platform/x86: p2sb: Don't init until unassigned resources have been assigned

The P2SB could get an invalid BAR from the BIOS, and that won't be fixed
up until pcibios_assign_resources(), which is an fs_initcall().

- Move p2sb_fs_init() to an fs_initcall_sync(). This is still early
enough to avoid a race with any dependent drivers.

- Add a check for IORESOURCE_UNSET in p2sb_valid_resource() to catch
unset BARs going forward.

- Return error values from p2sb_fs_init() so that the 'initcall_debug'
cmdline arg provides useful data.

Signed-off-by: Ben Fradella <bfradell@netapp.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Klara Modin <klarasmodin@gmail.com>
Reviewed-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20240509164905.41016-1-bcfradella@proton.me
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: p2sb: Make p2sb_get_devfn() return void

p2sb_get_devfn() always succeeds, make it return void and
remove error checking from its callers.

Reviewed-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240305094500.23778-1-hdegoede@redhat.com

platform/x86: p2sb: On Goldmont only cache P2SB and SPI devfn BAR

On Goldmont p2sb_bar() only ever gets called for 2 devices, the actual P2SB
devfn 13,0 and the SPI controller which is part of the P2SB, devfn 13,2.

But the current p2sb code tries to cache BAR0 info for all of
devfn 13,0 to 13,7 . This involves calling pci_scan_single_device()
for device 13 functions 0-7 and the hw does not seem to like
pci_scan_single_device() getting called for some of the other hidden
devices. E.g. on an ASUS VivoBook D540NV-GQ065T this leads to continuous
ACPI errors leading to high CPU usage.

Fix this by only caching BAR0 info and thus only calling
pci_scan_single_device() for the P2SB and the SPI controller.

Fixes: 5913320eb0b3 ("platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe")
Reported-by: Danil Rybakov <danilrybakov249@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218531
Tested-by: Danil Rybakov <danilrybakov249@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240304134356.305375-2-hdegoede@redhat.com

platform/x86: p2sb: Use pci_resource_n() in p2sb_read_bar0()

Accesses to resource[] member of struct pci_dev shall be wrapped with
pci_resource_n() for future compatibility. Call the helper function in
p2sb_read_bar0().

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20240108062059.3583028-3-shinichiro.kawasaki@wdc.com
Tested-by Klara Modin <klarasmodin@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe

p2sb_bar() unhides P2SB device to get resources from the device. It
guards the operation by locking pci_rescan_remove_lock so that parallel
rescans do not find the P2SB device. However, this lock causes deadlock
when PCI bus rescan is triggered by /sys/bus/pci/rescan. The rescan
locks pci_rescan_remove_lock and probes PCI devices. When PCI devices
call p2sb_bar() during probe, it locks pci_rescan_remove_lock again.
Hence the deadlock.

To avoid the deadlock, do not lock pci_rescan_remove_lock in p2sb_bar().
Instead, do the lock at fs_initcall. Introduce p2sb_cache_resources()
for fs_initcall which gets and caches the P2SB resources. At p2sb_bar(),
refer the cache and return to the caller.

Before operating the device at P2SB DEVFN for resource cache, check
that its device class is PCI_CLASS_MEMORY_OTHER 0x0580 that PCH
specifications define. This avoids unexpected operation to other devices
at the same DEVFN.

Link: https://lore.kernel.org/linux-pci/6xb24fjmptxxn5js2fjrrddjae6twex5bjaftwqsuawuqqqydx@7cl3uik5ef6j/
Fixes: 9745fb07474f ("platform/x86/intel: Add Primary to Sideband (P2SB) bridge support")
Cc: stable@vger.kernel.org
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20240108062059.3583028-2-shinichiro.kawasaki@wdc.com
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Tested-by Klara Modin <klarasmodin@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Revert "platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe"

This reverts commit b28ff7a7c3245d7f62acc20f15b4361292fe4117.

The commit introduced P2SB device scan and resource cache during the
boot process to avoid deadlock. But it caused detection failure of
IDE controllers on old systems [1]. The IDE controllers on old systems
and P2SB devices on newer systems have same PCI DEVFN. It is suspected
the confusion between those two is the failure cause. Revert the change
at this moment until the proper solution gets ready.

Link: https://lore.kernel.org/platform-driver-x86/CABq1_vjfyp_B-f4LAL6pg394bP6nDFyvg110TOLHHb0x4aCPeg@mail.gmail.com/T/#m07b30468d9676fc5e3bb2122371121e4559bb383 [1]
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20240104114050.3142690-1-shinichiro.kawasaki@wdc.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

platform/x86: p2sb: Allow p2sb_bar() calls during PCI device probe

p2sb_bar() unhides P2SB device to get resources from the device. It
guards the operation by locking pci_rescan_remove_lock so that parallel
rescans do not find the P2SB device. However, this lock causes deadlock
when PCI bus rescan is triggered by /sys/bus/pci/rescan. The rescan
locks pci_rescan_remove_lock and probes PCI devices. When PCI devices
call p2sb_bar() during probe, it locks pci_rescan_remove_lock again.
Hence the deadlock.

