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

Bjorn Helgaas
2025-05-20T14:05:36Z

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!