linux.git/drivers/pci/iov.c, branch v6.6.13

PCI/IOV: Use pci_dev_id() to simplify the code

2023-08-07T21:15:39+00:00

When we have a struct pci_dev *, use pci_dev_id() instead of manually
composing the ID with PCI_DEVID() from dev->bus->number and dev->devfn.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/20230807134858.116051-4-wangxiongfeng2@huawei.com
Signed-off-by: Xiongfeng Wang 
Signed-off-by: Bjorn Helgaas

PCI/IOV: Enlarge virtfn sysfs name buffer

2023-01-18T16:54:41+00:00

The sysfs link name "virtfn%u" constructed by pci_iov_sysfs_link() requires
17 bytes to contain the longest possible string.  Increase VIRTFN_ID_LEN to
accommodate that.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

[bhelgaas: commit log, comment at #define]
Fixes: dd7cc44d0bce ("PCI: add SR-IOV API for Physical Function driver")
Link: https://lore.kernel.org/r/20221218033347.23743-1-gremlin@altlinux.org
Signed-off-by: Alexey V. Vissarionov 
Signed-off-by: Bjorn Helgaas

PCI/IOV: Fix wrong kernel-doc identifier

2022-03-07T19:06:10+00:00

Replace "-" to be ":" in comment section to be aligned with
kernel-doc format.

drivers/pci/iov.c:67: warning: Function parameter or member 'dev' not described in 'pci_iov_get_pf_drvdata'
drivers/pci/iov.c:67: warning: Function parameter or member 'pf_driver' not described in 'pci_iov_get_pf_drvdata'

Fixes: a7e9f240c0da ("PCI/IOV: Add pci_iov_get_pf_drvdata() to allow VF reaching the drvdata of a PF")
Reported-by: Stephen Rothwell 
Signed-off-by: Leon Romanovsky 
Acked-by: Randy Dunlap 
Acked-by: Bjorn Helgaas 
Link: https://lore.kernel.org/r/8cecf7df45948a256dc56148cf9e87b2f2bb4198.1646652504.git.leonro@nvidia.com
Signed-off-by: Alex Williamson

PCI/IOV: Add pci_iov_get_pf_drvdata() to allow VF reaching the drvdata of a PF

2022-02-27T09:40:58+00:00

There are some cases where a SR-IOV VF driver will need to reach into and
interact with the PF driver. This requires accessing the drvdata of the PF.

Provide a function pci_iov_get_pf_drvdata() to return this PF drvdata in a
safe way. Normally accessing a drvdata of a foreign struct device would be
done using the device_lock() to protect against device driver
probe()/remove() races.

However, due to the design of pci_enable_sriov() this will result in a
ABBA deadlock on the device_lock as the PF's device_lock is held during PF
sriov_configure() while calling pci_enable_sriov() which in turn holds the
VF's device_lock while calling VF probe(), and similarly for remove.

This means the VF driver can never obtain the PF's device_lock.

Instead use the implicit locking created by pci_enable/disable_sriov(). A
VF driver can access its PF drvdata only while its own driver is attached,
and the PF driver can control access to its own drvdata based on when it
calls pci_enable/disable_sriov().

To use this API the PF driver will setup the PF drvdata in the probe()
function. pci_enable_sriov() is only called from sriov_configure() which
cannot happen until probe() completes, ensuring no VF races with drvdata
setup.

For removal, the PF driver must call pci_disable_sriov() in its remove
function before destroying any of the drvdata. This ensures that all VF
drivers are unbound before returning, fencing concurrent access to the
drvdata.

The introduction of a new function to do this access makes clear the
special locking scheme and the documents the requirements on the PF/VF
drivers using this.

Link: https://lore.kernel.org/all/20220224142024.147653-5-yishaih@nvidia.com
Signed-off-by: Jason Gunthorpe 
Acked-by: Bjorn Helgaas 
Signed-off-by: Yishai Hadas 
Signed-off-by: Leon Romanovsky

PCI/IOV: Add pci_iov_vf_id() to get VF index

2022-02-27T09:38:51+00:00

The PCI core uses the VF index internally, often called the vf_id,
during the setup of the VF, eg pci_iov_add_virtfn().

This index is needed for device drivers that implement live migration
for their internal operations that configure/control their VFs.

Specifically, mlx5_vfio_pci driver that is introduced in coming patches
from this series needs it and not the bus/device/function which is
exposed today.