To avoid the deadlock, do not lock pci_rescan_remove_lock in p2sb_bar().
Instead, do the lock at fs_initcall. Introduce p2sb_cache_resources()
for fs_initcall which gets and caches the P2SB resources. At p2sb_bar(),
refer the cache and return to the caller.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Fixes: 9745fb07474f ("platform/x86/intel: Add Primary to Sideband (P2SB) bridge support")
Cc: stable@vger.kernel.org
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/linux-pci/6xb24fjmptxxn5js2fjrrddjae6twex5bjaftwqsuawuqqqydx@7cl3uik5ef6j/
Link: https://lore.kernel.org/r/20231229063912.2517922-2-shinichiro.kawasaki@wdc.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

platform/x86: p2sb: Don't fail if unknown CPU is found

We have accessing P2SB from a very few places for quite known hardware.

When a new SoC appears in intel-family.h it's not obvious that it needs
to be added to p2sb.c as well. Instead, provide default BDF and refactor
p2sb_get_devfn() to always succeed. If in the future we would need to
exclude something, we may add a list of unsupported IDs.

Without this change the iTCO on Intel Comet Lake SoCs became unavailable:

i801_smbus 0000:00:1f.4: failed to create iTCO device

Fixes: 5c7b9167ddf8 ("i2c: i801: convert to use common P2SB accessor")
Reported-and-tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20221104154916.35231-1-andriy.shevchenko@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: p2sb: Fix UAF when caller uses resource name

We have to copy only selected fields from the original resource.
Because a PCI device will be removed immediately after getting
its resources, we may not use any allocated data, hence we may
not copy any pointers.

Consider the following scenario:

1/ a caller of p2sb_bar() gets the resource;

2/ the resource has been copied by platform_device_add_data()
in order to create a platform device;

3/ the platform device creation will call for the device driver's
->probe() as soon as a match found;

4/ the ->probe() takes given resources (see 2/) and tries to
access one of its field, i.e. 'name', in the
__devm_ioremap_resource() to create a pretty looking output;

5/ but the 'name' is a dangling pointer because p2sb_bar()
removed a PCI device, which 'name' had been copied to
the caller's memory.

6/ UAF (Use-After-Free) as a result.

Kudos to Mika for the initial analisys of the issue.

Fixes: 9745fb07474f ("platform/x86/intel: Add Primary to Sideband (P2SB) bridge support")
Reported-by: kernel test robot <oliver.sang@intel.com>
Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/linux-i2c/YvPCbnKqDiL2XEKp@xsang-OptiPlex-9020/
Link: https://lore.kernel.org/linux-i2c/YtjAswDKfiuDfWYs@xsang-OptiPlex-9020/
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220901113406.65876-1-andriy.shevchenko@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: p2sb: Fix UAF when caller uses resource name

We have to copy only selected fields from the original resource.
Because a PCI device will be removed immediately after getting
its resources, we may not use any allocated data, hence we may
not copy any pointers.

Consider the following scenario:

1/ a caller of p2sb_bar() gets the resource;

2/ the resource has been copied by platform_device_add_data()
in order to create a platform device;

3/ the platform device creation will call for the device driver's
->probe() as soon as a match found;

4/ the ->probe() takes given resources (see 2/) and tries to
access one of its field, i.e. 'name', in the
__devm_ioremap_resource() to create a pretty looking output;

5/ but the 'name' is a dangling pointer because p2sb_bar()
removed a PCI device, which 'name' had been copied to
the caller's memory.

6/ UAF (Use-After-Free) as a result.

Kudos to Mika for the initial analisys of the issue.

Fixes: 9745fb07474f ("platform/x86/intel: Add Primary to Sideband (P2SB) bridge support")
Reported-by: kernel test robot <oliver.sang@intel.com>
Suggested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/linux-i2c/YvPCbnKqDiL2XEKp@xsang-OptiPlex-9020/
Link: https://lore.kernel.org/linux-i2c/YtjAswDKfiuDfWYs@xsang-OptiPlex-9020/
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220901113406.65876-1-andriy.shevchenko@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

platform/x86: p2sb: Move out of X86_PLATFORM_DEVICES dependency

The P2SB library is used for various drivers, including server
platforms. That's why the dependency on X86_PLATFORM_DEVICES
seems superfluous.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20220718145328.14374-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>