[PATCH v15 5/9] PCI: Establish common CXL Port protocol error flow

Terry Bowman
2026-02-03T02:54:01Z

Introduce CXL Port protocol error handling callbacks to unify detection,
logging, and recovery across CXL Ports and Endpoints, including RCH
downstream ports. Establish a consistent flow for correctable and
uncorrectable CXL protocol errors.

Provide the solution by adding cxl_port_cor_error_detected() and
cxl_port_error_detected() to handle correctable and uncorrectable handling
through CXL RAS helpers, coordinating uncorrectable recovery in
cxl_do_recovery(), and panicking when the handler returns PCI_ERS_RESULT_PANIC
to preserve fatal cachemem behavior. Gate endpoint handling on the endpoint
driver being bound to avoid processing errors on disabled devices.

Centralize the RAS base lookup in cxl_get_ras_base(), selecting the
downstream-port dport->regs.ras for Root/Downstream Ports and port->regs.ras
for Upstream Ports/Endpoints.

Export pcie_clear_device_status() and pci_aer_clear_fatal_status() to enable
cxl_core to clear PCIe/AER state in these flows.

Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Dave Jiang dave.jiang@intel.com

---

Changes in v14->v15:
- Update commit message and title. Added Bjorn's ack.
- Move CE and UCE handling logic here

Changes in v13->v14:
- Add Dave Jiang's review-by
- Update commit message & headline (Bjorn)
- Refactor cxl_port_error_detected()/cxl_port_cor_error_detected() to
one line (Jonathan)
- Remove cxl_walk_port() (Dan)
- Remove cxl_pci_drv_bound(). Check for 'is_cxl' parent port is
sufficient (Dan)
- Remove device_lock_if()
- Combined CE and UCE here (Terry)

Changes in v12->v13:
- Move get_pci_cxl_host_dev() and cxl_handle_proto_error() to Dequeue
patch (Terry)
- Remove EP case in cxl_get_ras_base(), not used. (Terry)
- Remove check for dport->dport_dev (Dave)
- Remove whitespace (Terry)

Changes in v11->v12:
- Add call to cxl_pci_drv_bound() in cxl_handle_proto_error() and
pci_to_cxl_dev()
- Change cxl_error_detected() -> cxl_cor_error_detected()
- Remove NULL variable assignments
- Replace bus_find_device() with find_cxl_port_by_uport() for upstream
port searches.

Changes in v10->v11:
- None
---
drivers/cxl/core/ras.c | 134 +++++++++++++++++++++++++++++++++++++++++
drivers/pci/pci.c | 1 +
drivers/pci/pci.h | 2 -
drivers/pci/pcie/aer.c | 1 +
include/linux/aer.h | 2 +
include/linux/pci.h | 2 +
6 files changed, 140 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
index a6c0bc6d7203..0216dafa6118 100644
--- a/drivers/cxl/core/ras.c
+++ b/drivers/cxl/core/ras.c
@@ -218,6 +218,68 @@ static struct cxl_port *get_cxl_port(struct pci_dev *pdev)
return NULL;
}

