linux-stable.git/drivers/vfio/mdev, branch linux-6.3.y

vfio/mdev: Move the compat_class initialization to module init

2023-07-11T17:39:49+00:00

[ Upstream commit ff598081e5b9d0bdd6874bfe340811bbb75b35e4 ]

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 
Signed-off-by: Sasha Levin

vfio/mdev: Use sysfs_emit() to instead of sprintf()

2023-01-30T19:16:13+00:00

Follow the advice of the Documentation/filesystems/sysfs.rst and show()
should only use sysfs_emit() or sysfs_emit_at() when formatting the
value to be returned to user space.

Signed-off-by: Bo Liu 
Reviewed-by: Jason Gunthorpe 
Link: https://lore.kernel.org/r/20230129084117.2384-1-liubo03@inspur.com
Signed-off-by: Alex Williamson

vfio-mdev: turn VFIO_MDEV into a selectable symbol

2023-01-23T18:26:29+00:00

VFIO_MDEV is just a library with helpers for the drivers.  Stop making
it a user choice and just select it by the drivers that use the helpers.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Tony Krowiak 
Link: https://lore.kernel.org/r/20230110091009.474427-3-hch@lst.de
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: consolidate all the description sysfs into the core code

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

Every driver just emits a string, simply add a method to the mdev_driver
to return it and provide a standard sysfs show function.

Remove the now unused types_attrs field in struct mdev_driver and the
support code for it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Link: https://lore.kernel.org/r/20220923092652.100656-14-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: consolidate all the available_instance sysfs into the core code

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

Every driver just print a number, simply add a method to the mdev_driver
to return it and provide a standard sysfs show function.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-13-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: consolidate all the name sysfs into the core code

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

Every driver just emits a static string, simply add a field to the
mdev_type for the driver to fill out or fall back to the sysfs name and
provide a standard sysfs show function.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jason Gunthorpe 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-12-hch@lst.de
Signed-off-by: Alex Williamson

vfio/mdev: consolidate all the device_api sysfs into the core code

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

Every driver just emits a static string, simply feed it through the ops
and provide a standard sysfs show function.

Signed-off-by: Jason Gunthorpe 
Signed-off-by: Christoph Hellwig 
Reviewed-by: Tony Krowiak 
Reviewed-by: Kevin Tian 
Reviewed-by: Kirti Wankhede 
Reviewed-by: Eric Farman 
Link: https://lore.kernel.org/r/20220923092652.100656-11-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