Re: [PATCH] PCI: vmd: Enable Hotplug based on BIOS setting on VMD rootports

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc Grant, Rajat, Rajat]

On Wed, Dec 06, 2023 at 10:18:56AM +0800, Kai-Heng Feng wrote:
> On Wed, Nov 15, 2023 at 5:00 AM Nirmal Patel <nirmal.patel@linux.intel.com> wrote:
> > On Wed, 2023-11-08 at 16:49 +0200, Kai-Heng Feng wrote:
> > > On Wed, Nov 8, 2023 at 12:30 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
> ...

> > > > I assume you mean to revert 04b12ef163d1 ("PCI: vmd: Honor
> > > > ACPI _OSC on PCIe features").  That appeared in v5.17, and it
> > > > fixed (or at least prevented) an AER message flood.  We can't
> > > > simply revert 04b12ef163d1 unless we first prevent that AER
> > > > message flood in another way.
> > >
> > > The error is "correctable".  Does masking all correctable AER
> > > error by default make any sense? And add a sysfs knob to make it
> > > optional.
> >
> > I assume sysfs knob requires driver reload. right? Can you send a
> > patch?
> 
> What I mean is to mask Correctable Errors by default on *all*
> rootports, and create a new sysfs knob to let user decide if
> Correctable Errors should be unmasked.

I don't think we should mask Correctable Errors by default.  Even
though they've been corrected by hardware and no software action is
required, I think these errors are valuable signals about Link
integrity.

I think rate-limiting and/or reporting on the *frequency* of
Correctable Errors would make a lot of sense.  We had some work toward
this recently, but it hasn't quite gotten finished yet.

The most recent work I'm aware of is this:
https://lore.kernel.org/r/20230606035442.2886343-1-grundler@chromium.org

Bjorn