linux-kernel - [RESEND v13 15/25] CXL/PCI: Introduce PCI_ERS_RESULT

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Message-ID: <20251104170305.4163840-16-terry.bowman@amd.com>
Date: Tue, 4 Nov 2025 11:02:55 -0600
From: Terry Bowman <terry.bowman@....com>
To: <dave@...olabs.net>, <jonathan.cameron@...wei.com>,
	<dave.jiang@...el.com>, <alison.schofield@...el.com>,
	<dan.j.williams@...el.com>, <bhelgaas@...gle.com>, <shiju.jose@...wei.com>,
	<ming.li@...omail.com>, <Smita.KoralahalliChannabasappa@....com>,
	<rrichter@....com>, <dan.carpenter@...aro.org>,
	<PradeepVineshReddy.Kodamati@....com>, <lukas@...ner.de>,
	<Benjamin.Cheatham@....com>, <sathyanarayanan.kuppuswamy@...ux.intel.com>,
	<linux-cxl@...r.kernel.org>, <alucerop@....com>, <ira.weiny@...el.com>
CC: <linux-kernel@...r.kernel.org>, <linux-pci@...r.kernel.org>,
	<terry.bowman@....com>
Subject: [RESEND v13 15/25] CXL/PCI: Introduce PCI_ERS_RESULT_PANIC

The CXL driver's error handling for uncorrectable errors (UCE) will be
updated in the future. A required change is for the error handlers to
to force a system panic when a UCE is detected.

Introduce PCI_ERS_RESULT_PANIC as a 'enum pci_ers_result' type. This will
be used by CXL UCE fatal and non-fatal recovery in future patches. Update
PCIe recovery documentation with details of PCI_ERS_RESULT_PANIC.

Signed-off-by: Terry Bowman <terry.bowman@....com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
Reviewed-by: Ben Cheatham <benjamin.cheatham@....com>

---

Changes in  v12->v13:
- Add Dave Jiang's, Jonathan's, Ben's review-by
- Typo fix (Ben)

Changes v11 -> v12:
- Documentation requested (Lukas)
---
 Documentation/PCI/pci-error-recovery.rst | 6 ++++++
 include/linux/pci.h                      | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/Documentation/PCI/pci-error-recovery.rst b/Documentation/PCI/pci-error-recovery.rst
index 5df481ac6193..83505a585116 100644
--- a/Documentation/PCI/pci-error-recovery.rst
+++ b/Documentation/PCI/pci-error-recovery.rst
@@ -102,6 +102,8 @@ Possible return values are::
 		PCI_ERS_RESULT_NEED_RESET,  /* Device driver wants slot to be reset. */
 		PCI_ERS_RESULT_DISCONNECT,  /* Device has completely failed, is unrecoverable */
 		PCI_ERS_RESULT_RECOVERED,   /* Device driver is fully recovered and operational */
+		PCI_ERS_RESULT_NO_AER_DRIVER, /* No AER capabilities registered for the driver */
+		PCI_ERS_RESULT_PANIC,       /* System is unstable, panic. Is CXL specific */
 	};
 
 A driver does not have to implement all of these callbacks; however,
@@ -116,6 +118,10 @@ The actual steps taken by a platform to recover from a PCI error
 event will be platform-dependent, but will follow the general
 sequence described below.
 
+PCI_ERS_RESULT_PANIC is currently unique to CXL and handled in CXL
+cxl_do_recovery(). The PCI pcie_do_recovery() routine does not report or
+handle PCI_ERS_RESULT_PANIC.
+
 STEP 0: Error Event
 -------------------
 A PCI bus error is detected by the PCI hardware.  On powerpc, the slot
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 5c4759078d2f..cffa5535f28d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -890,6 +890,9 @@ enum pci_ers_result {
 
 	/* No AER capabilities registered for the driver */
 	PCI_ERS_RESULT_NO_AER_DRIVER = (__force pci_ers_result_t) 6,
+
+	/* System is unstable, panic. Is CXL specific */
+	PCI_ERS_RESULT_PANIC = (__force pci_ers_result_t) 7,
 };
 
 /* PCI bus error event callbacks */
-- 
2.34.1