The driver_override implementation is susceptible to a race condition when
different threads are reading vs. storing a different driver override.  Add
locking to avoid the race condition.

This is in close analogy to commit 62655397 ("driver core: platform:
fix race condition with driver_override") from Adrian Salido.

Fixes: 782a985d ("PCI: Introduce new device binding path using pci_dev.driver_override")
Signed-off-by: NNicolai Stange <nstange@suse.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org	# v3.16+

The "res" variable in pci_resource_io() is never used.  Remove it.
Signed-off-by: NShawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Now that we have a custom printf format specifier, convert users of
full_name() to use %pOF instead.  This is preparation for removing storing
of the full path string for each node.
Signed-off-by: NRob Herring <robh@kernel.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NTyrel Datwyler <tyreld@linux.vnet.ibm.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>

Add const to bin_attribute structures as they are only passed to the
functions sysfs_{remove/create}_bin_file. The corresponding arguments are
of type const, so declare the structures to be const.
Signed-off-by: NBhumika Goyal <bhumirks@gmail.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

attribute_groups are not supposed to change at runtime.  All functions
working with attribute_groups provided by <linux/sysfs.h> work with const
attribute_group.  So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   8480	   2024	      4	  10508	   290c	drivers/pci/pci-sysfs.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   8736	   1768	      4	  10508	   290c	drivers/pci/pci-sysfs.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Expose PCIe bridges attributes such as secondary bus number, subordinate
bus number, max link speed and link width, current link speed and link
width via sysfs in /sys/bus/pci/devices/...

This information is available via lspci, but that requires root privilege.
Signed-off-by: NWong Vee Khee <vee.khee.wong@ni.com>
Signed-off-by: NHui Chun Ong <hui.chun.ong@ni.com>
[bhelgaas: changelog, return errors early to unindent usual case, return
errors with same style throughout]
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Every method in struct device_driver or structures derived from it like
struct pci_driver MUST provide exclusion vs the driver's ->remove() method,
usually by using device_lock().

Protect use of pci_driver->sriov_configure() by holding the device lock
while calling it.

The PCI core sets the pci_dev->driver pointer in local_pci_probe() before
calling ->probe() and only clears it after ->remove().  This means driver's
->sriov_configure() callback will happily race with probe() and remove(),
most likely leading to BUGs, since drivers don't expect this.

Remove the iov lock completely, since we remove the last user.

[bhelgaas: changelog, thanks to Christoph for locking rule]
Link: http://lkml.kernel.org/r/20170522225023.14010-1-jakub.kicinski@netronome.comSigned-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Sometimes it is not desirable to bind SR-IOV VFs to drivers.  This can save
host side resource usage by VF instances that will be assigned to VMs.

Add a new PCI sysfs interface "sriov_drivers_autoprobe" to control that
from the PF.  To modify it, echo 0/n/N (disable probe) or 1/y/Y (enable
probe) to:

  /sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_drivers_autoprobe

Note that this must be done before enabling VFs.  The change will not take
effect if VFs are already enabled.  Simply, one can disable VFs by setting
sriov_numvfs to 0, choose whether to probe or not, and then re-enable the
VFs by restoring sriov_numvfs.

[bhelgaas: changelog, ABI doc]
Signed-off-by: NBodong Wang <bodong@mellanox.com>
Signed-off-by: NEli Cohen <eli@mellanox.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: NAlex Williamson <alex.williamson@redhat.com>

Starting to leave behind the legacy of the pci_mmap_page_range() interface
which takes "user-visible" BAR addresses.  This takes just the resource and
offset.

For now, both APIs coexist and depending on the platform, one is
implemented as a wrapper around the other.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

In all cases we know which BAR it is.  Passing it in means that arch code
(or generic code; watch this space) won't have to go looking for it again.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

We store the pointer, and then on *every* use of it we loop over the
device's resources to find out the index.  That's kind of silly.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

This is relatively esoteric, and knowing that we don't have it makes life
easier in some cases rather than just an eventual -EINVAL from
pci_mmap_page_range().
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Most of the almost-identical versions of pci_mmap_page_range() silently
ignore the 'write_combine' argument and give uncached mappings.

