[PATCH v2 00/18] Make vfio_mdev type safe

[PATCH v2 00/18] Make vfio_mdev type safe

[Jason Gunthorpe]

vfio_mdev has a number of different objects: mdev_parent, mdev_type and
mdev_device.

Unfortunately the types of these have been erased in various places
throughout the API, and this makes it very hard to understand this code or
maintain it by the time it reaches all of the drivers.

This series puts in all the types and aligns some of the design with the
driver core standard for a driver core bus driver:

 - Replace 'struct device *' with 'struct mdev_device *
 - Replace 'struct device *' with 'struct mdev_type *' and
   mtype_get_parent_dev()
 - Replace 'struct kobject *' with 'struct mdev_type *'

Now that types are clear it is easy to spot a few places that have
duplicated information.

More significantly we can now understand how to directly fix the
obfuscated 'kobj->name' matching by realizing the the kobj is a mdev_type,
which is linked to the supported_types_list provided by the driver, and
thus the core code can directly return the array indexes all the drivers
actually want.

v2:
 - Use a mdev_type local in mdev_create_sysfs_files
 - Rename the goto unwind labels in mdev_device_free()
 - Reorder patches, annotate reviewed-by's thanks all
v1: https://lore.kernel.org/r/0-v1-7dedf20b2b75+4f785-vfio2_jgg@nvidia.com

Jason Gunthorpe (18):
  vfio/mdev: Fix missing static's on MDEV_TYPE_ATTR's
  vfio/mdev: Do not allow a mdev_type to have a NULL parent pointer
  vfio/mdev: Add missing typesafety around mdev_device
  vfio/mdev: Simplify driver registration
  vfio/mdev: Use struct mdev_type in struct mdev_device
  vfio/mdev: Expose mdev_get/put_parent to mdev_private.h
  vfio/mdev: Add missing reference counting to mdev_type
  vfio/mdev: Reorganize mdev_device_create()
  vfio/mdev: Add missing error handling to dev_set_name()
  vfio/mdev: Remove duplicate storage of parent in mdev_device
  vfio/mdev: Add mdev/mtype_get_type_group_id()
  vfio/mtty: Use mdev_get_type_group_id()
  vfio/mdpy: Use mdev_get_type_group_id()
  vfio/mbochs: Use mdev_get_type_group_id()
  vfio/gvt: Make DRM_I915_GVT depend on VFIO_MDEV
  vfio/gvt: Use mdev_get_type_group_id()
  vfio/mdev: Remove kobj from mdev_parent_ops->create()
  vfio/mdev: Correct the function signatures for the
    mdev_type_attributes

 .../driver-api/vfio-mediated-device.rst       |   9 +-
 drivers/gpu/drm/i915/Kconfig                  |   1 +
 drivers/gpu/drm/i915/gvt/gvt.c                |  41 ++---
 drivers/gpu/drm/i915/gvt/gvt.h                |   4 +-
 drivers/gpu/drm/i915/gvt/kvmgt.c              |   7 +-
 drivers/s390/cio/vfio_ccw_ops.c               |  17 +-
 drivers/s390/crypto/vfio_ap_ops.c             |  14 +-
 drivers/vfio/mdev/mdev_core.c                 | 174 +++++++-----------
 drivers/vfio/mdev/mdev_driver.c               |  19 +-
 drivers/vfio/mdev/mdev_private.h              |  40 ++--
 drivers/vfio/mdev/mdev_sysfs.c                |  59 +++---
 drivers/vfio/mdev/vfio_mdev.c                 |  29 +--
 drivers/vfio/vfio_iommu_type1.c               |  25 +--
 include/linux/mdev.h                          |  80 +++++---
 samples/vfio-mdev/mbochs.c                    |  55 +++---
 samples/vfio-mdev/mdpy.c                      |  56 +++---
 samples/vfio-mdev/mtty.c                      |  66 ++-----
 17 files changed, 313 insertions(+), 383 deletions(-)

-- 
2.31.1

[PATCH v2 17/18] vfio/mdev: Remove kobj from mdev_parent_ops->create()

