[PATCH v8 02/20] PCI/DPC: Log Error Source ID only when valid

[Bjorn Helgaas]

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.

Fixes: 26e515713342 ("PCI: Add Downstream Port Containment driver")
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
Tested-by: Krzysztof Wilczyński <kwilczynski at kernel.org>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy at linux.intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron at huawei.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen at linux.intel.com>
Link: https://patch.msgid.link/20250520215047.1350603-3-helgaas@kernel.org
---
 drivers/pci/pcie/dpc.c | 64 ++++++++++++++++++++++++------------------
 1 file changed, 36 insertions(+), 28 deletions(-)

diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index 3daaf61c79c9..9d85f1b3b761 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -261,37 +261,45 @@ void dpc_process_error(struct pci_dev *pdev)
 	struct aer_err_info info = {};
 
 	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");
 
-	/* show RP PIO error detail information */
-	if (pdev->dpc_rp_extensions &&
-	    reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_IN_EXT &&
-	    ext_reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_RP_PIO)
-		dpc_process_rp_pio_error(pdev);
-	else if (reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_UNCOR &&
-		 dpc_get_aer_uncorrect_severity(pdev, &info) &&
-		 aer_get_device_error_info(pdev, &info)) {
-		aer_print_error(pdev, &info);
-		pci_aer_clear_nonfatal_status(pdev);
-		pci_aer_clear_fatal_status(pdev);
+	switch (reason) {
+	case PCI_EXP_DPC_STATUS_TRIGGER_RSN_UNCOR:
+		pci_warn(pdev, "containment event, status:%#06x: unmasked uncorrectable error detected\n",
+			 status);
+		if (dpc_get_aer_uncorrect_severity(pdev, &info) &&
+		    aer_get_device_error_info(pdev, &info)) {
+			aer_print_error(pdev, &info);
+			pci_aer_clear_nonfatal_status(pdev);
+			pci_aer_clear_fatal_status(pdev);
+		}
+		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));
+		break;
+	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");
+		/* show RP PIO error detail information */
+		if (ext_reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_RP_PIO &&
+		    pdev->dpc_rp_extensions)
+			dpc_process_rp_pio_error(pdev);
+		break;
 	}
 }
 
-- 
2.43.0