Yet we allow the PCIIOC_WRITE_COMBINE ioctl in /proc/bus/pci, expose the
'resourceX_wc' file in sysfs, and allow an attempted mapping to apparently
succeed.

To fix this, introduce a macro arch_can_pci_mmap_wc() which indicates
whether the platform can do a write-combining mapping.  On x86 this ends up
being pat_enabled(), while the few other platforms that support it can just
set it to a literal '1'.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

In the PCI_MMAP_PROCFS case when the address being passed by the user is a
'user visible' resource address based on the bus window, and not the actual
contents of the resource, that's what we need to be checking it against.
Signed-off-by: NDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org

Enabling/disabling SRIOV via sysfs by echo-ing multiple values
simultaneously:

  # echo 63 > /sys/class/net/ethX/device/sriov_numvfs&
  # echo 63 > /sys/class/net/ethX/device/sriov_numvfs

  # sleep 5

  # echo 0 > /sys/class/net/ethX/device/sriov_numvfs&
  # echo 0 > /sys/class/net/ethX/device/sriov_numvfs

results in the following bug:

  kernel BUG at drivers/pci/iov.c:495!
  invalid opcode: 0000 [#1] SMP
  CPU: 1 PID: 8050 Comm: bash Tainted: G   W   4.9.0-rc7-net-next #2092
  RIP: 0010:[<ffffffff813b1647>]
	    [<ffffffff813b1647>] pci_iov_release+0x57/0x60

  Call Trace:
   [<ffffffff81391726>] pci_release_dev+0x26/0x70
   [<ffffffff8155be6e>] device_release+0x3e/0xb0
   [<ffffffff81365ee7>] kobject_cleanup+0x67/0x180
   [<ffffffff81365d9d>] kobject_put+0x2d/0x60
   [<ffffffff8155bc27>] put_device+0x17/0x20
   [<ffffffff8139c08a>] pci_dev_put+0x1a/0x20
   [<ffffffff8139cb6b>] pci_get_dev_by_id+0x5b/0x90
   [<ffffffff8139cca5>] pci_get_subsys+0x35/0x40
   [<ffffffff8139ccc8>] pci_get_device+0x18/0x20
   [<ffffffff8139ccfb>] pci_get_domain_bus_and_slot+0x2b/0x60
   [<ffffffff813b09e7>] pci_iov_remove_virtfn+0x57/0x180
   [<ffffffff813b0b95>] pci_disable_sriov+0x65/0x140
   [<ffffffffa00a1af7>] ixgbe_disable_sriov+0xc7/0x1d0 [ixgbe]
   [<ffffffffa00a1e9d>] ixgbe_pci_sriov_configure+0x3d/0x170 [ixgbe]
   [<ffffffff8139d28c>] sriov_numvfs_store+0xdc/0x130
  ...
  RIP  [<ffffffff813b1647>] pci_iov_release+0x57/0x60

Use the existing mutex lock to protect each enable/disable operation.
Signed-off-by: NEmil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NGavin Shan <gwshan@linux.vnet.ibm.com>
CC: Alexander Duyck <alexander.h.duyck@intel.com>

Currently the revision isn't available via sysfs/libudev thus if one wants
to know the value one needs to read through the config file, which can be
quite time-consuming because it wakes/powers up the device.

There are at least two userspace components which could make use the new
file: libpciaccess and libdrm.  The former wakes up _every_ PCI device,
which can be observed via glxinfo when using Mesa 10.0+ drivers.  The
latter, in association with Mesa 13.0, can lead to 2-3 second delays while
starting firefox, thunderbird or chromium.

Link: https://bugs.freedesktop.org/show_bug.cgi?id=98502Tested-by: NMauro Santos <registo.mailling@gmail.com>
Signed-off-by: NEmil Velikov <emil.velikov@collabora.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch
CC: Greg KH <gregkh@linuxfoundation.org>

Currently the Linux PCI core does not touch power state of PCI bridges and
PCIe ports when system suspend is entered.  Leaving them in D0 consumes
power unnecessarily and may prevent the CPU from entering deeper C-states.

With recent PCIe hardware we can power down the ports to save power given
that we take into account few restrictions:

  - The PCIe port hardware is recent enough, starting from 2015.