[Jason Gunthorpe]

The kobj here is a type-erased version of mdev_type, which is already
stored in the struct mdev_device being passed in. It was only ever used to
compute the type_group_id, which is now extracted directly from the mdev.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/gpu/drm/i915/gvt/kvmgt.c  | 2 +-
 drivers/s390/cio/vfio_ccw_ops.c   | 2 +-
 drivers/s390/crypto/vfio_ap_ops.c | 2 +-
 drivers/vfio/mdev/mdev_core.c     | 2 +-
 include/linux/mdev.h              | 3 +--
 samples/vfio-mdev/mbochs.c        | 2 +-
 samples/vfio-mdev/mdpy.c          | 2 +-
 samples/vfio-mdev/mtty.c          | 2 +-
 8 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 16e1e4a38aa1f6..6bf176e8426e63 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -689,7 +689,7 @@ static void kvmgt_put_vfio_device(void *vgpu)
 	vfio_device_put(vdev->vfio_device);
 }
 
-static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
+static int intel_vgpu_create(struct mdev_device *mdev)
 {
 	struct intel_vgpu *vgpu = NULL;
 	struct intel_vgpu_type *type;
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 767ac41686fe2f..10407cf67583c6 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -110,7 +110,7 @@ static struct attribute_group *mdev_type_groups[] = {
 	NULL,
 };
 
-static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
+static int vfio_ccw_mdev_create(struct mdev_device *mdev)
 {
 	struct vfio_ccw_private *private =
 		dev_get_drvdata(mdev_parent_dev(mdev));
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 1ffdd411201cd6..d319152dd484a2 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -322,7 +322,7 @@ static void vfio_ap_matrix_init(struct ap_config_info *info,
 	matrix->adm_max = info->apxa ? info->Nd : 15;
 }
 
-static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
+static int vfio_ap_mdev_create(struct mdev_device *mdev)
 {
 	struct ap_matrix_mdev *matrix_mdev;
 
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 5ae06f951a0998..10eff33ce1f263 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -286,7 +286,7 @@ int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
 		goto out_put_device;
 	}
 
-	ret = parent->ops->create(&type->kobj, mdev);
+	ret = parent->ops->create(mdev);
 	if (ret)
 		goto out_unlock;
 
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index 41e91936522394..c3a800051d6146 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -61,7 +61,6 @@ unsigned int mtype_get_type_group_id(struct kobject *mtype_kobj);
  * @create:		Called to allocate basic resources in parent device's
  *			driver for a particular mediated device. It is
  *			mandatory to provide create ops.
- *			@kobj: kobject of type for which 'create' is called.
  *			@mdev: mdev_device structure on of mediated device
  *			      that is being created
  *			Returns integer: success (0) or error (< 0)
@@ -107,7 +106,7 @@ struct mdev_parent_ops {
 	const struct attribute_group **mdev_attr_groups;
 	struct attribute_group **supported_type_groups;
 
-	int     (*create)(struct kobject *kobj, struct mdev_device *mdev);
+	int     (*create)(struct mdev_device *mdev);
 	int     (*remove)(struct mdev_device *mdev);
 	int     (*open)(struct mdev_device *mdev);
 	void    (*release)(struct mdev_device *mdev);
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index a1af30df10a2ee..ac4d0dc2490705 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -506,7 +506,7 @@ static int mbochs_reset(struct mdev_device *mdev)
 	return 0;
 }
 
-static int mbochs_create(struct kobject *kobj, struct mdev_device *mdev)
+static int mbochs_create(struct mdev_device *mdev)
 {
 	const struct mbochs_type *type =
 		&mbochs_types[mdev_get_type_group_id(mdev)];
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index 08c15f9f06a880..da88fd7dd42329 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -216,7 +216,7 @@ static int mdpy_reset(struct mdev_device *mdev)
 	return 0;
 }
 
