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

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, May 20, 2025 at 01:28:02PM +0300, Ilpo Järvinen wrote:
> On Mon, 19 May 2025, Bjorn Helgaas wrote:
> > 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.
> > 
> > Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> > ---
> >  drivers/pci/pcie/dpc.c | 45 ++++++++++++++++++++++++++----------------
> >  1 file changed, 28 insertions(+), 17 deletions(-)
> > 
> > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> > index fe7719238456..315bf2bfd570 100644
> > --- a/drivers/pci/pcie/dpc.c
> > +++ b/drivers/pci/pcie/dpc.c
> > @@ -261,25 +261,36 @@ void dpc_process_error(struct pci_dev *pdev)
> >  	struct aer_err_info info = { 0 };
> >  
> >  	pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
> > -	pci_read_config_word(pdev, cap + PCI_EXP_DPC_SOURCE_ID, &source);
> > -
> > -	pci_info(pdev, "containment event, status:%#06x source:%#06x\n",
> > -		 status, source);
> >  
> >  	reason = status & PCI_EXP_DPC_STATUS_TRIGGER_RSN;
> > -	ext_reason = status & PCI_EXP_DPC_STATUS_TRIGGER_RSN_EXT;
> > -	pci_warn(pdev, "%s detected\n",
> > -		 (reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_UNCOR) ?
> > -		 "unmasked uncorrectable error" :
> > -		 (reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_NFE) ?
> > -		 "ERR_NONFATAL" :
> > -		 (reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_FE) ?
> > -		 "ERR_FATAL" :
> > -		 (ext_reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_RP_PIO) ?
> > -		 "RP PIO error" :
> > -		 (ext_reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_SW_TRIGGER) ?
> > -		 "software trigger" :
> > -		 "reserved error");
> > +
> > +	switch (reason) {
> > +	case PCI_EXP_DPC_STATUS_TRIGGER_RSN_UNCOR:
> > +		pci_warn(pdev, "containment event, status:%#06x: unmasked uncorrectable error detected\n",
> > +			 status);
> > +		break;
> > +	case PCI_EXP_DPC_STATUS_TRIGGER_RSN_NFE:
> > +	case PCI_EXP_DPC_STATUS_TRIGGER_RSN_FE:
> > +		pci_read_config_word(pdev, cap + PCI_EXP_DPC_SOURCE_ID,
> > +				     &source);
> > +		pci_warn(pdev, "containment event, status:%#06x, %s received from %04x:%02x:%02x.%d\n",
> > +			 status,
> > +			 (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));
> > +		return;
> > +	case PCI_EXP_DPC_STATUS_TRIGGER_RSN_IN_EXT:
> > +		ext_reason = status & PCI_EXP_DPC_STATUS_TRIGGER_RSN_EXT;
> > +		pci_warn(pdev, "containment event, status:%#06x: %s detected\n",
> > +			 status,
> > +			 (ext_reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_RP_PIO) ?
> > +			 "RP PIO error" :
> > +			 (ext_reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_SW_TRIGGER) ?
> > +			 "software trigger" :
> > +			 "reserved error");
> > +		break;
> > +	}
> >  
> >  	/* show RP PIO error detail information */
> >  	if (pdev->dpc_rp_extensions &&
> 
> After adding that switch (reason) there, wouldn't it make sense to move 
> also the code from the if blocks into the case blocks? That if 
> conditions check for reason anyway so those if branches would naturally 
> belong under one of the cases each.

Great idea, thanks!