  - Devices connected to PCIe ports are effectively in D3cold once the port
    is transitioned to D3 (the config space is not accessible anymore and
    the link may be powered down).

  - Devices behind the PCIe port need to be allowed to transition to D3cold
    and back.  There is a way both drivers and userspace can forbid this.

  - If the device behind the PCIe port is capable of waking the system it
    needs to be able to do so from D3cold.

This patch adds a new flag to struct pci_device called 'bridge_d3'.  This
flag is set and cleared by the PCI core whenever there is a change in power
management state of any of the devices behind the PCIe port.  When system
later on is suspended we only need to check this flag and if it is true
transition the port to D3 otherwise we leave it in D0.

Also provide override mechanism via command line parameter
"pcie_port_pm=[off|force]" that can be used to disable or enable the
feature regardless of the BIOS manufacturing date.
Tested-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NMika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

iomem_is_exclusive() requires a CPU physical address, but on some arches we
supplied a PCI bus address instead.

On most arches, pci_resource_to_user(res) returns "res->start", which is a
CPU physical address.  But on microblaze, mips, powerpc, and sparc, it
returns the PCI bus address corresponding to "res->start".

The result is that pci_mmap_resource() may fail when it shouldn't (if the
bus address happens to match an existing resource), or it may succeed when
it should fail (if the resource is exclusive but the bus address doesn't
match it).

Call iomem_is_exclusive() with "res->start", which is always a CPU physical
address, not the result of pci_resource_to_user().

Fixes: e8de1481 ("resource: allow MMIO exclusivity for device drivers")
Suggested-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Arjan van de Ven <arjan@linux.intel.com>

The PCI config access checked the file capabilities correctly, but used
the itnernal security capability check rather than the helper function
that is actually meant for that.

The security_capable() has unusual return values and is not meant to be
used elsewhere (the only other use is in the capability checking
functions that we actually intend people to use, and this odd PCI usage
really stood out when looking around the capability code.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Return error immediately to simplify the control flow in pci_create_attr().
No functional change intended.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

If sysfs_create_bin_file() fails, pci_create_attr() leaks the struct
bin_attribute it allocated previously.

Free the struct bin_attribute if pci_create_attr() fails.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

The value of pdev->rom_attr is the definitive indicator of the fact that
we're created a sysfs attribute.  Check that rather than rom_size, which is
only used incidentally when deciding whether to create a sysfs attribute.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

When pci_create_sysfs_dev_files() created the "rom" sysfs file, it set the
sysfs file size to the actual size of a ROM BAR, or if there was no ROM BAR
but the platform provided a shadow copy in RAM, to 0x20000.  0x20000 is an
arch-specific length that should not be baked into the PCI core.

Every place that sets IORESOURCE_ROM_SHADOW also sets the size of the
PCI_ROM_RESOURCE, so use the resource length always.
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

PCI-2.2 VPD entries have a maximum size of 32k, but might actually be
smaller than that.  To figure out the actual size one has to read the VPD
area until the 'end marker' is reached.

Per spec, reading outside of the VPD space is "not allowed."  In practice,
it may cause simple read errors or even crash the card.  To make matters
worse not every PCI card implements this properly, leaving us with no 'end'
marker or even completely invalid data.

Try to determine the size of the VPD data when it's first accessed.  If no
valid data can be read an I/O error will be returned when reading or
writing the sysfs attribute.

As the amount of VPD data is unknown initially the size of the sysfs
attribute will always be set to '0'.

[bhelgaas: changelog, use 0/1 (not false/true) for bitfield, tweak
pci_vpd_pci22_read() error checking]
Tested-by: NShane Seymour <shane.seymour@hpe.com>
Tested-by: NBabu Moger <babu.moger@oracle.com>
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>

It is not always possible to determine the actual size of the VPD
data, so allow access to them if the size is set to '0'.
Tested-by: NShane Seymour <shane.seymour@hpe.com>
Tested-by: NBabu Moger <babu.moger@oracle.com>
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>

Use kobj_to_dev() instead of open-coding it.
Signed-off-by: NGeliang Tang <geliangtang@163.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

If a device quirk modifies the pci_dev->cfg_size to be less than
PCI_CFG_SPACE_EXP_SIZE (4096), but greater than PCI_CFG_SPACE_SIZE (256),
the PCI sysfs interface truncates the readable size to PCI_CFG_SPACE_SIZE.