-static int mdpy_create(struct kobject *kobj, struct mdev_device *mdev)
+static int mdpy_create(struct mdev_device *mdev)
 {
 	const struct mdpy_type *type =
 		&mdpy_types[mdev_get_type_group_id(mdev)];
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index 191a587a8d5ab1..f2e36c06ac6aa2 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -708,7 +708,7 @@ static ssize_t mdev_access(struct mdev_device *mdev, u8 *buf, size_t count,
 	return ret;
 }
 
-static int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
+static int mtty_create(struct mdev_device *mdev)
 {
 	struct mdev_state *mdev_state;
 	int nr_ports = mdev_get_type_group_id(mdev) + 1;
-- 
2.31.1

[PATCH v2 18/18] vfio/mdev: Correct the function signatures for the mdev_type_attributes

[Jason Gunthorpe]

The driver core standard is to pass in the properly typed object, the
properly typed attribute and the buffer data. It stems from the root
kobject method:

  ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *attr,..)

Each subclass of kobject should provide their own function with the same
signature but more specific types, eg struct device uses:

  ssize_t (*show)(struct device *dev, struct device_attribute *attr,..)

In this case the existing signature is:

  ssize_t (*show)(struct kobject *kobj, struct device *dev,..)

Where kobj is a 'struct mdev_type *' and dev is 'mdev_type->parent->dev'.

Change the mdev_type related sysfs attribute functions to:

  ssize_t (*show)(struct mdev_type *mtype, struct mdev_type_attribute *attr,..)

In order to restore type safety and match the driver core standard

There are no current users of 'attr', but if it is ever needed it would be
hard to add in retroactively, so do it now.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/gpu/drm/i915/gvt/gvt.c    | 21 +++++++++++----------
 drivers/s390/cio/vfio_ccw_ops.c   | 15 +++++++++------
 drivers/s390/crypto/vfio_ap_ops.c | 12 +++++++-----
 drivers/vfio/mdev/mdev_core.c     | 14 ++++++++++++--
 drivers/vfio/mdev/mdev_sysfs.c    | 11 ++++++-----
 include/linux/mdev.h              | 11 +++++++----
 samples/vfio-mdev/mbochs.c        | 26 +++++++++++++++-----------
 samples/vfio-mdev/mdpy.c          | 24 ++++++++++++++----------
 samples/vfio-mdev/mtty.c          | 18 +++++++++---------
 9 files changed, 90 insertions(+), 62 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/gvt.c b/drivers/gpu/drm/i915/gvt/gvt.c
index 4b47a18e9dfa0f..3703814a669b46 100644
--- a/drivers/gpu/drm/i915/gvt/gvt.c
+++ b/drivers/gpu/drm/i915/gvt/gvt.c
@@ -54,14 +54,15 @@ intel_gvt_find_vgpu_type(struct intel_gvt *gvt, unsigned int type_group_id)
 	return &gvt->types[type_group_id];
 }
 
-static ssize_t available_instances_show(struct kobject *kobj,
-					struct device *dev, char *buf)
+static ssize_t available_instances_show(struct mdev_type *mtype,
+					struct mdev_type_attribute *attr,
+					char *buf)
 {
 	struct intel_vgpu_type *type;
 	unsigned int num = 0;
-	void *gvt = kdev_to_i915(dev)->gvt;
+	void *gvt = kdev_to_i915(mtype_get_parent_dev(mtype))->gvt;
 
-	type = intel_gvt_find_vgpu_type(gvt, mtype_get_type_group_id(kobj));
+	type = intel_gvt_find_vgpu_type(gvt, mtype_get_type_group_id(mtype));
 	if (!type)
 		num = 0;
 	else
@@ -70,19 +71,19 @@ static ssize_t available_instances_show(struct kobject *kobj,
 	return sprintf(buf, "%u\n", num);
 }
 
-static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
-		char *buf)
+static ssize_t device_api_show(struct mdev_type *mtype,
+			       struct mdev_type_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
 }
 
-static ssize_t description_show(struct kobject *kobj, struct device *dev,
-		char *buf)
+static ssize_t description_show(struct mdev_type *mtype,
+				struct mdev_type_attribute *attr, char *buf)
 {
 	struct intel_vgpu_type *type;
-	void *gvt = kdev_to_i915(dev)->gvt;
+	void *gvt = kdev_to_i915(mtype_get_parent_dev(mtype))->gvt;
 
