Alex Williamson]

On Mon, 26 Apr 2021 17:00:02 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> The mdev bus's core part for managing the lifecycle of devices is mostly
> as one would expect for a driver core bus subsystem.
> 
> However instead of having a normal 'struct device_driver' and binding the
> actual mdev drivers through the standard driver core mechanisms it open
> codes this with the struct mdev_parent_ops and provides a single driver
> that shims between the VFIO core and the actual device driver.
> 
> Make every one of the mdev drivers implement an actual struct mdev_driver
> and directly call vfio_register_group_dev() in the probe() function for
> the mdev.
> 
> Squash what is left of the mdev_parent_ops into the mdev_driver and remap
> create(), remove() and mdev_attr_groups to their driver core
> equivalents. Arrange to bind the created mdev_device to the mdev_driver
> that is provided by the end driver.
> 
> The actual execution flow doesn't change much, eg what was
> parent_ops->create is now device_driver->probe and it is called at almost
> the exact same time - except under the normal control of the driver core.
> 
> This allows deleting the entire mdev_drvdata, and tidying some of the
> sysfs. Many places in the drivers start using container_of()
> 
> This cleanly splits the mdev sysfs GUID lifecycle management stuff from
> the vfio_device implementation part, the only VFIO special part of mdev
> that remains is the mdev specific iommu intervention.
> 
> v2:
>  - Keep && m in samples kconfig
>  - Restore accidently squashed removeal of vfio_mdev.c
>  - Remove indirections to call bus_register()/bus_unregister()
>  - Reflow long doc lines
> v1: https://lore.kernel.org/r/0-v1-d88406ed308e+418-vfio3_jgg@nvidia.com
> 
> Jason
> 
> Cc: Leon Romanovsky <leonro@nvidia.com>
> Cc: "Raj, Ashok" <ashok.raj@intel.com>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Max Gurtovoy <mgurtovoy@nvidia.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Tarun Gupta <targupta@nvidia.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> 
> 
> Jason Gunthorpe (13):
>   vfio/mdev: Remove CONFIG_VFIO_MDEV_DEVICE
>   vfio/mdev: Allow the mdev_parent_ops to specify the device driver to
>     bind
>   vfio/mtty: Convert to use vfio_register_group_dev()
>   vfio/mdpy: Convert to use vfio_register_group_dev()
>   vfio/mbochs: Convert to use vfio_register_group_dev()
>   vfio/ap_ops: Convert to use vfio_register_group_dev()
>   vfio/ccw: Convert to use vfio_register_group_dev()
>   vfio/gvt: Convert to use vfio_register_group_dev()
>   vfio/mdev: Remove vfio_mdev.c
>   vfio/mdev: Remove mdev_parent_ops dev_attr_groups
>   vfio/mdev: Remove mdev_parent_ops
>   vfio/mdev: Use the driver core to create the 'remove' file
>   vfio/mdev: Remove mdev drvdata

It'd be really helpful if you could consistently copy at least one
list, preferably one monitored by patchwork, for an entire series.  The
kvm list is missing patches 06 and 08.  I can find the latter hopping
over to the intel-gfx or dri-devel projects as I did for the last
series, but 06 only copied linux-s390, where I need to use lore and
can't find a patchwork.  Thanks,

