Re: [PATCH v6 02/16] PCI/DPC: Log Error Source ID only when valid

Ilpo Järvinen
2025-05-20T14:20:46Z

On Tue, 20 May 2025, Bjorn Helgaas wrote:

> On Mon, May 19, 2025 at 04:15:56PM -0700, Sathyanarayanan Kuppuswamy wrote:
> > On 5/19/25 2:35 PM, Bjorn Helgaas wrote:
> > > From: Bjorn Helgaas <bhelgaas@google.com>
> > >
> > > DPC Error Source ID is only valid when the DPC Trigger Reason indicates
> > > that DPC was triggered due to reception of an ERR_NONFATAL or ERR_FATAL
> > > Message (PCIe r6.0, sec 7.9.14.5).
> > >
> > > When DPC was triggered by ERR_NONFATAL (PCI_EXP_DPC_STATUS_TRIGGER_RSN_NFE)
> > > or ERR_FATAL (PCI_EXP_DPC_STATUS_TRIGGER_RSN_FE) from a downstream device,
> > > log the Error Source ID (decoded into domain/bus/device/function). Don't
> > > print the source otherwise, since it's not valid.
> > >
> > > For DPC trigger due to reception of ERR_NONFATAL or ERR_FATAL, the dmesg
> > > logging changes:
> > >
> > > - pci 0000:00:01.0: DPC: containment event, status:0x000d source:0x0200
> > > - pci 0000:00:01.0: DPC: ERR_FATAL detected
> > > + pci 0000:00:01.0: DPC: containment event, status:0x000d, ERR_FATAL received from 0000:02:00.0
> > >
> > > and when DPC triggered for other reasons, where DPC Error Source ID is
> > > undefined, e.g., unmasked uncorrectable error:
> > >
> > > - pci 0000:00:01.0: DPC: containment event, status:0x0009 source:0x0200
> > > - pci 0000:00:01.0: DPC: unmasked uncorrectable error detected
> > > + pci 0000:00:01.0: DPC: containment event, status:0x0009: unmasked uncorrectable error detected
> > >
> > > Previously the "containment event" message was at KERN_INFO and the
> > > "%s detected" message was at KERN_WARNING. Now the single message is at
> > > KERN_WARNING.
> >
> > Since we are handling Uncorrectable errors, why not use pci_err?
>
> Sounds reasonable to me. I would do it in a separate patch because
> the point of this one is to avoid logging junk when Error Source ID is
> not valid.
>
> > > + pci_warn(pdev, "containment event, status:%#06x, %s received from %04x:%02x:%02x.%d\n",
> > > + status,
> >
> > I see the BDF extraction and format code in many places in the PCI
> > drivers. May be a common macro will make it more readable.
>
> Good idea. Not sure how to implement it, so I put that on my TODO
> list for now.

Instead of macros, it might be worth adding a printf specifier for this.
Together with some flags, it should be possible to cover also the
variations that print less than the full BDF format.

> > > + (reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_FE) ?
> > > + "ERR_FATAL" : "ERR_NONFATAL",
> > > + pci_domain_nr(pdev->bus), PCI_BUS_NUM(source),
> > > + PCI_SLOT(source), PCI_FUNC(source));
>

--
i.