-	type = intel_gvt_find_vgpu_type(gvt, mtype_get_type_group_id(kobj));
+	type = intel_gvt_find_vgpu_type(gvt, mtype_get_type_group_id(mtype));
 	if (!type)
 		return 0;
 
diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index 10407cf67583c6..491a64c61fff1a 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -71,23 +71,26 @@ static int vfio_ccw_mdev_notifier(struct notifier_block *nb,
 	return NOTIFY_DONE;
 }
 
-static ssize_t name_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t name_show(struct mdev_type *mtype,
+			 struct mdev_type_attribute *attr, char *buf)
 {
 	return sprintf(buf, "I/O subchannel (Non-QDIO)\n");
 }
 static MDEV_TYPE_ATTR_RO(name);
 
-static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
-			       char *buf)
+static ssize_t device_api_show(struct mdev_type *mtype,
+			       struct mdev_type_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%s\n", VFIO_DEVICE_API_CCW_STRING);
 }
 static MDEV_TYPE_ATTR_RO(device_api);
 
-static ssize_t available_instances_show(struct kobject *kobj,
-					struct device *dev, char *buf)
+static ssize_t available_instances_show(struct mdev_type *mtype,
+					struct mdev_type_attribute *attr,
+					char *buf)
 {
-	struct vfio_ccw_private *private = dev_get_drvdata(dev);
+	struct vfio_ccw_private *private =
+		dev_get_drvdata(mtype_get_parent_dev(mtype));
 
 	return sprintf(buf, "%d\n", atomic_read(&private->avail));
 }
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index d319152dd484a2..0ce00c9311d378 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -366,15 +366,17 @@ static int vfio_ap_mdev_remove(struct mdev_device *mdev)
 	return 0;
 }
 
-static ssize_t name_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t name_show(struct mdev_type *mtype,
+			 struct mdev_type_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%s\n", VFIO_AP_MDEV_NAME_HWVIRT);
 }
 
 static MDEV_TYPE_ATTR_RO(name);
 
-static ssize_t available_instances_show(struct kobject *kobj,
-					struct device *dev, char *buf)
+static ssize_t available_instances_show(struct mdev_type *mtype,
+					struct mdev_type_attribute *attr,
+					char *buf)
 {
 	return sprintf(buf, "%d\n",
 		       atomic_read(&matrix_dev->available_instances));
@@ -382,8 +384,8 @@ static ssize_t available_instances_show(struct kobject *kobj,
 
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
-			       char *buf)
+static ssize_t device_api_show(struct mdev_type *mtype,
+			       struct mdev_type_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%s\n", VFIO_DEVICE_API_AP_STRING);
 }
diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 10eff33ce1f263..2a85d6fcb7ddd0 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -47,12 +47,22 @@ EXPORT_SYMBOL(mdev_get_type_group_id);
  * Used in mdev_type_attribute sysfs functions to return the index in the
  * supported_type_groups that the sysfs is called from.
  */
-unsigned int mtype_get_type_group_id(struct kobject *mtype_kobj)
+unsigned int mtype_get_type_group_id(struct mdev_type *mtype)
 {
-	return container_of(mtype_kobj, struct mdev_type, kobj)->type_group_id;
+	return mtype->type_group_id;
 }
 EXPORT_SYMBOL(mtype_get_type_group_id);
 
+/*
+ * Used in mdev_type_attribute sysfs functions to return the parent struct
+ * device
+ */
+struct device *mtype_get_parent_dev(struct mdev_type *mtype)
+{
+	return mtype->parent->dev;
+}
+EXPORT_SYMBOL(mtype_get_parent_dev);
+
 /* Should be called holding parent_list_lock */
 static struct mdev_parent *__find_parent_device(struct device *dev)
 {
diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
index 712fbc78b12e2d..f5cf1931c54e48 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -26,7 +26,7 @@ static ssize_t mdev_type_attr_show(struct kobject *kobj,
 	ssize_t ret = -EIO;
 
 	if (attr->show)
-		ret = attr->show(kobj, type->parent->dev, buf);
+		ret = attr->show(type, attr, buf);
 	return ret;
 }
 