Alex

> 
>  .../driver-api/vfio-mediated-device.rst       |  56 ++---
>  Documentation/s390/vfio-ap.rst                |   1 -
>  arch/s390/Kconfig                             |   2 +-
>  drivers/gpu/drm/i915/Kconfig                  |   2 +-
>  drivers/gpu/drm/i915/gvt/kvmgt.c              | 210 +++++++++--------
>  drivers/s390/cio/vfio_ccw_drv.c               |  21 +-
>  drivers/s390/cio/vfio_ccw_ops.c               | 136 ++++++-----
>  drivers/s390/cio/vfio_ccw_private.h           |   5 +
>  drivers/s390/crypto/vfio_ap_ops.c             | 138 ++++++-----
>  drivers/s390/crypto/vfio_ap_private.h         |   2 +
>  drivers/vfio/mdev/Kconfig                     |   7 -
>  drivers/vfio/mdev/Makefile                    |   1 -
>  drivers/vfio/mdev/mdev_core.c                 |  67 ++++--
>  drivers/vfio/mdev/mdev_driver.c               |  20 +-
>  drivers/vfio/mdev/mdev_private.h              |   4 +-
>  drivers/vfio/mdev/mdev_sysfs.c                |  37 ++-
>  drivers/vfio/mdev/vfio_mdev.c                 | 180 ---------------
>  drivers/vfio/vfio.c                           |   6 +-
>  include/linux/mdev.h                          |  86 +------
>  include/linux/vfio.h                          |   4 +
>  samples/Kconfig                               |   6 +-
>  samples/vfio-mdev/mbochs.c                    | 166 +++++++------
>  samples/vfio-mdev/mdpy.c                      | 162 +++++++------
>  samples/vfio-mdev/mtty.c                      | 218 +++++++-----------
>  24 files changed, 651 insertions(+), 886 deletions(-)
>  delete mode 100644 drivers/vfio/mdev/vfio_mdev.c
> 

Re: [PATCH v2 00/13] Remove vfio_mdev.c, mdev_parent_ops and more

[Jason Gunthorpe]

On Tue, Apr 27, 2021 at 03:30:42PM -0600, Alex Williamson wrote:
 
> It'd be really helpful if you could consistently copy at least one
> list, preferably one monitored by patchwork, for an entire series.  The
> kvm list is missing patches 06 and 08.  I can find the latter hopping
> over to the intel-gfx or dri-devel projects as I did for the last
> series, but 06 only copied linux-s390, where I need to use lore and
> can't find a patchwork.  Thanks,

Oh wow, that is not intentional, sorry! Thanks for pointing it out

I didn't notice this was happening, basically a side effect of having
so many different people and lists to get on this series - kvm should
have been CC on them all, I fixed it up going forward.

FWIW you may be interested in b4 if you haven't seen it before, it is
a good alternative if there isn't an offical patchworks.

Jason

Re: [PATCH v2 00/13] Remove vfio_mdev.c, mdev_parent_ops and more

[Alex Williamson]

On Tue, 27 Apr 2021 19:20:26 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> On Tue, Apr 27, 2021 at 03:30:42PM -0600, Alex Williamson wrote:
>  
> > It'd be really helpful if you could consistently copy at least one
> > list, preferably one monitored by patchwork, for an entire series.  The
> > kvm list is missing patches 06 and 08.  I can find the latter hopping
> > over to the intel-gfx or dri-devel projects as I did for the last
> > series, but 06 only copied linux-s390, where I need to use lore and
> > can't find a patchwork.  Thanks,  
> 
> Oh wow, that is not intentional, sorry! Thanks for pointing it out
> 
> I didn't notice this was happening, basically a side effect of having
> so many different people and lists to get on this series - kvm should
> have been CC on them all, I fixed it up going forward.
> 
> FWIW you may be interested in b4 if you haven't seen it before, it is
> a good alternative if there isn't an offical patchworks.

I'm sold!  Thanks,

Alex

Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

[Christoph Hellwig]

On Mon, Apr 26, 2021 at 05:00:11PM -0300, Jason Gunthorpe wrote:
> Preserve VFIO's design of allowing mdev drivers to be !GPL by allowing the
> three functions that replace this module for !GPL usage. This goes along
> with the other 19 symbols that are already marked !GPL in VFIO.

NAK.  This was a sneak by Nvidia to try a GPL condom, and now that we
remove that not working condom it does not mean core symbols can be
just changed.

Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

[Greg Kroah-Hartman]

On Wed, Apr 28, 2021 at 08:07:03AM +0200, Christoph Hellwig wrote:
> On Mon, Apr 26, 2021 at 05:00:11PM -0300, Jason Gunthorpe wrote:
> > Preserve VFIO's design of allowing mdev drivers to be !GPL by allowing the
> > three functions that replace this module for !GPL usage. This goes along
> > with the other 19 symbols that are already marked !GPL in VFIO.
> 
> NAK.  This was a sneak by Nvidia to try a GPL condom, and now that we
> remove that not working condom it does not mean core symbols can be
> just changed.

