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

[Bjorn Helgaas]

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 at 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.

> > +			 (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));