@@ -39,7 +39,7 @@ static ssize_t mdev_type_attr_store(struct kobject *kobj,
 	ssize_t ret = -EIO;
 
 	if (attr->store)
-		ret = attr->store(&type->kobj, type->parent->dev, buf, count);
+		ret = attr->store(type, attr, buf, count);
 	return ret;
 }
 
@@ -48,8 +48,9 @@ static const struct sysfs_ops mdev_type_sysfs_ops = {
 	.store = mdev_type_attr_store,
 };
 
-static ssize_t create_store(struct kobject *kobj, struct device *dev,
-			    const char *buf, size_t count)
+static ssize_t create_store(struct mdev_type *mtype,
+			    struct mdev_type_attribute *attr, const char *buf,
+			    size_t count)
 {
 	char *str;
 	guid_t uuid;
@@ -67,7 +68,7 @@ static ssize_t create_store(struct kobject *kobj, struct device *dev,
 	if (ret)
 		return ret;
 
-	ret = mdev_device_create(to_mdev_type(kobj), &uuid);
+	ret = mdev_device_create(mtype, &uuid);
 	if (ret)
 		return ret;
 
diff --git a/include/linux/mdev.h b/include/linux/mdev.h
index c3a800051d6146..1fb34ea394ad46 100644
--- a/include/linux/mdev.h
+++ b/include/linux/mdev.h
@@ -47,7 +47,8 @@ static inline struct device *mdev_get_iommu_device(struct mdev_device *mdev)
 }
 
 unsigned int mdev_get_type_group_id(struct mdev_device *mdev);
-unsigned int mtype_get_type_group_id(struct kobject *mtype_kobj);
+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
@@ -123,9 +124,11 @@ struct mdev_parent_ops {
 /* interface for exporting mdev supported type attributes */
 struct mdev_type_attribute {
 	struct attribute attr;
-	ssize_t (*show)(struct kobject *kobj, struct device *dev, char *buf);
-	ssize_t (*store)(struct kobject *kobj, struct device *dev,
-			 const char *buf, size_t count);
+	ssize_t (*show)(struct mdev_type *mtype,
+			struct mdev_type_attribute *attr, char *buf);
+	ssize_t (*store)(struct mdev_type *mtype,
+			 struct mdev_type_attribute *attr, const char *buf,
+			 size_t count);
 };
 
 #define MDEV_TYPE_ATTR(_name, _mode, _show, _store)		\
diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c
index ac4d0dc2490705..861c76914e7639 100644
--- a/samples/vfio-mdev/mbochs.c
+++ b/samples/vfio-mdev/mbochs.c
@@ -1330,37 +1330,41 @@ static const struct attribute_group *mdev_dev_groups[] = {
 	NULL,
 };
 
-static ssize_t
-name_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t name_show(struct mdev_type *mtype,
+			 struct mdev_type_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%s\n", kobj->name);
+	const struct mbochs_type *type =
+		&mbochs_types[mtype_get_type_group_id(mtype)];
+
+	return sprintf(buf, "%s\n", type->name);
 }
 static MDEV_TYPE_ATTR_RO(name);
 
-static ssize_t
-description_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t description_show(struct mdev_type *mtype,
+				struct mdev_type_attribute *attr, char *buf)
 {
 	const struct mbochs_type *type =
-		&mbochs_types[mtype_get_type_group_id(kobj)];
+		&mbochs_types[mtype_get_type_group_id(mtype)];
 
 	return sprintf(buf, "virtual display, %d MB video memory\n",
 		       type ? type->mbytes  : 0);
 }
 static MDEV_TYPE_ATTR_RO(description);
 