+static void __iomem *cxl_get_ras_base(struct device *dev)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+
+ switch (pci_pcie_type(pdev)) {
+ case PCI_EXP_TYPE_ROOT_PORT:
+ case PCI_EXP_TYPE_DOWNSTREAM:
+ {
+ struct cxl_dport *dport;
+ struct cxl_port *port __free(put_cxl_port) = find_cxl_port(&pdev->dev, &dport);
+
+ if (!dport) {
+ pci_err(pdev, "Failed to find the CXL device");
+ return NULL;
+ }
+ return dport->regs.ras;
+ }
+ case PCI_EXP_TYPE_UPSTREAM:
+ case PCI_EXP_TYPE_ENDPOINT:
+ {
+ struct cxl_port *port __free(put_cxl_port) = find_cxl_port_by_uport(&pdev->dev);
+
+ if (!port) {
+ pci_err(pdev, "Failed to find the CXL device");
+ return NULL;
+ }
+ return port->regs.ras;
+ }
+ }
+ dev_warn_once(dev, "Error: Unsupported device type (%#x)", pci_pcie_type(pdev));
+ return NULL;
+}
+
+static pci_ers_result_t cxl_port_error_detected(struct device *dev);
+
+static void cxl_do_recovery(struct pci_dev *pdev)
+{
+ struct cxl_port *port __free(put_cxl_port) = get_cxl_port(pdev);
+ pci_ers_result_t status;
+
+ if (!port) {
+ pci_err(pdev, "Failed to find the CXL device\n");
+ return;
+ }
+
+ status = cxl_port_error_detected(&pdev->dev);
+ if (status == PCI_ERS_RESULT_PANIC)
+ panic("CXL cachemem error.");
+
+ /*
+ * If we have native control of AER, clear error status in the device
+ * that detected the error. If the platform retained control of AER,
+ * it is responsible for clearing this status. In that case, the
+ * signaling device may not even be visible to the OS.
+ */
+ if (pcie_aer_is_native(pdev)) {
+ pcie_clear_device_status(pdev);
+ pci_aer_clear_nonfatal_status(pdev);
+ pci_aer_clear_fatal_status(pdev);
+ }
+}
+
void cxl_handle_cor_ras(struct device *dev, u64 serial, void __iomem *ras_base)
{
void __iomem *addr;
@@ -288,6 +350,60 @@ bool cxl_handle_ras(struct device *dev, u64 serial, void __iomem *ras_base)
return true;
}

+static void cxl_port_cor_error_detected(struct device *dev)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ struct cxl_port *port __free(put_cxl_port) = get_cxl_port(pdev);
+
+ if (is_cxl_endpoint(port)) {
+ struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
+ struct cxl_dev_state *cxlds = cxlmd->cxlds;
+
+ guard(device)(&cxlmd->dev);
+
+ if (!dev->driver) {
+ dev_warn(&pdev->dev,
+ "%s: memdev disabled, abort error handling\n",
+ dev_name(dev));
+ return;
+ }
+
+ if (cxlds->rcd)
+ cxl_handle_rdport_errors(cxlds);
+
+ cxl_handle_cor_ras(dev, cxlds->serial, cxl_get_ras_base(dev));
+ } else {
+ cxl_handle_cor_ras(dev, 0, cxl_get_ras_base(dev));
+ }
+}
+
+static pci_ers_result_t cxl_port_error_detected(struct device *dev)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ struct cxl_port *port __free(put_cxl_port) = get_cxl_port(pdev);
+
+ if (is_cxl_endpoint(port)) {
+ struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
+ struct cxl_dev_state *cxlds = cxlmd->cxlds;
+
+ guard(device)(&cxlmd->dev);
+
+ if (!dev->driver) {
+ dev_warn(&pdev->dev,
+ "%s: memdev disabled, abort error handling\n",
+ dev_name(dev));
+ return PCI_ERS_RESULT_NONE;
+ }
+
+ if (cxlds->rcd)
+ cxl_handle_rdport_errors(cxlds);
+
+ return cxl_handle_ras(dev, cxlds->serial, cxl_get_ras_base(dev));
+ } else {
+ return cxl_handle_ras(dev, 0, cxl_get_ras_base(dev));
+ }
+}
+
void cxl_cor_error_detected(struct pci_dev *pdev)
{
struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
@@ -363,6 +479,24 @@ EXPORT_SYMBOL_NS_GPL(cxl_error_detected, "CXL");

static void cxl_handle_proto_error(struct cxl_proto_err_work_data *err_info)
{
+ struct pci_dev *pdev = err_info->pdev;
+
+ if (err_info->severity == AER_CORRECTABLE) {
+
+ if (!pcie_aer_is_native(pdev))
+ return;
+
+ if (pdev->aer_cap)
+ pci_clear_and_set_config_dword(pdev,
+ pdev->aer_cap + PCI_ERR_COR_STATUS,
+ 0, PCI_ERR_COR_INTERNAL);
+
+ cxl_port_cor_error_detected(&pdev->dev);
+
+ pcie_clear_device_status(pdev);
+ } else {
+ cxl_do_recovery(pdev);
+ }
}

