This is done by adding a zpci_hot_reset_device() call which does a low
level reset of the PCI function without changing its higher level
function state. This way it can be used while the zPCI function is bound
to a driver and with DMA tables being controlled either through the
IOMMU or DMA APIs which is prohibited when using zpci_disable_device()
as that drop existing DMA translations.

As this reset, unlike a normal FLR, also calls zpci_clear_irq() we need
to implement arch_restore_msi_irqs() and make sure we re-enable IRQs for
the PCI function if they were previously disabled.

Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Pull pci updates from Bjorn Helgaas:
 "Enumeration:
   - Conserve IRQs by setting up portdrv IRQs only when there are users
     (Jan Kiszka)
   - Rework and simplify _OSC negotiation for control of PCIe features
     (Joerg Roedel)
   - Remove struct pci_dev.driver pointer since it's redundant with the
     struct device.driver pointer (Uwe Kleine-König)

  Resource management:
   - Coalesce contiguous host bridge apertures from _CRS to accommodate
     BARs that cover more than one aperture (Kai-Heng Feng)

  Sysfs:
   - Check CAP_SYS_ADMIN before parsing user input (Krzysztof
     Wilczyński)
   - Return -EINVAL consistently from "store" functions (Krzysztof
     Wilczyński)
   - Use sysfs_emit() in endpoint "show" functions to avoid buffer
     overruns (Kunihiko Hayashi)

  PCIe native device hotplug:
   - Ignore Link Down/Up caused by resets during error recovery so
     endpoint drivers can remain bound to the device (Lukas Wunner)

  Virtualization:
   - Avoid bus resets on Atheros QCA6174, where they hang the device
     (Ingmar Klein)
   - Work around Pericom PI7C9X2G switch packet drop erratum by using
     store and forward mode instead of cut-through (Nathan Rossi)
   - Avoid trying to enable AtomicOps on VFs; the PF setting applies to
     all VFs (Selvin Xavier)

  MSI:
   - Document that /sys/bus/pci/devices/.../irq contains the legacy INTx
     interrupt or the IRQ of the first MSI (not MSI-X) vector (Barry
     Song)

  VPD:
   - Add pci_read_vpd_any() and pci_write_vpd_any() to access anywhere
     in the possible VPD space; use these to simplify the cxgb3 driver
     (Heiner Kallweit)

  Peer-to-peer DMA:
   - Add (not subtract) the bus offset when calculating DMA address
     (Wang Lu)

  ASPM:
   - Re-enable LTR at Downstream Ports so they don't report Unsupported
     Requests when reset or hot-added devices send LTR messages
     (Mingchuang Qiao)

  Apple PCIe controller driver:
   - Add driver for Apple M1 PCIe controller (Alyssa Rosenzweig, Marc
     Zyngier)

  Cadence PCIe controller driver:
   - Return success when probe succeeds instead of falling into error
     path (Li Chen)

  HiSilicon Kirin PCIe controller driver:
   - Reorganize PHY logic and add support for external PHY drivers
     (Mauro Carvalho Chehab)
   - Support PERST# GPIOs for HiKey970 external PEX 8606 bridge (Mauro
     Carvalho Chehab)
   - Add Kirin 970 support (Mauro Carvalho Chehab)
   - Make driver removable (Mauro Carvalho Chehab)

  Intel VMD host bridge driver:
   - If IOMMU supports interrupt remapping, leave VMD MSI-X remapping
     enabled (Adrian Huang)
   - Number each controller so we can tell them apart in
     /proc/interrupts (Chunguang Xu)
   - Avoid building on UML because VMD depends on x86 bare metal APIs
     (Johannes Berg)