Agreed, these symbols should not be changed.

thanks,

greg k-h

Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

[Jason Gunthorpe]

On Wed, Apr 28, 2021 at 08:36:06AM +0200, Greg Kroah-Hartman wrote:
> On Wed, Apr 28, 2021 at 08:07:03AM +0200, Christoph Hellwig wrote:
> > On Mon, Apr 26, 2021 at 05:00:11PM -0300, Jason Gunthorpe wrote:
> > > Preserve VFIO's design of allowing mdev drivers to be !GPL by allowing the
> > > three functions that replace this module for !GPL usage. This goes along
> > > with the other 19 symbols that are already marked !GPL in VFIO.
> > 
> > NAK.  This was a sneak by Nvidia to try a GPL condom, and now that we
> > remove that not working condom it does not mean core symbols can be
> > just changed.
> 
> Agreed, these symbols should not be changed.

During the development on this series I got a private email that
people have existing !GPL mdev drivers.

When I checked I saw that VFIO community seems to have decided that
!GPL is OK for mdev. I say this because many essential symbols for
implementing a mdev in vfio.c have been marked !GPL:

drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_info_cap_shift);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_info_add_capability);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_set_irqs_validate_and_prepare);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_pin_pages);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_unpin_pages);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_group_pin_pages);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_group_unpin_pages);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_dma_rw);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_register_notifier);
drivers/vfio/vfio.c:EXPORT_SYMBOL(vfio_unregister_notifier);

Why it is like this, I do not know. IMHO it is not some "condom" if a
chunk of the core vfio.c code is marked !GPL and is called by mdev
drivers.

The Linux standard is one patch one change. It is inapporiate for me
to backdoor sneak revert the VFIO communities past decisions on
licensing inside some unrelated cleanup patch.

If you two want to argue VFIO has err'd and should be using GPL for
its API toward mdev then please send a patch to switch the above
symbols and I'll rebase this series ontop of it.

That way the change can get a proper airing and not be sneakily buried
inside a cleanup patch.

Otherwise this patch changes nothing - what existed today continues to
exist, and nothing new is being allowed.

Jason

Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

[Christoph Hellwig]

On Wed, Apr 28, 2021 at 09:53:21AM -0300, Jason Gunthorpe wrote:
> The Linux standard is one patch one change. It is inapporiate for me
> to backdoor sneak revert the VFIO communities past decisions on
> licensing inside some unrelated cleanup patch.

That's not what you are doing.  You are removing weird condom code
that could never work, and remove the sneak attempt of an nvidia employee
to create a derived work that has no legal standing.

> Otherwise this patch changes nothing - what existed today continues to
> exist, and nothing new is being allowed.

No, it changes the existing exports, which is a complete no-go.

Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

[Greg Kroah-Hartman]

On Thu, Apr 29, 2021 at 08:53:15AM +0200, Christoph Hellwig wrote:
> On Wed, Apr 28, 2021 at 09:53:21AM -0300, Jason Gunthorpe wrote:
> > The Linux standard is one patch one change. It is inapporiate for me
> > to backdoor sneak revert the VFIO communities past decisions on
> > licensing inside some unrelated cleanup patch.
> 
> That's not what you are doing.  You are removing weird condom code
> that could never work, and remove the sneak attempt of an nvidia employee
> to create a derived work that has no legal standing.
> 
> > Otherwise this patch changes nothing - what existed today continues to
> > exist, and nothing new is being allowed.
> 
> No, it changes the existing exports, which is a complete no-go.