static void cxl_proto_err_work_fn(struct work_struct *work)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 13dbb405dc31..b7bfefdaf990 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2248,6 +2248,7 @@ void pcie_clear_device_status(struct pci_dev *dev)
pcie_capability_read_word(dev, PCI_EXP_DEVSTA, &sta);
pcie_capability_write_word(dev, PCI_EXP_DEVSTA, sta);
}
+EXPORT_SYMBOL_GPL(pcie_clear_device_status);
#endif

/**
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 8ccb3ba61e11..d81c4170f595 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -229,7 +229,6 @@ void pci_refresh_power_state(struct pci_dev *dev);
int pci_power_up(struct pci_dev *dev);
void pci_disable_enabled_device(struct pci_dev *dev);
int pci_finish_runtime_suspend(struct pci_dev *dev);
-void pcie_clear_device_status(struct pci_dev *dev);
void pcie_clear_root_pme_status(struct pci_dev *dev);
bool pci_check_pme_status(struct pci_dev *dev);
void pci_pme_wakeup_bus(struct pci_bus *bus);
@@ -1198,7 +1197,6 @@ void pci_restore_aer_state(struct pci_dev *dev);
static inline void pci_no_aer(void) { }
static inline void pci_aer_init(struct pci_dev *d) { }
static inline void pci_aer_exit(struct pci_dev *d) { }
-static inline void pci_aer_clear_fatal_status(struct pci_dev *dev) { }
static inline int pci_aer_clear_status(struct pci_dev *dev) { return -EINVAL; }
static inline int pci_aer_raw_clear_status(struct pci_dev *dev) { return -EINVAL; }
static inline void pci_save_aer_state(struct pci_dev *dev) { }
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 7af10a74da34..4fc9de4c78f8 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -298,6 +298,7 @@ void pci_aer_clear_fatal_status(struct pci_dev *dev)
if (status)
pci_write_config_dword(dev, aer + PCI_ERR_UNCOR_STATUS, status);
}
+EXPORT_SYMBOL_GPL(pci_aer_clear_fatal_status);

/**
* pci_aer_raw_clear_status - Clear AER error registers.
diff --git a/include/linux/aer.h b/include/linux/aer.h
index f351e41dd979..c1aef7859d0a 100644
--- a/include/linux/aer.h
+++ b/include/linux/aer.h
@@ -65,6 +65,7 @@ struct cxl_proto_err_work_data {

#if defined(CONFIG_PCIEAER)
int pci_aer_clear_nonfatal_status(struct pci_dev *dev);
+void pci_aer_clear_fatal_status(struct pci_dev *dev);
int pcie_aer_is_native(struct pci_dev *dev);
void pci_aer_unmask_internal_errors(struct pci_dev *dev);
#else
@@ -72,6 +73,7 @@ static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
{
return -EINVAL;
}
+static inline void pci_aer_clear_fatal_status(struct pci_dev *dev) { }
static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
static inline void pci_aer_unmask_internal_errors(struct pci_dev *dev) { }
#endif
diff --git a/include/linux/pci.h b/include/linux/pci.h
index ee05d5925b13..1ef4743bf151 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1921,8 +1921,10 @@ static inline void pci_hp_unignore_link_change(struct pci_dev *pdev) { }

#ifdef CONFIG_PCIEAER
bool pci_aer_available(void);
+void pcie_clear_device_status(struct pci_dev *dev);
#else
static inline bool pci_aer_available(void) { return false; }
+static inline void pcie_clear_device_status(struct pci_dev *dev) { }
#endif

bool pci_ats_disabled(void);
--
2.34.1