  Marvell Aardvark PCIe controller driver:
   - Define macros for PCI_EXP_DEVCTL_PAYLOAD_* (Pali Rohár)
   - Set Max Payload Size to 512 bytes per Marvell spec (Pali Rohár)
   - Downgrade PIO Response Status messages to debug level (Marek Behún)
   - Preserve CRS SV (Config Request Retry Software Visibility) bit in
     emulated Root Control register (Pali Rohár)
   - Fix issue in configuring reference clock (Pali Rohár)
   - Don't clear status bits for masked interrupts (Pali Rohár)
   - Don't mask unused interrupts (Pali Rohár)
   - Avoid code repetition in advk_pcie_rd_conf() (Marek Behún)
   - Retry config accesses on CRS response (Pali Rohár)
   - Simplify emulated Root Capabilities initialization (Pali Rohár)
   - Fix several link training issues (Pali Rohár)
   - Fix link-up checking via LTSSM (Pali Rohár)
   - Fix reporting of Data Link Layer Link Active (Pali Rohár)
   - Fix emulation of W1C bits (Marek Behún)
   - Fix MSI domain .alloc() method to return zero on success (Marek
     Behún)
   - Read entire 16-bit MSI vector in MSI handler, not just low 8 bits
     (Marek Behún)
   - Clear Root Port I/O Space, Memory Space, and Bus Master Enable bits
     at startup; PCI core will set those as necessary (Pali Rohár)
   - When operating as a Root Port, set class code to "PCI Bridge"
     instead of the default "Mass Storage Controller" (Pali Rohár)
   - Add emulation for PCI_BRIDGE_CTL_BUS_RESET since aardvark doesn't
     implement this per spec (Pali Rohár)
   - Add emulation of option ROM BAR since aardvark doesn't implement
     this per spec (Pali Rohár)

  MediaTek MT7621 PCIe controller driver:
   - Add MediaTek MT7621 PCIe host controller driver and DT binding
     (Sergio Paracuellos)

  Qualcomm PCIe controller driver:
   - Add SC8180x compatible string (Bjorn Andersson)
   - Add endpoint controller driver and DT binding (Manivannan
     Sadhasivam)
   - Restructure to use of_device_get_match_data() (Prasad Malisetty)
   - Add SC7280-specific pcie_1_pipe_clk_src handling (Prasad Malisetty)

  Renesas R-Car PCIe controller driver:
   - Remove unnecessary includes (Geert Uytterhoeven)

  Rockchip DesignWare PCIe controller driver:
   - Add DT binding (Simon Xue)

  Socionext UniPhier Pro5 controller driver:
   - Serialize INTx masking/unmasking (Kunihiko Hayashi)

  Synopsys DesignWare PCIe controller driver:
   - Run dwc .host_init() method before registering MSI interrupt
     handler so we can deal with pending interrupts left by bootloader
     (Bjorn Andersson)
   - Clean up Kconfig dependencies (Andy Shevchenko)
   - Export symbols to allow more modular drivers (Luca Ceresoli)

  TI DRA7xx PCIe controller driver:
   - Allow host and endpoint drivers to be modules (Luca Ceresoli)
   - Enable external clock if present (Luca Ceresoli)

  TI J721E PCIe driver:
   - Disable PHY when probe fails after initializing it (Christophe
     JAILLET)

  MicroSemi Switchtec management driver:
   - Return error to application when command execution fails because an
     out-of-band reset has cleared the device BARs, Memory Space Enable,
     etc (Kelvin Cao)
   - Fix MRPC error status handling issue (Kelvin Cao)
   - Mask out other bits when reading of management VEP instance ID
     (Kelvin Cao)
   - Return EOPNOTSUPP instead of ENOTSUPP from sysfs show functions
     (Kelvin Cao)
   - Add check of event support (Logan Gunthorpe)

  Miscellaneous:
   - Remove unused pci_pool wrappers, which have been replaced by
     dma_pool (Cai Huoqing)
   - Use 'unsigned int' instead of bare 'unsigned' (Krzysztof
     Wilczyński)
   - Use kstrtobool() directly, sans strtobool() wrapper (Krzysztof
     Wilczyński)
   - Fix some sscanf(), sprintf() format mismatches (Krzysztof
     Wilczyński)
   - Update PCI subsystem information in MAINTAINERS (Krzysztof
     Wilczyński)
   - Correct some misspellings (Krzysztof Wilczyński)"

* tag 'pci-v5.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (137 commits)
  PCI: Add ACS quirk for Pericom PI7C9X2G switches
  PCI: apple: Configure RID to SID mapper on device addition
  iommu/dart: Exclude MSI doorbell from PCIe device IOVA range
  PCI: apple: Implement MSI support
  PCI: apple: Add INTx and per-port interrupt support
  PCI: kirin: Allow removing the driver
  PCI: kirin: De-init the dwc driver
  PCI: kirin: Disable clkreq during poweroff sequence
  PCI: kirin: Move the power-off code to a common routine
  PCI: kirin: Add power_off support for Kirin 960 PHY
  PCI: kirin: Allow building it as a module
  PCI: kirin: Add MODULE_* macros
  PCI: kirin: Add Kirin 970 compatible
  PCI: kirin: Support PERST# GPIOs for HiKey970 external PEX 8606 bridge
  PCI: apple: Set up reference clocks when probing
  PCI: apple: Add initial hardware bring-up
  PCI: of: Allow matching of an interrupt-map local to a PCI device
  of/irq: Allow matching of an interrupt-map local to an interrupt controller
  irqdomain: Make of_phandle_args_to_fwspec() generally available
  PCI: Do not enable AtomicOps on VFs
  ...

