vfio/mdev: Do not allow a mdev_type to have a NULL parent pointer

2021-05-22T08:57:31+00:00

[ Upstream commit b5a1f8921d5040bb788492bf33a66758021e4be5 ] There is a small race where the parent is NULL even though the kobj has already been made visible in sysfs. For instance the attribute_group is made visible in sysfs_create_files() and the mdev_type_attr_show() does: ret = attr->show(kobj, type->parent->dev, buf); Which will crash on NULL parent. Move the parent setup to before the type pointer leaves the stack frame. 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: <2-v2-d36939638fc6+d54-vfio2_jgg@nvidia.com> Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin

vfio/mdev: Fix reference count leak in add_mdev_supported_type

2020-06-25T13:41:56+00:00

[ Upstream commit aa8ba13cae3134b8ef1c1b6879f66372531da738 ] kobject_init_and_add() takes reference even when it fails. If this function returns an error, kobject_put() must be called to properly clean up the memory associated with the object. Thus, replace kfree() by kobject_put() to fix this issue. Previous commit "b8eb718348b8" fixed a similar problem. Fixes: 7b96953bc640 ("vfio: Mediated device Core driver") Signed-off-by: Qiushi Wu Reviewed-by: Cornelia Huck Reviewed-by: Kirti Wankhede Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin

vfio-mdev: de-polute the namespace, rename parent_device & parent_ops

2016-12-30T15:13:38+00:00

Add an mdev_ prefix so we're not poluting the namespace so much. Cc: Zhenyu Wang Cc: Zhi Wang Cc: Jike Song Signed-off-by: Alex Williamson Reviewed by: Kirti Wankhede

vfio: Mediated device Core driver

2016-11-17T15:24:48+00:00

Design for Mediated Device Driver: Main purpose of this driver is to provide a common interface for mediated device management that can be used by different drivers of different devices. This module provides a generic interface to create the device, add it to mediated bus, add device to IOMMU group and then add it to vfio group. Below is the high Level block diagram, with Nvidia, Intel and IBM devices as example, since these are the devices which are going to actively use this module as of now. +---------------+ | | | +-----------+ | mdev_register_driver() +--------------+ | | | +<------------------------+ __init() | | | mdev | | | | | | bus | +------------------------>+ |<-> VFIO user | | driver | | probe()/remove() | vfio_mdev.ko | APIs | | | | | | | +-----------+ | +--------------+ | | | MDEV CORE | | MODULE | | mdev.ko | | +-----------+ | mdev_register_device() +--------------+ | | | +<------------------------+ | | | | | | nvidia.ko |<-> physical | | | +------------------------>+ | device | | | | callback +--------------+ | | Physical | | | | device | | mdev_register_device() +--------------+ | | interface | |<------------------------+ | | | | | | i915.ko |<-> physical | | | +------------------------>+ | device | | | | callback +--------------+ | | | | | | | | mdev_register_device() +--------------+ | | | +<------------------------+ | | | | | | ccw_device.ko|<-> physical | | | +------------------------>+ | device | | | | callback +--------------+ | +-----------+ | +---------------+ Core driver provides two types of registration interfaces: 1. Registration interface for mediated bus driver: /** * struct mdev_driver - Mediated device's driver * @name: driver name * @probe: called when new device created * @remove:called when device removed * @driver:device driver structure * **/ struct mdev_driver { const char *name; int (*probe) (struct device *dev); void (*remove) (struct device *dev); struct device_driver driver; }; Mediated bus driver for mdev device should use this interface to register and unregister with core driver respectively: int mdev_register_driver(struct mdev_driver *drv, struct module *owner); void mdev_unregister_driver(struct mdev_driver *drv); Mediated bus driver is responsible to add/delete mediated devices to/from VFIO group when devices are bound and unbound to the driver. 2. Physical device driver interface This interface provides vendor driver the set APIs to manage physical device related work in its driver. APIs are : * dev_attr_groups: attributes of the parent device. * mdev_attr_groups: attributes of the mediated device. * supported_type_groups: attributes to define supported type. This is mandatory field. * create: to allocate basic resources in vendor driver for a mediated device. This is mandatory to be provided by vendor driver. * remove: to free resources in vendor driver when mediated device is destroyed. This is mandatory to be provided by vendor driver. * open: open callback of mediated device * release: release callback of mediated device * read : read emulation callback. * write: write emulation callback. * ioctl: ioctl callback. * mmap: mmap emulation callback. Drivers should use these interfaces to register and unregister device to mdev core driver respectively: extern int mdev_register_device(struct device *dev, const struct parent_ops *ops); extern void mdev_unregister_device(struct device *dev); There are no locks to serialize above callbacks in mdev driver and vfio_mdev driver. If required, vendor driver can have locks to serialize above APIs in their driver. Signed-off-by: Kirti Wankhede Signed-off-by: Neo Jia Reviewed-by: Jike Song Reviewed-by: Dong Jia Shi Signed-off-by: Alex Williamson

kernel/linux.git/drivers/vfio/mdev/mdev_sysfs.c, branch v4.14.263

vfio/mdev: Do not allow a mdev_type to have a NULL parent pointer

vfio/mdev: Fix reference count leak in add_mdev_supported_type

vfio-mdev: de-polute the namespace, rename parent_device & parent_ops

vfio: Mediated device Core driver