Allow sysfs access to config space up to cfg_size, even if the device
doesn't support the entire 4096-byte PCIe config space.

Note that pci_read_config() and pci_write_config() limit access to
dev->cfg_size even though pcie_config_attr contains 4096 (the maximum
size).
Signed-off-by: NJason S. McMullan <jason.mcmullan@netronome.com>
[simon: edited changelog]
Signed-off-by: NSimon Horman <simon.horman@netronome.com>
[bhelgaas: more changelog edits]
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Commit 12669631 ("PCI: Prevent out of bounds access in numa_node
override") missed that the user-provided node could also be negative.
Handle this case as well to avoid out-of-bounds accesses to the
node_states[] array.  However, allow the special value -1, i.e.
NUMA_NO_NODE, to be able to set the 'no specific node' configuration.

Fixes: 12669631 ("PCI: Prevent out of bounds access in numa_node override")
Fixes: 63692df1 ("PCI: Allow numa_node override via sysfs")
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Sasha Levin <sasha.levin@oracle.com>
CC: Prarit Bhargava <prarit@redhat.com>
CC: stable@vger.kernel.org	# v3.19+

63692df1 ("PCI: Allow numa_node override via sysfs") didn't check that
the numa node provided by userspace is valid.  Passing a node number too
high would attempt to access invalid memory and trigger a kernel panic.

Fixes: 63692df1 ("PCI: Allow numa_node override via sysfs")
Signed-off-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v3.19+

When printing the driver_override parameter when it is 4095 and 4094 bytes
long, the printing code would access invalid memory because we need count+1
bytes for printing.

Fixes: 782a985d ("PCI: Introduce new device binding path using pci_dev.driver_override")
Signed-off-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NAlex Williamson <alex.williamson@redhat.com>
CC: stable@vger.kernel.org	# v3.16+
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Alexander Graf <agraf@suse.de>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

After commit b2b49ccb (PM: Kconfig: Set PM_RUNTIME if PM_SLEEP is
selected) PM_RUNTIME is always set if PM is set, so quite a few
depend on CONFIG_PM.

Replace CONFIG_PM_RUNTIME with CONFIG_PM in the PCI core code.
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NKevin Hilman <khilman@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Many sysfs *_show function use cpu{list,mask}_scnprintf to copy cpumap
to the buffer aligned to PAGE_SIZE, append '\n' and '\0' to return null
terminated buffer with newline.

This patch creates a new helper function cpumap_print_to_pagebuf in
cpumask.h using newly added bitmap_print_to_pagebuf and consolidates
most of those sysfs functions using the new helper function.
Signed-off-by: NSudeep Holla <sudeep.holla@arm.com>
Suggested-by: NStephen Boyd <sboyd@codeaurora.org>
Tested-by: NStephen Boyd <sboyd@codeaurora.org>
Acked-by: N"Rafael J. Wysocki" <rjw@rjwysocki.net>
Acked-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: x86@kernel.org
Cc: linux-acpi@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

NUMA systems with ACPI normally describe the physical topology via _PXM
methods.  But many BIOSes don't implement _PXM, which leaves the kernel
with no way to discover the device topology, which reduces performance
because we can't put memory and processes close to the device.

The NUMA node of a PCI device is already exported in the sysfs "numa_node"
file.  Make that file writable so users can workaround the lack of _PXM
methods in the BIOS.  For example:

  echo 3 > /sys/devices/pci0000:ff/0000:03:1f.3/numa_node

sets the node for PCI device 0000:03:1f.3.

Writing the file emits a FW_BUG warning to encourage users to request
firmware updates.  It also taints the kernel with TAINT_FIRMWARE_WORKAROUND
because overriding the node incorrectly can cause performance issues.

[bhelgaas: changelog, documentation text]
Signed-off-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: Myron Stowe <mstowe@redhat.com>
CC: Alexander Ducyk <alexander.h.duyck@redhat.com>
CC: Jiang Liu <jiang.liu@linux.intel.com>

Back in commit 5136b2da ("PCI: convert bus code to use dev_groups"),
I misstyped the 'enable' sysfs filename as 'enabled', which broke the
userspace API.  This patch fixes that issue by renaming the file back.