- Tidy setup-irq.c comments (Pranay Sanghai)

- Fix misspellings (Krzysztof Wilczyński)

- Fix sprintf(), sscanf() format mismatches (Krzysztof Wilczyński)

- Tidy cpqphp code formatting (Krzysztof Wilczyński)

- Remove unused pci_pool wrappers, which have been replaced by dma_pool
  (Cai Huoqing)

- Remove a redundant initialization in __pci_reset_function_locked() (Colin
  Ian King)

- Use 'unsigned int' instead of 'unsigned' (Krzysztof Wilczyński)

- Update PCI subsystem information in MAINTAINERS (Krzysztof Wilczyński)

- Include generic <linux/> headers instead of <asm/> for cpqphp and vmd
  (Krzysztof Wilczyński)

* pci/misc:
  PCI: vmd: Drop redundant includes of <asm/device.h>, <asm/msi.h>
  PCI: cpqphp: Use <linux/io.h> instead of <asm/io.h>
  MAINTAINERS: Update PCI subsystem information
  PCI: Prefer 'unsigned int' over bare 'unsigned'
  PCI: Remove redundant 'rc' initialization
  PCI: Remove unused pci_pool wrappers
  PCI: cpqphp: Format if-statement code block correctly
  PCI: Use unsigned to match sscanf("%x") in pci_dev_str_match_path()
  PCI: hv: Remove unnecessary use of %hx
  PCI: Correct misspelled and remove duplicated words
  PCI: Tidy comments

Use the preferred generic header file linux/io.h that already includes the
corresponding asm/io.h file.

Link: https://lore.kernel.org/r/20211013003145.1107148-2-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Derrick <jonathan.derrick@linux.dev>

Stuart Hayes reports that an error handled by DPC at a Root Port results
in pciehp gratuitously bringing down a subordinate hotplug port:

  RP -- UP -- DP -- UP -- DP (hotplug) -- EP

pciehp brings the slot down because the Link to the Endpoint goes down.
That is caused by a Hot Reset being propagated as a result of DPC.
Per PCIe Base Spec 5.0, section 6.6.1 "Conventional Reset":

  For a Switch, the following must cause a hot reset to be sent on all
  Downstream Ports: [...]

  * The Data Link Layer of the Upstream Port reporting DL_Down status.
    In Switches that support Link speeds greater than 5.0 GT/s, the
    Upstream Port must direct the LTSSM of each Downstream Port to the
    Hot Reset state, but not hold the LTSSMs in that state. This permits
    each Downstream Port to begin Link training immediately after its
    hot reset completes. This behavior is recommended for all Switches.

  * Receiving a hot reset on the Upstream Port.

Once DPC recovers, pcie_do_recovery() walks down the hierarchy and
invokes pcie_portdrv_slot_reset() to restore each port's config space.
At that point, a hotplug interrupt is signaled per PCIe Base Spec r5.0,
section 6.7.3.4 "Software Notification of Hot-Plug Events":

  If the Port is enabled for edge-triggered interrupt signaling using
  MSI or MSI-X, an interrupt message must be sent every time the logical
  AND of the following conditions transitions from FALSE to TRUE: [...]

  * The Hot-Plug Interrupt Enable bit in the Slot Control register is
    set to 1b.

  * At least one hot-plug event status bit in the Slot Status register
    and its associated enable bit in the Slot Control register are both
    set to 1b.

Prevent pciehp from gratuitously bringing down the slot by clearing the
error-induced Data Link Layer State Changed event before restoring
config space.  Afterwards, check whether the link has unexpectedly
failed to retrain and synthesize a DLLSC event if so.

Allow each pcie_port_service_driver (one of them being pciehp) to define
a slot_reset callback and re-use the existing pm_iter() function to
iterate over the callbacks.

Thereby, the Endpoint driver remains bound throughout error recovery and
may restore the device to working state.

Surprise removal during error recovery is detected through a Presence
Detect Changed event.  The hotplug port is expected to not signal that
event as a result of a Hot Reset.

