linux-stable.git/drivers/vfio/mdev, branch v5.13.2

vfio/mdev: Correct the function signatures for the mdev_type_attributes

2021-04-12T16:36:00+00:00

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 
Reviewed-by: Cornelia Huck 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jason Gunthorpe 
Message-Id: <18-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson

vfio/mdev: Remove kobj from mdev_parent_ops->create()

2021-04-12T16:36:00+00:00

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 
Reviewed-by: Cornelia Huck 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Jason Gunthorpe 
Message-Id: <17-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson

vfio/mdev: Add mdev/mtype_get_type_group_id()

2021-04-07T21:39:18+00:00

This returns the index in the supported_type_groups array that is
associated with the mdev_type attached to the struct mdev_device or its
containing struct kobject.

Each mdev_device can be spawned from exactly one mdev_type, which in turn
originates from exactly one supported_type_group.

Drivers are using weird string calculations to try and get back to this
index, providing a direct access to the index removes a bunch of wonky
driver code.

mdev_type->group can be deleted as the group is obtained using the
type_group_id.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Kevin Tian 
Reviewed-by: Cornelia Huck 
Signed-off-by: Jason Gunthorpe 
Message-Id: <11-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson

vfio/mdev: Remove duplicate storage of parent in mdev_device

2021-04-07T21:39:18+00:00

mdev_device->type->parent is the same thing.

The struct mdev_device was relying on the kref on the mdev_parent to also
indirectly hold a kref on the mdev_type pointer. Now that the type holds a
kref on the parent we can directly kref the mdev_type and remove this
implicit relationship.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Cornelia Huck 
Signed-off-by: Jason Gunthorpe 
Message-Id: <10-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson

vfio/mdev: Add missing error handling to dev_set_name()

2021-04-07T21:39:18+00:00

This can fail, and seems to be a popular target for syzkaller error
injection. Check the error return and unwind with put_device().

Fixes: 7b96953bc640 ("vfio: Mediated device Core driver")
Reviewed-by: Christoph Hellwig 
Reviewed-by: Kevin Tian 
Reviewed-by: Max Gurtovoy 
Reviewed-by: Cornelia Huck 
Signed-off-by: Jason Gunthorpe 
Message-Id: <9-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson

vfio/mdev: Reorganize mdev_device_create()

2021-04-07T21:39:18+00:00

Once the memory for the struct mdev_device is allocated it should
immediately be device_initialize()'d and filled in so that put_device()
can always be used to undo the allocation.

Place the mdev_get/put_parent() so that they are clearly protecting the
mdev->parent pointer. Move the final put to the release function so that
the lifetime rules are trivial to understand. Update the goto labels to
follow the normal convention.

Remove mdev_device_free() as the release function via device_put() is now
usable in all cases.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Kevin Tian 
Reviewed-by: Cornelia Huck 
Signed-off-by: Jason Gunthorpe 
Message-Id: <8-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson

vfio/mdev: Add missing reference counting to mdev_type

2021-04-07T21:39:17+00:00

struct mdev_type holds a pointer to the kref'd object struct mdev_parent,
but doesn't hold the kref. The lifetime of the parent becomes implicit
because parent_remove_sysfs_files() is supposed to remove all the access
before the parent can be freed, but this is very hard to reason about.

Make it obviously correct by adding the missing get.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Kevin Tian 
Reviewed-by: Cornelia Huck 
Signed-off-by: Jason Gunthorpe 
Message-Id: <7-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson

vfio/mdev: Expose mdev_get/put_parent to mdev_private.h

2021-04-07T21:39:17+00:00

The next patch will use these in mdev_sysfs.c

While here remove the now dead code checks for NULL, a mdev_type can never
have a NULL parent.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Kevin Tian 
Reviewed-by: Cornelia Huck 
Signed-off-by: Jason Gunthorpe 
Message-Id: <6-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson

vfio/mdev: Use struct mdev_type in struct mdev_device

2021-04-07T21:39:17+00:00

The kobj pointer in mdev_device is actually pointing at a struct
mdev_type. Use the proper type so things are understandable.

There are a number of places that are confused and passing both the mdev
and the mtype as function arguments, fix these to derive the mtype
directly from the mdev to remove the redundancy.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Kevin Tian 
Reviewed-by: Cornelia Huck 
Signed-off-by: Jason Gunthorpe 
Message-Id: <5-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson

vfio/mdev: Simplify driver registration

2021-04-07T21:39:16+00:00

This is only done once, we don't need to generate code to initialize a
structure stored in the ELF .data segment. Fill in the three required
.driver members directly instead of copying data into them during
mdev_register_driver().

Further the to_mdev_driver() function doesn't belong in a public header,
just inline it into the two places that need it. Finally, we can now
clearly see that 'drv' derived from dev->driver cannot be NULL, firstly
because the driver core forbids it, and secondly because NULL won't pass
through the container_of(). Remove the dead code.

Reviewed-by: Christoph Hellwig 
Reviewed-by: Kevin Tian 
Reviewed-by: Cornelia Huck 
Signed-off-by: Jason Gunthorpe 
Message-Id: <4-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com>
Signed-off-by: Alex Williamson