Agreed, Jason, please do not change the existing exports.

thanks,

greg k-h

Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

[Jason Gunthorpe]

On Thu, Apr 29, 2021 at 08:56:31AM +0200, Greg Kroah-Hartman wrote:
> On Thu, Apr 29, 2021 at 08:53:15AM +0200, Christoph Hellwig wrote:
> > On Wed, Apr 28, 2021 at 09:53:21AM -0300, Jason Gunthorpe wrote:
> > > The Linux standard is one patch one change. It is inapporiate for me
> > > to backdoor sneak revert the VFIO communities past decisions on
> > > licensing inside some unrelated cleanup patch.
> > 
> > That's not what you are doing.  You are removing weird condom code
> > that could never work, and remove the sneak attempt of an nvidia employee
> > to create a derived work that has no legal standing.
> > 
> > > Otherwise this patch changes nothing - what existed today continues to
> > > exist, and nothing new is being allowed.
> > 
> > No, it changes the existing exports, which is a complete no-go.
> 
> Agreed, Jason, please do not change the existing exports.

I respect both of your positions on this topic, but.. I can't be part
of a licensing discussion here.

This is a cleanup project from the Mellanox BU at NVIDIA to get VFIO
more in line with kernel design patterns. Mellanox is fully open
source for all our kernel work and has no stake in these licensing
topics.

As Christoph notes, it seems some other BU at NVIDIA has an interest
here. I hope you'll both understand that I can't get involved in a
licensing topic between the community and some other BU at NVIDIA.

Since none of the past discussions on EXPORT_SYMBOL resulted in any
concrete guidelines to follow, I feel the basic "don't change things"
(in the pragmatic, it worked before, so don't break it sense)
guideline should be applied here.

Since that is not agreeable I will shrink this patch series to remove
the ccw conversion that already has complex feedback and drop this
patch. I'll sadly shelve the rest of the work until something changes.

This will at least allow the coming Intel IDXD mdev driver to be
implemented more cleanly from the start.

Regards,
Jason

Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

[Christoph Hellwig]

On Mon, May 03, 2021 at 02:32:20PM -0300, Jason Gunthorpe wrote:
> Since that is not agreeable I will shrink this patch series to remove
> the ccw conversion that already has complex feedback and drop this
> patch. I'll sadly shelve the rest of the work until something changes.

Please don't.  I'll happily takes on that this is the right work, and
should not be damaged by a bad actor (Nvidia corporate that has been
sneaking weird backdoors into Linux for a while) directing someone
that now works for them through an acquisition.

And we realy need to put Nvidia in the watchlist unfortunately as they
have caused so much damage to Linux through all their crazy backdoors.

Re: [PATCH v2 09/13] vfio/mdev: Remove vfio_mdev.c

[Jason Gunthorpe]

On Tue, May 04, 2021 at 11:38:57AM +0200, Christoph Hellwig wrote:
> On Mon, May 03, 2021 at 02:32:20PM -0300, Jason Gunthorpe wrote:
> > Since that is not agreeable I will shrink this patch series to remove
> > the ccw conversion that already has complex feedback and drop this
> > patch. I'll sadly shelve the rest of the work until something changes.
> 
> Please don't.  I'll happily takes on that this is the right work, and
> should not be damaged by a bad actor (Nvidia corporate that has been
> sneaking weird backdoors into Linux for a while) directing someone
> that now works for them through an acquisition.

If everyone can have a solid agreement on licensing for vfio-mdev
modules then it is fine from my perspective. IMHO that needs to be
settled outside this patch series. If it has to wait while that is
done, then fine.

I'm not being "directed" by NVIDIA. My limitation is I can't be
involved in licensing discussions, and frankly after 25 years of this
I'm tired of them anyhow.

This licensing topic in particular never seems to go anywhere. Half
the participants want EXPORT_SYMBOL() abolished and the other half
view it as an existential requirement. The whole thing is toxic to the
community.

> And we realy need to put Nvidia in the watchlist unfortunately as they
> have caused so much damage to Linux through all their crazy backdoors.

Well that seems impractical.

Check the lwn statistics. NVIDIA is fairly regularly the 10th largest
changeset contributor. We have > 100 people in Mellanox writing kernel
patches and we employ several kernel maintainers now. If the
NVIDIA/ARM purchase goes ahead it will be get even bigger.

All these big amalgamations of people seem to have their unique
challenges, and I'm not convinced NVIDIA is significantly more
damaging to the kernel than Intel, the Android world or other places.

So, let's not paint > 100 developers with such a broad brush please.

I prefer the optimistive view: Mellanox's continued open source
success will be inspiring.

Jason