Fixes: 5136b2da ("PCI: convert bus code to use dev_groups")
Reported-by: NJeff Epler <jepler@unpythonic.net>
Tested-by: Jeff Epler <jepler@unpythonic.net>	# on v3.14-rt
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# 3.13

The "msi_bus" sysfs file for bridges sets a bus flag to allow or disallow
future driver requests for MSI or MSI-X.  Previously, the sysfs file
existed for endpoints but did nothing.

Add "msi_bus" support for endpoints, so an administrator can prevent the
use of MSI and MSI-X for individual devices.

Note that as for bridges, these changes only affect future driver requests
for MSI or MSI-X, so drivers may need to be reloaded.

Add documentation for the "msi_bus" sysfs file.

[bhelgaas: changelog, comments, add "subordinate", add endpoint printk,
rework bus_flags setting, make bus_flags printk unconditional]
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Some implementations of modprobe fail to load the driver for a PCI device
automatically because the "interface" part of the modalias from the kernel
is lowercase, and the modalias from file2alias is uppercase.

The "interface" is the low-order byte of the Class Code, defined in PCI
r3.0, Appendix D.  Most interface types defined in the spec do not use
alpha characters, so they won't be affected.  For example, 00h, 01h, 10h,
20h, etc. are unaffected.

Print the "interface" byte of the Class Code in uppercase hex, as we
already do for the Vendor ID, Device ID, Class, etc.

[bhelgaas: changelog]
Signed-off-by: NRicardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: stable@vger.kernel.org

Merge quoted strings that are broken across lines into a single entity.
The compiler merges them anyway, but checkpatch complains about it, and
merging them makes it easier to grep for strings.

No functional change.

[bhelgaas: changelog, do the same for everything under drivers/pci]
Signed-off-by: NRyan Desfosses <ryan@desfo.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Fix various whitespace errors.

No functional change.

[bhelgaas: fix other similar problems]
Signed-off-by: NRyan Desfosses <ryan@desfo.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

The driver_override field allows us to specify the driver for a device
rather than relying on the driver to provide a positive match of the
device.  This shortcuts the existing process of looking up the vendor and
device ID, adding them to the driver new_id, binding the device, then
removing the ID, but it also provides a couple advantages.

First, the above existing process allows the driver to bind to any device
matching the new_id for the window where it's enabled.  This is often not
desired, such as the case of trying to bind a single device to a meta
driver like pci-stub or vfio-pci.  Using driver_override we can do this
deterministically using:

  echo pci-stub > /sys/bus/pci/devices/0000:03:00.0/driver_override
  echo 0000:03:00.0 > /sys/bus/pci/devices/0000:03:00.0/driver/unbind
  echo 0000:03:00.0 > /sys/bus/pci/drivers_probe

Previously we could not invoke drivers_probe after adding a device to
new_id for a driver as we get non-deterministic behavior whether the driver
we intend or the standard driver will claim the device.  Now it becomes a
deterministic process, only the driver matching driver_override will probe
the device.

To return the device to the standard driver, we simply clear the
driver_override and reprobe the device:

  echo > /sys/bus/pci/devices/0000:03:00.0/driver_override
  echo 0000:03:00.0 > /sys/bus/pci/devices/0000:03:00.0/driver/unbind
  echo 0000:03:00.0 > /sys/bus/pci/drivers_probe

Another advantage to this approach is that we can specify a driver override
to force a specific binding or prevent any binding.  For instance when an
IOMMU group is exposed to userspace through VFIO we require that all
devices within that group are owned by VFIO.  However, devices can be
hot-added into an IOMMU group, in which case we want to prevent the device
from binding to any driver (override driver = "none") or perhaps have it
automatically bind to vfio-pci.  With driver_override it's a simple matter
for this field to be set internally when the device is first discovered to
prevent driver matches.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: NAlexander Graf <agraf@suse.de>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove pcibios_add_platform_entries().  Architecture-specific attributes
can be achieved by setting pdev->dev.groups.

Link: https://lkml.kernel.org/r/alpine.LFD.2.11.1404141101500.1529@denkbrettSigned-off-by: NSebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>