Re: [PATCH v15 0/4] Simplify PCIe native ownership

[Kuppuswamy Sathyanarayanan]

Hi Bjorn,

On 10/6/2026 10:51 AM, Bjorn Helgaas wrote:
> On Fri, Oct 02, 2026 at 02:18:24PM -0700, Kuppuswamy Sathyanarayanan wrote:
>> This revives Bjorn's v12 from November 2020, rebased onto v7.3-rc3.
>>
>>   https://lore.kernel.org/all/20201126011816.711106-1-helgaas@xxxxxxxxxx/
>>
>> The goal is unchanged.  Decide who owns each PCIe port service in one
>> place, when we interpret the _OSC results in acpi_pci_root_create(), so
>> that everywhere else only has to look at host_bridge->native_X.  For AER
>> specifically, host_bridge->native_aer becomes the single answer to the
>> question "may Linux touch the AER Capability?".  Today callers each have
>> to remember to also test pcie_ports_native and pci_aer_available().
>>
>> I posted v11.  Bjorn took it over at v12, split the _OSC changes in two
>> and deferred the "pcie_ports=dpc-native" work.  The v12 review comments
>> were agreed but never respun, and the series stalled.  v13 was that
>> respin.
>>
>>   https://lore.kernel.org/r/cover.1603766889.git.sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx [v11]
>>
>> Bjorn suggested reviving it in response to Guixin Liu's report that
>> "pcie_ports=native" no longer enables DPC.  The DPC service binds on
>> host_bridge->native_aer, and that flag did not reflect the command line,
>> so DPC stayed off when firmware retained AER control.  Patch 3 fixes it
>> by making the flag reflect it.
>>
>>   https://lore.kernel.org/linux-pci/20260901064554.2178688-1-kanie@xxxxxxxxxxxxxxxxx/
>>
>> Patch 3 has a side effect worth calling out.  drivers/cxl/core/ras.c did
>> not exist in 2020 and tests host_bridge->native_aer with no
>> pcie_ports_native fallback, so it has been quietly ignoring
>> "pcie_ports=native".  Centralizing the check fixes that.
>>
>> Binding the DPC service on host_bridge->native_dpc, rather than on
>> native_aer, is left for a separate patch on top of Lukas's series that
>> removes the DPC/AER dependency, as agreed with Bjorn.  That change
>> alters behavior, so it does not belong in this cleanup.
>>
>>   https://lore.kernel.org/r/cover.1790531238.git.lukas@xxxxxxxxx
>>   https://lore.kernel.org/r/20261001221408.GA2731929@bhelgaas
>>
>> Changes since v14:
>>   * Patch 3: fold "pcie_ports=dpc-native" into the _OSC control mask as
>>     well, so host_bridge->native_dpc and the "OS native features" line
>>     reflect it (Bjorn).
>>   * Picked up Guixin's Reviewed-by on patch 3.
>>
>> v14 posting
>> https://lore.kernel.org/r/20260922204548.3884906-1-sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx
>>
>> Changes since v13:
>>   * Lukas suggested dropping AER cap check fix (patch 1 of v13). He has
>>     a series underway to fix it cleanly (removing DPC/AER dependency).
>>     So dropped the patch as suggested.
>>     https://lore.kernel.org/r/aq95LGUHL-pnmTlr@xxxxxxxxx
>>   * Addressed use of IS_ENABLED(CONFIG_PCIEPORTBUS) instead of #ifdef
>>     (Lukas).
>>   * Added Fixes tag in patch 3 (Guixin Liu).
>>   * Added Acks from Rafael.
>>
>> v13 posting
>> https://lore.kernel.org/r/20260919162655.3499010-1-sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx
>>
>> Bjorn Helgaas (1):
>>   PCI: Centralize pci_aer_available() checking
>>
>> Kuppuswamy Sathyanarayanan (3):
>>   PCI: Assume control of portdrv-related features only when portdrv
>>     enabled
>>   PCI/ACPI: Tidy _OSC control bit checking
>>   PCI/ACPI: Centralize pcie_ports_native checking
>>
>>  drivers/acpi/pci_root.c           | 78 +++++++++++++++++++++++++------
>>  drivers/pci/hotplug/pciehp_core.c |  2 +-
>>  drivers/pci/pci-acpi.c            |  3 --
>>  drivers/pci/pcie/aer.c            |  6 +--
>>  drivers/pci/pcie/aer_cxl_rch.c    |  2 +-
>>  drivers/pci/pcie/err.c            |  2 +-
>>  drivers/pci/pcie/portdrv.c        |  7 ++-
>>  drivers/pci/pcie/portdrv.h        |  2 -
>>  drivers/pci/probe.c               | 10 ++--
>>  include/linux/pci.h               |  2 +
>>  10 files changed, 80 insertions(+), 34 deletions(-)
> 
> I put the first three patches on pci/portdrv for v7.4, thanks!
> 
> I deferred the last ("PCI: Centralize pci_aer_available() checking")
> while we sort out the MSI/AER question, but I want to make sure we get
> the rest in v7.4.

Thanks for picking it up.
-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer