Re: [Bug 215525] New: HotPlug does not work on upstream kernel 5.17.0-rc1

[Lukas Wunner <lukas@wunner.de>]

On Mon, Jan 24, 2022 at 03:46:35PM -0600, Bjorn Helgaas wrote:
> On Mon, Jan 24, 2022 at 11:46:14AM +0000, bugzilla-daemon@bugzilla.kernel.org wrote:
> > https://bugzilla.kernel.org/show_bug.cgi?id=215525
> > 
> > While testing on latest upstream kernel we noticed that with the
> > merge commit d0a231f01e5b hotplug and hotunplug of nvme drives
> > stopped working.
[...]
> Only three commits touch pciehp:
> 
>   085a9f43433f ("PCI: pciehp: Use down_read/write_nested(reset_lock) to fix lockdep errors")
>   23584c1ed3e1 ("PCI: pciehp: Fix infinite loop in IRQ handler upon power fault")
>   a3b0f10db148 ("PCI: pciehp: Use PCI_POSSIBLE_ERROR() to check config reads")

Those commits pertain to *native* hotplug, however the machine in question
does not grant hotplug control to OSPM, so pciehp isn't even probed for
any ports on that machine:

  acpi PNP0A08:09: _OSC: OS supports [ASPM ClockPM Segments MSI HPX-Type3]
  acpi PNP0A08:09: _OSC: not requesting OS control; OS requires [ExtendedConfig ASPM ClockPM MSI]

Are these ports supposed to be handled by native hotplug or acpiphp?
Perhaps CONFIG_HOTPLUG_PCI_PCIE was erroneously not enabled?

It's unfortunate that the bugzilla only contains the dmesg dump of
broken hotplug, but not of working hotplug.  That would make it easier
to determine what's going wrong.

Thanks,

Lukas