linux-stable.git/drivers/pci/hotplug, branch v4.18.2

PCI: Fix is_added/is_busmaster race condition

2018-07-31T16:27:54+00:00

When a PCI device is detected, pdev->is_added is set to 1 and proc and
sysfs entries are created.

When the device is removed, pdev->is_added is checked for one and then
device is detached with clearing of proc and sys entries and at end,
pdev->is_added is set to 0.

is_added and is_busmaster are bit fields in pci_dev structure sharing same
memory location.

A strange issue was observed with multiple removal and rescan of a PCIe
NVMe device using sysfs commands where is_added flag was observed as zero
instead of one while removing device and proc,sys entries are not cleared.
This causes issue in later device addition with warning message
"proc_dir_entry" already registered.

Debugging revealed a race condition between the PCI core setting the
is_added bit in pci_bus_add_device() and the NVMe driver reset work-queue
setting the is_busmaster bit in pci_set_master().  As these fields are not
handled atomically, that clears the is_added bit.

Move the is_added bit to a separate private flag variable and use atomic
functions to set and retrieve the device addition state.  This avoids the
race because is_added no longer shares a memory location with is_busmaster.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=200283
Signed-off-by: Hari Vyas 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Lukas Wunner 
Acked-by: Michael Ellerman

PCI: shpchp: Manage SHPC unconditionally on non-ACPI systems

2018-06-26T13:22:45+00:00

An SHPC can be operated either by platform firmware or by the OS.  The OS
uses a host bridge ACPI _OSC method to negotiate for control of SHPC.  If
firmware wants to prevent an OS from operating an SHPC, it must supply an
_OSC method that declines to grant SHPC ownership to the OS.

If acpi_pci_find_root() returns NULL, it means there's no ACPI host bridge
device (PNP0A03 or PNP0A08) and hence no _OSC method, so the OS is always
allowed to manage the SHPC.

Fix a NULL pointer dereference when CONFIG_ACPI=y but the current
hardware/firmware platform doesn't support ACPI.  In that case,
acpi_get_hp_hw_control_from_firmware() is implemented but
acpi_pci_find_root() returns NULL.

Fixes: 90cc0c3cc709 ("PCI: shpchp: Add shpchp_is_native()")
Link: https://lkml.kernel.org/r/20180621164715.28160-1-marc.zyngier@arm.com
Reported-by: Marc Zyngier 
Tested-by: Marc Zyngier 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Mika Westerberg

Merge branch 'pci/hotplug'

2018-06-06T21:10:10+00:00

  - fix use-before-set error in ibmphp (Dan Carpenter)

  - fix pciehp timeouts caused by Command Completed errata (Bjorn Helgaas)

  - fix refcounting in pnv_php hotplug (Julia Lawall)

  - clear pciehp Presence Detect and Data Link Layer Status Changed on
    resume so we don't miss hotplug events (Mika Westerberg)

  - only request pciehp control if we support it, so platform can use ACPI
    hotplug otherwise (Mika Westerberg)

  - convert SHPC to be builtin only (Mika Westerberg)

  - request SHPC control via _OSC if we support it (Mika Westerberg)

  - simplify SHPC handoff from firmware (Mika Westerberg)

* pci/hotplug:
  PCI: Improve "partially hidden behind bridge" log message
  PCI: Improve pci_scan_bridge() and pci_scan_bridge_extend() doc
  PCI: Move resource distribution for single bridge outside loop
  PCI: Account for all bridges on bus when distributing bus numbers
  ACPI / hotplug / PCI: Drop unnecessary parentheses
  ACPI / hotplug / PCI: Mark stale PCI devices disconnected
  ACPI / hotplug / PCI: Don't scan bridges managed by native hotplug
  PCI: hotplug: Add hotplug_is_native()
  PCI: shpchp: Add shpchp_is_native()
  PCI: shpchp: Fix AMD POGO identification
  PCI: shpchp: Use dev_printk() for OSHP-related messages
  PCI: shpchp: Remove get_hp_hw_control_from_firmware() wrapper
  PCI: shpchp: Remove acpi_get_hp_hw_control_from_firmware() flags
  PCI: shpchp: Rely on previous _OSC results
  PCI: shpchp: Request SHPC control via _OSC when adding host bridge
  PCI: shpchp: Convert SHPC to be builtin only
  PCI: pciehp: Make pciehp_is_native() stricter
  PCI: pciehp: Rename host->native_hotplug to host->native_pcie_hotplug
  PCI: pciehp: Request control of native hotplug only if supported
  PCI: pciehp: Clear Presence Detect and Data Link Layer Status Changed on resume
  PCI: pnv_php: Add missing of_node_put()
  PCI: pciehp: Add quirk for Command Completed errata
  PCI: Add Qualcomm vendor ID
  PCI: ibmphp: Fix use-before-set in get_max_bus_speed()

# Conflicts:
#	drivers/acpi/pci_root.c

ACPI / hotplug / PCI: Drop unnecessary parentheses

2018-06-04T17:08:06+00:00

Remove unnecessary parentheses.

Signed-off-by: Mika Westerberg 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Rafael J. Wysocki

ACPI / hotplug / PCI: Mark stale PCI devices disconnected

2018-06-04T17:08:06+00:00

Following PCIehp mark the unplugged PCI devices disconnected.  This makes
sure PCI core code leaves the now missing hardware registers alone.

Signed-off-by: Mika Westerberg 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Rafael J. Wysocki 
Reviewed-by: Andy Shevchenko

ACPI / hotplug / PCI: Don't scan bridges managed by native hotplug

2018-06-04T17:08:06+00:00

When acpiphp re-enumerates a PCI hierarchy because of an ACPI Notify()
event, we should skip bridges managed by native hotplug (pciehp or shpchp).
We don't want to scan below a native hotplug bridge until the hotplug
controller generates a hot-add event.

A typical scenario is a Root Port leading to a Thunderbolt host router that
remains powered off until something is connected to it.  See [1] for the
lspci details.

  1. Before something is connected, only the Root Port exists.  It has
     PCI_EXP_SLTCAP_HPC set and pciehp is responsible for hotplug:

       00:1b.0 Root Port (HotPlug+)

  2. When a USB-C or Thunderbolt device is connected, the Switch in the
     Thunderbolt host router is powered up, the Root Port signals a hotplug
     add event and pciehp enumerates the Switch:

       01:00.0 Switch Upstream Port   to [bus 02-39]
       02:00.0 Switch Downstream Port to [bus 03]    (HotPlug-, to NHI)
       02:01.0 Switch Downstream Port to [bus 04-38] (HotPlug+, to Thunderbolt connector)
       02:02.0 Switch Downstream Port to [bus 39]    (HotPlug-, to xHCI)

     The 02:00.0 and 02:02.0 Ports lead to Endpoints that are not powered
     up yet.  The Ports have PCI_EXP_SLTCAP_HPC cleared, so pciehp doesn't
     handle hotplug for them and we assign minimal resources to them.

     The 02:01.0 Port has PCI_EXP_SLTCAP_HPC set, so pciehp handles native
     hotplug events for it.

  3. The BIOS powers up the xHCI controller.  If a Thunderbolt device was
     connected (not just a USB-C device), it also powers up the NHI.  Then
     it sends an ACPI Notify() to the Root Port, and acpiphp enumerates the
     new device(s):

       03:00.0 Thunderbolt Host Controller (NHI) Endpoint
       39:00.0 xHCI Endpoint

  4. If a Thunderbolt device was connected, the host router firmware uses
     the NHI to set up Thunderbolt tunnels and triggers a native hotplug
     event (via 02:01.0 in this example).  Then pciehp enumerates the new
     Thunderbolt devices:

       04:00.0 Switch Upstream Port   to [bus 05-38]
       05:01.0 Switch Downstream Port to [bus 06-09] (HotPlug-)
       05:04.0 Switch Downstream Port to [bus 0a-38] (HotPlug+)

     In this example, 05:01.0 leads to another Switch and some NICs.  This
     subtree is static, so 05:01.0 doesn't support hotplug and has
     PCI_EXP_SLTCAP_HPC cleared.

In step 3, acpiphp previously enumerated everything below the Root Port,
including things below the 02:01.0 Port.  We don't want that because pciehp
expects to manage hotplug below that Port, and firmware on the host router
may be in the middle of configuring its Link so it may not be ready yet.

To make this work better with the native PCIe (pciehp) and standard PCI
(shpchp) hotplug drivers, we let them handle all slot management and
resource allocation for hotplug bridges and restrict ACPI hotplug to
non-hotplug bridges.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=199581#c5
Link: https://lkml.kernel.org/r/20180529160155.1738-1-mika.westerberg@linux.intel.com
Signed-off-by: Mika Westerberg 
[bhelgaas: changelog, use hotplug_is_native() instead of
dev->is_hotplug_bridge]
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Rafael J. Wysocki 
Reviewed-by: Andy Shevchenko

PCI: shpchp: Add shpchp_is_native()

2018-06-04T17:08:06+00:00

In the same way we do for pciehp, add shpchp_is_native(), which returns
true if the bridge should be handled by the native SHPC driver.  Then
convert the driver to use this function.

Signed-off-by: Mika Westerberg 
Signed-off-by: Bjorn Helgaas

PCI: shpchp: Fix AMD POGO identification

2018-06-04T17:07:31+00:00

The fix for an AMD POGO erratum related to SHPC incorrectly identified the
device.  The workaround should be applied only for AMD POGO devices, but it
was instead applied to:

  - all AMD bridges, and
  - all devices from any vendor with device ID 0x7458

Fixes: 53044f357448 ("[PATCH] PCI Hotplug: shpchp: AMD POGO errata fix")
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Mika Westerberg 
Reviewed-by: Rafael J. Wysocki

PCI: shpchp: Use dev_printk() for OSHP-related messages

2018-06-02T05:18:28+00:00

Use dev_printk() for messages related to requesting control of SHPC hotplug
via the OSHP method.

Signed-off-by: Bjorn Helgaas 
Reviewed-by: Mika Westerberg 
Reviewed-by: Rafael J. Wysocki

PCI: shpchp: Remove get_hp_hw_control_from_firmware() wrapper

2018-06-02T05:18:28+00:00

get_hp_hw_control_from_firmware() is a trivial wrapper around
acpi_get_hp_hw_control_from_firmware(), probably intended to be generic in
case other firmware needed similar OS/platform negotiation.

Remove get_hp_hw_control_from_firmware() and call
acpi_get_hp_hw_control_from_firmware() directly.  Add a stub for
acpi_get_hp_hw_control_from_firmware() for the non-ACPI case.

Signed-off-by: Mika Westerberg 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Rafael J. Wysocki