linux.git/drivers/vfio/mdev/mdev_core.c, branch v6.18.21

drivers: core: remove device_link argument from class_compat_[create|remove]_link

2025-01-10T14:42:20+00:00

After 7e722083fcc3 ("i2c: Remove I2C_COMPAT config symbol and related
code") there's no caller left passing a non-null device_link argument.
So remove this argument to simplify the code.

Signed-off-by: Heiner Kallweit 
Link: https://lore.kernel.org/r/db49131d-fd79-4f23-93f2-0ab541a345fa@gmail.com
Signed-off-by: Greg Kroah-Hartman

vfio/mdev: Move the compat_class initialization to module init

2023-06-27T18:05:26+00:00

The pointer to mdev_bus_compat_class is statically defined at the top
of mdev_core, and was originally (commit 7b96953bc640 ("vfio: Mediated
device Core driver") serialized by the parent_list_lock. The blamed
commit removed this mutex, leaving the pointer initialization
unserialized. As a result, the creation of multiple MDEVs in parallel
(such as during boot) can encounter errors during the creation of the
sysfs entries, such as:

  [    8.337509] sysfs: cannot create duplicate filename '/class/mdev_bus'
  [    8.337514] vfio_ccw 0.0.01d8: MDEV: Registered
  [    8.337516] CPU: 13 PID: 946 Comm: driverctl Not tainted 6.4.0-rc7 #20
  [    8.337522] Hardware name: IBM 3906 M05 780 (LPAR)
  [    8.337525] Call Trace:
  [    8.337528]  [<0000000162b0145a>] dump_stack_lvl+0x62/0x80
  [    8.337540]  [<00000001622aeb30>] sysfs_warn_dup+0x78/0x88
  [    8.337549]  [<00000001622aeca6>] sysfs_create_dir_ns+0xe6/0xf8
  [    8.337552]  [<0000000162b04504>] kobject_add_internal+0xf4/0x340
  [    8.337557]  [<0000000162b04d48>] kobject_add+0x78/0xd0
  [    8.337561]  [<0000000162b04e0a>] kobject_create_and_add+0x6a/0xb8
  [    8.337565]  [<00000001627a110e>] class_compat_register+0x5e/0x90
  [    8.337572]  [<000003ff7fd815da>] mdev_register_parent+0x102/0x130 [mdev]
  [    8.337581]  [<000003ff7fdc7f2c>] vfio_ccw_sch_probe+0xe4/0x178 [vfio_ccw]
  [    8.337588]  [<0000000162a7833c>] css_probe+0x44/0x80
  [    8.337599]  [<000000016279f4da>] really_probe+0xd2/0x460
  [    8.337603]  [<000000016279fa08>] driver_probe_device+0x40/0xf0
  [    8.337606]  [<000000016279fb78>] __device_attach_driver+0xc0/0x140
  [    8.337610]  [<000000016279cbe0>] bus_for_each_drv+0x90/0xd8
  [    8.337618]  [<00000001627a00b0>] __device_attach+0x110/0x190
  [    8.337621]  [<000000016279c7c8>] bus_rescan_devices_helper+0x60/0xb0
  [    8.337626]  [<000000016279cd48>] drivers_probe_store+0x48/0x80
  [    8.337632]  [<00000001622ac9b0>] kernfs_fop_write_iter+0x138/0x1f0
  [    8.337635]  [<00000001621e5e14>] vfs_write+0x1ac/0x2f8
  [    8.337645]  [<00000001621e61d8>] ksys_write+0x70/0x100
  [    8.337650]  [<0000000162b2bdc4>] __do_syscall+0x1d4/0x200
  [    8.337656]  [<0000000162b3c828>] system_call+0x70/0x98
  [    8.337664] kobject: kobject_add_internal failed for mdev_bus with -EEXIST, don't try to register things with the same name in the same directory.
  [    8.337668] kobject: kobject_create_and_add: kobject_add error: -17
  [    8.337674] vfio_ccw: probe of 0.0.01d9 failed with error -12
  [    8.342941] vfio_ccw_mdev aeb9ca91-10c6-42bc-a168-320023570aea: Adding to iommu group 2

Move the initialization of the mdev_bus_compat_class pointer to the
init path, to match the cleanup in module exit. This way the code
in mdev_register_parent() can simply link the new parent to it,
rather than determining whether initialization is required first.

Fixes: 89345d5177aa ("vfio/mdev: embedd struct mdev_parent in the parent data structure")
Reported-by: Alexander Egorenkov 
Signed-off-by: Eric Farman 
Reviewed-by: Kevin Tian 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Tony Krowiak 
Reviewed-by: Jason Gunthorpe 
Link: https://lore.kernel.org/r/20230626133642.2939168-1-farman@linux.ibm.com
Signed-off-by: Alex Williamson

vfio/mdev: add mdev available instance checking to the core

2022-10-04T18:06:58+00:00

Many of the mdev drivers use a simple counter for keeping track of the
available instances. Move this code to the core code and store the counter
in the mdev_parent. Implement it using correct locking, fixing mdpy.

Drivers just provide the value in the mdev_driver at registration time
and the core code takes care of maintaining it and exposing the value in
sysfs.

[hch: count instances per-parent instead of per-type, use an atomic_t
 to avoid taking mdev_list_lock in the show method]

Signed-off-by: Jason Gunthorpe 
Signed-off-by: Christoph Hellwig 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-15-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: remove mtype_get_parent_dev

2022-10-04T18:06:58+00:00

Just open code the dereferences in the only user.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Jason J. Herne 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-10-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: remove mdev_parent_dev

2022-10-04T18:06:58+00:00

Just open code the dereferences in the only user.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Link: https://lore.kernel.org/r/20220923092652.100656-9-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: remove mdev_from_dev

2022-10-04T18:06:58+00:00

Just open code it in the only caller.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Link: https://lore.kernel.org/r/20220923092652.100656-7-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: simplify mdev_type handling

2022-10-04T18:06:58+00:00

Instead of abusing struct attribute_group to control initialization of
struct mdev_type, just define the actual attributes in the mdev_driver,
allocate the mdev_type structures in the caller and pass them to
mdev_register_parent.

This allows the caller to use container_of to get at the containing
structure and thus significantly simplify the code.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Tony Krowiak 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-6-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: embedd struct mdev_parent in the parent data structure

2022-10-04T18:06:58+00:00

Simplify mdev_{un}register_device by requiring the caller to pass in
a structure allocate as part of the parent device structure.  This
removes the need for a list of parents and the separate mdev_parent
refcount as we can simplify rely on the reference to the parent device.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Tony Krowiak 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-5-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: make mdev.h standalone includable

2022-10-04T18:06:58+00:00

Include  and  so that users of this headers
don't need to do that and remove those includes that aren't needed
any more.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Eric Farman 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Tony Krowiak 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Link: https://lore.kernel.org/r/20220923092652.100656-4-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: Use the driver core to create the 'remove' file

2022-04-21T11:36:56+00:00

The device creator is supposed to use the dev.groups value to add sysfs
files before device_add is called, not call sysfs_create_files() after
device_add() returns. This creates a race with uevent delivery where the
extra attribute will not be visible.

This was being done because the groups had been co-opted by the mdev
driver, now that prior patches have moved the driver's groups to the
struct device_driver the dev.group is properly free for use here.

Signed-off-by: Jason Gunthorpe 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Zhi Wang 
Link: http://patchwork.freedesktop.org/patch/msgid/20220411141403.86980-34-hch@lst.de
Reviewed-by: Kirti Wankhede 
Reviewed-by: Zhi Wang