The issue isn't DPC-specific, it also occurs when an error is handled by
AER through aer_root_reset().  So while the issue was noticed only now,
it's been around since 2006 when AER support was first introduced.

[bhelgaas: drop PCI_ERROR_RECOVERY Kconfig, split pm_iter() rename to
preparatory patch]
Link: https://lore.kernel.org/linux-pci/08c046b0-c9f2-3489-eeef-7e7aca435bb9@gmail.com/
Fixes: 6c2b374d7485 ("PCI-Express AER implemetation: AER core and aerdriver")
Link: https://lore.kernel.org/r/251f4edcc04c14f873ff1c967bc686169cd07d2d.1627638184.git.lukas@wunner.de
Reported-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Tested-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org # v2.6.19+: ba952824e6c1: PCI/portdrv: Report reset for frozen channel
Cc: Keith Busch <kbusch@kernel.org>

The code block related to the if-statement in cpqhp_set_irq() is
somewhat awkwardly formatted making the code hard to read.

Make it readable.  No change to functionality intended.

Link: https://lore.kernel.org/r/20211013011412.1110829-1-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Correct a number of misspelled words and remove any words that were
duplicated in the PCI tree.  No change to functionality intended.

Link: https://lore.kernel.org/r/20211006233827.147328-1-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Since commit 2a671f77ee49 ("s390/pci: fix use after free of zpci_dev")
the reference count of a zpci_dev is incremented between
pcibios_add_device() and pcibios_release_device() which was supposed to
prevent the zpci_dev from being freed while the common PCI code has
access to it. It was missed however that the handling of zPCI
availability events assumed that once zpci_zdev_put() was called no
later availability event would still see the device. With the previously
mentioned commit however this assumption no longer holds and we must
make sure that we only drop the initial long-lived reference the zPCI
subsystem holds exactly once.

Do so by introducing a zpci_device_reserved() function that handles when
a device is reserved. Here we make sure the zpci_dev will not be
considered for further events by removing it from the zpci_list.

This also means that the device actually stays in the
ZPCI_FN_STATE_RESERVED state between the time we know it has been
reserved and the final reference going away. We thus need to consider it
a real state instead of just a conceptual state after the removal. The
final cleanup of PCI resources, removal from zbus, and destruction of
the IOMMU stays in zpci_release_device() to make sure holders of the
reference do see valid data until the release.

Fixes: 2a671f77ee49 ("s390/pci: fix use after free of zpci_dev")
Cc: stable@vger.kernel.org
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

- Cache PCIe Device Capabilities register (Amey Narkhede)

- Add pcie_reset_flr() with 'probe' argument (Amey Narkhede)

- Add pdev->reset_methods[] array to track reset method ordering (Amey
  Narkhede)

- Remove reset_fn field from pci_dev (Amey Narkhede)

- Add sysfs interface to query and set device reset mechanism (Amey
  Narkhede)

- Add pci_set_acpi_fwnode() to set ACPI_COMPANION (Shanker Donthineni)

- Use acpi_pci_power_manageable() instead of duplicating logic (Shanker
  Donthineni)

- Set ACPI fwnode early and at the same time with OF (Shanker Donthineni)

- Add support for ACPI _RST reset method (Shanker Donthineni)

- Change reset function 'probe' argument to bool (Amey Narkhede)

* pci/reset:
  PCI: Change the type of probe argument in reset functions
  PCI: Add support for ACPI _RST reset method
  PCI: Setup ACPI fwnode early and at the same time with OF
  PCI: Use acpi_pci_power_manageable()
  PCI: Add pci_set_acpi_fwnode() to set ACPI_COMPANION
  PCI: Allow userspace to query and set device reset mechanism
  PCI: Remove reset_fn field from pci_dev
  PCI: Add array to track reset method ordering
  PCI: Add pcie_reset_flr() with 'probe' argument
  PCI: Cache PCIe Device Capabilities register

ebda_rsrc_controller() calls iounmap(io_mem) on the error path. Its caller,
ibmphp_access_ebda(), also calls iounmap(io_mem) on good and error paths.

Remove the iounmap(io_mem) invocation from ebda_rsrc_controller().

[bhelgaas: remove item from TODO]
Link: https://lore.kernel.org/r/20210818165751.591185-1-os.vaslot@gmail.com
Signed-off-by: Vishal Aslot <os.vaslot@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>