-static ssize_t
-available_instances_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t available_instances_show(struct mdev_type *mtype,
+					struct mdev_type_attribute *attr,
+					char *buf)
 {
 	const struct mbochs_type *type =
-		&mbochs_types[mtype_get_type_group_id(kobj)];
+		&mbochs_types[mtype_get_type_group_id(mtype)];
 	int count = (max_mbytes - mbochs_used_mbytes) / type->mbytes;
 
 	return sprintf(buf, "%d\n", count);
 }
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
-			       char *buf)
+static ssize_t device_api_show(struct mdev_type *mtype,
+			       struct mdev_type_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
 }
diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c
index da88fd7dd42329..885b88ea20e234 100644
--- a/samples/vfio-mdev/mdpy.c
+++ b/samples/vfio-mdev/mdpy.c
@@ -652,18 +652,21 @@ static const struct attribute_group *mdev_dev_groups[] = {
 	NULL,
 };
 
-static ssize_t
-name_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t name_show(struct mdev_type *mtype,
+			 struct mdev_type_attribute *attr, char *buf)
 {
-	return sprintf(buf, "%s\n", kobj->name);
+	const struct mdpy_type *type =
+		&mdpy_types[mtype_get_type_group_id(mtype)];
+
+	return sprintf(buf, "%s\n", type->name);
 }
 static MDEV_TYPE_ATTR_RO(name);
 
-static ssize_t
-description_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t description_show(struct mdev_type *mtype,
+				struct mdev_type_attribute *attr, char *buf)
 {
 	const struct mdpy_type *type =
-		&mdpy_types[mtype_get_type_group_id(kobj)];
+		&mdpy_types[mtype_get_type_group_id(mtype)];
 
 	return sprintf(buf, "virtual display, %dx%d framebuffer\n",
 		       type ? type->width  : 0,
@@ -671,15 +674,16 @@ description_show(struct kobject *kobj, struct device *dev, char *buf)
 }
 static MDEV_TYPE_ATTR_RO(description);
 
-static ssize_t
-available_instances_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t available_instances_show(struct mdev_type *mtype,
+					struct mdev_type_attribute *attr,
+					char *buf)
 {
 	return sprintf(buf, "%d\n", max_devices - mdpy_count);
 }
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
-			       char *buf)
+static ssize_t device_api_show(struct mdev_type *mtype,
+			       struct mdev_type_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
 }
diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c
index f2e36c06ac6aa2..b9b24be4abdab7 100644
--- a/samples/vfio-mdev/mtty.c
+++ b/samples/vfio-mdev/mtty.c
@@ -1292,23 +1292,24 @@ static const struct attribute_group *mdev_dev_groups[] = {
 	NULL,
 };
 
-static ssize_t
-name_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t name_show(struct mdev_type *mtype,
+			 struct mdev_type_attribute *attr, char *buf)
 {
 	static const char *name_str[2] = { "Single port serial",
 					   "Dual port serial" };
 
 	return sysfs_emit(buf, "%s\n",
-			  name_str[mtype_get_type_group_id(kobj)]);
+			  name_str[mtype_get_type_group_id(mtype)]);
 }
 
 static MDEV_TYPE_ATTR_RO(name);
 
-static ssize_t
-available_instances_show(struct kobject *kobj, struct device *dev, char *buf)
+static ssize_t available_instances_show(struct mdev_type *mtype,
+					struct mdev_type_attribute *attr,
+					char *buf)
 {
 	struct mdev_state *mds;
-	unsigned int ports = mtype_get_type_group_id(kobj) + 1;
+	unsigned int ports = mtype_get_type_group_id(mtype) + 1;
 	int used = 0;
 
 	list_for_each_entry(mds, &mdev_devices_list, next)
@@ -1319,9 +1320,8 @@ available_instances_show(struct kobject *kobj, struct device *dev, char *buf)
 
 static MDEV_TYPE_ATTR_RO(available_instances);
 
-
-static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
-			       char *buf)
+static ssize_t device_api_show(struct mdev_type *mtype,
+			       struct mdev_type_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%s\n", VFIO_DEVICE_API_PCI_STRING);
 }
-- 
2.31.1

Re: [PATCH v2 00/18] Make vfio_mdev type safe

[Alex Williamson]