Add pci_iov_vf_id() which computes the vf_id by reversing the math that
was used to create the bus/device/function.

Link: https://lore.kernel.org/all/20220224142024.147653-2-yishaih@nvidia.com
Signed-off-by: Jason Gunthorpe 
Acked-by: Bjorn Helgaas 
Signed-off-by: Yishai Hadas 
Signed-off-by: Leon Romanovsky

Revert "PCI: Use to_pci_driver() instead of pci_dev->driver"

2021-11-11T19:36:22+00:00

This reverts commit 2a4d9408c9e8b6f6fc150c66f3fef755c9e20d4a.

Robert reported a NULL pointer dereference caused by the PCI core
(local_pci_probe()) calling the i2c_designware_pci driver's
.runtime_resume() method before the .probe() method.  i2c_dw_pci_resume()
depends on initialization done by i2c_dw_pci_probe().

Prior to 2a4d9408c9e8 ("PCI: Use to_pci_driver() instead of
pci_dev->driver"), pci_pm_runtime_resume() avoided calling the
.runtime_resume() method because pci_dev->driver had not been set yet.

2a4d9408c9e8 and b5f9c644eb1b ("PCI: Remove struct pci_dev->driver"),
removed pci_dev->driver, replacing it by device->driver, which *has* been
set by this time, so pci_pm_runtime_resume() called the .runtime_resume()
method when it previously had not.

Fixes: 2a4d9408c9e8 ("PCI: Use to_pci_driver() instead of pci_dev->driver")
Link: https://lore.kernel.org/linux-i2c/CAP145pgdrdiMAT7=-iB1DMgA7t_bMqTcJL4N0=6u8kNY3EU0dw@mail.gmail.com/
Reported-by: Robert Święcki 
Tested-by: Robert Święcki 
Signed-off-by: Bjorn Helgaas

Merge branch 'pci/sysfs'

2021-11-05T16:28:46+00:00

- Check for CAP_SYS_ADMIN before validating sysfs user input, not after
  (Krzysztof Wilczyński)

- Always return -EINVAL from sysfs "store" functions for invalid user input
  instead of -EINVAL sometimes and -ERANGE others (Krzysztof Wilczyński)

- Use kstrtobool() directly instead of the strtobool() wrapper (Krzysztof
  Wilczyński)

* pci/sysfs:
  PCI: Use kstrtobool() directly, sans strtobool() wrapper
  PCI/sysfs: Return -EINVAL consistently from "store" functions
  PCI/sysfs: Check CAP_SYS_ADMIN before parsing user input

# Conflicts:
#	drivers/pci/iov.c

PCI: Use to_pci_driver() instead of pci_dev->driver

2021-10-18T14:20:15+00:00

Struct pci_driver contains a struct device_driver, so for PCI devices, it's
easy to convert a device_driver * to a pci_driver * with to_pci_driver().
The device_driver * is in struct device, so we don't need to also keep
track of the pci_driver * in struct pci_dev.

Replace pci_dev->driver with to_pci_driver().  This is a step toward
removing pci_dev->driver.

[bhelgaas: split to separate patch]
Link: https://lore.kernel.org/r/20211004125935.2300113-11-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König 
Signed-off-by: Bjorn Helgaas

PCI/sysfs: Return -EINVAL consistently from "store" functions

2021-09-28T22:47:04+00:00

Most of the "store" functions that handle userspace input via sysfs return
-EINVAL should the value fail validation and/or type conversion.  This
error code is a clear message to userspace that the value is not a valid
input.

However, some of the "show" functions return input parsing error codes
as-is, which may be either -EINVAL or -ERANGE.  The former would often be
from kstrtobool(), and the latter typically from other kstr*() functions
such as kstrtou8(), kstrtou32(), kstrtoint(), etc.

-EINVAL is commonly returned as the error code to indicate that the value
provided is invalid, but -ERANGE is not very useful in userspace.

Therefore, normalize the return error code to be -EINVAL for when the
validation and/or type conversion fails.

Link: https://lore.kernel.org/r/20210915230127.2495723-2-kw@linux.com
Signed-off-by: Krzysztof Wilczyński 
Signed-off-by: Bjorn Helgaas

Merge branch 'pci/virtualization'

2021-07-06T15:56:26+00:00

- Clarify error message for unbound devices (Moritz Fischer)

* pci/virtualization:
  PCI/IOV: Clarify error message for unbound devices