On Tue,  6 Apr 2021 16:40:23 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> vfio_mdev has a number of different objects: mdev_parent, mdev_type and
> mdev_device.
> 
> Unfortunately the types of these have been erased in various places
> throughout the API, and this makes it very hard to understand this code or
> maintain it by the time it reaches all of the drivers.
> 
> This series puts in all the types and aligns some of the design with the
> driver core standard for a driver core bus driver:
> 
>  - Replace 'struct device *' with 'struct mdev_device *
>  - Replace 'struct device *' with 'struct mdev_type *' and
>    mtype_get_parent_dev()
>  - Replace 'struct kobject *' with 'struct mdev_type *'
> 
> Now that types are clear it is easy to spot a few places that have
> duplicated information.
> 
> More significantly we can now understand how to directly fix the
> obfuscated 'kobj->name' matching by realizing the the kobj is a mdev_type,
> which is linked to the supported_types_list provided by the driver, and
> thus the core code can directly return the array indexes all the drivers
> actually want.
> 
> v2:
>  - Use a mdev_type local in mdev_create_sysfs_files
>  - Rename the goto unwind labels in mdev_device_free()
>  - Reorder patches, annotate reviewed-by's thanks all
> v1: https://lore.kernel.org/r/0-v1-7dedf20b2b75+4f785-vfio2_jgg@nvidia.com
> 
> Jason Gunthorpe (18):
>   vfio/mdev: Fix missing static's on MDEV_TYPE_ATTR's
>   vfio/mdev: Do not allow a mdev_type to have a NULL parent pointer
>   vfio/mdev: Add missing typesafety around mdev_device
>   vfio/mdev: Simplify driver registration
>   vfio/mdev: Use struct mdev_type in struct mdev_device
>   vfio/mdev: Expose mdev_get/put_parent to mdev_private.h
>   vfio/mdev: Add missing reference counting to mdev_type
>   vfio/mdev: Reorganize mdev_device_create()
>   vfio/mdev: Add missing error handling to dev_set_name()
>   vfio/mdev: Remove duplicate storage of parent in mdev_device
>   vfio/mdev: Add mdev/mtype_get_type_group_id()
>   vfio/mtty: Use mdev_get_type_group_id()
>   vfio/mdpy: Use mdev_get_type_group_id()
>   vfio/mbochs: Use mdev_get_type_group_id()
>   vfio/gvt: Make DRM_I915_GVT depend on VFIO_MDEV
>   vfio/gvt: Use mdev_get_type_group_id()
>   vfio/mdev: Remove kobj from mdev_parent_ops->create()
>   vfio/mdev: Correct the function signatures for the
>     mdev_type_attributes
> 
>  .../driver-api/vfio-mediated-device.rst       |   9 +-
>  drivers/gpu/drm/i915/Kconfig                  |   1 +
>  drivers/gpu/drm/i915/gvt/gvt.c                |  41 ++---
>  drivers/gpu/drm/i915/gvt/gvt.h                |   4 +-
>  drivers/gpu/drm/i915/gvt/kvmgt.c              |   7 +-
>  drivers/s390/cio/vfio_ccw_ops.c               |  17 +-
>  drivers/s390/crypto/vfio_ap_ops.c             |  14 +-
>  drivers/vfio/mdev/mdev_core.c                 | 174 +++++++-----------
>  drivers/vfio/mdev/mdev_driver.c               |  19 +-
>  drivers/vfio/mdev/mdev_private.h              |  40 ++--
>  drivers/vfio/mdev/mdev_sysfs.c                |  59 +++---
>  drivers/vfio/mdev/vfio_mdev.c                 |  29 +--
>  drivers/vfio/vfio_iommu_type1.c               |  25 +--
>  include/linux/mdev.h                          |  80 +++++---
>  samples/vfio-mdev/mbochs.c                    |  55 +++---
>  samples/vfio-mdev/mdpy.c                      |  56 +++---
>  samples/vfio-mdev/mtty.c                      |  66 ++-----
>  17 files changed, 313 insertions(+), 383 deletions(-)

Applied to vfio next branch for v5.13.  Thanks!

Alex