[PATCH v8 03/16] CXL/AER: Introduce Kfifo for forwarding CXL errors

[Terry Bowman]

CXL error handling will soon be moved from the AER driver into the CXL
driver. This requires a notification mechanism for the AER driver to share
the AER interrupt details with CXL driver. The notification is required for
the CXL drivers to then handle CXL RAS errors.

Add a kfifo work queue to be used by the AER driver and CXL driver. The AER
driver will be the sole kfifo producer adding work. The cxl_core will be
the sole kfifo consumer removing work. Add the boilerplate kfifo support.

Add CXL work queue handler registration functions in the AER driver. Export
the functions allowing CXL driver to access. Implement the registration
functions for the CXL driver to assign or clear the work handler function.

Create a work queue handler function, cxl_prot_err_work_fn(), as a stub for
now. The CXL specific handling will be added in future patch.

Introduce 'struct cxl_prot_err_info'. This structure caches CXL error
details used in completing error handling. This avoid duplicating some
function calls and allows the error to be treated generically when
possible.

Signed-off-by: Terry Bowman <terry.bowman@xxxxxxx>
---
 drivers/cxl/core/ras.c | 54 +++++++++++++++++++++++++++++++++++++++++-
 drivers/cxl/cxlpci.h   |  3 +++
 drivers/pci/pcie/aer.c | 39 ++++++++++++++++++++++++++++++
 include/linux/aer.h    | 37 +++++++++++++++++++++++++++++
 4 files changed, 132 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
index 485a831695c7..ecb60a5962de 100644
--- a/drivers/cxl/core/ras.c
+++ b/drivers/cxl/core/ras.c
@@ -5,6 +5,7 @@
 #include <linux/aer.h>
 #include <cxl/event.h>
 #include <cxlmem.h>
+#include <cxlpci.h>
 #include "trace.h"
 
 static void cxl_cper_trace_corr_port_prot_err(struct pci_dev *pdev,
@@ -107,13 +108,64 @@ static void cxl_cper_prot_err_work_fn(struct work_struct *work)
 }
 static DECLARE_WORK(cxl_cper_prot_err_work, cxl_cper_prot_err_work_fn);
 
+int cxl_create_prot_err_info(struct pci_dev *_pdev, int severity,
+			     struct cxl_prot_error_info *err_info)
+{
+	struct pci_dev *pdev __free(pci_dev_put) = pci_dev_get(_pdev);
+	struct cxl_dev_state *cxlds;
+
+	if (!pdev || !err_info) {
+		pr_warn_once("Error: parameter is NULL");
+		return -ENODEV;
+	}
+
+	if ((pci_pcie_type(pdev) != PCI_EXP_TYPE_ENDPOINT) &&
+	    (pci_pcie_type(pdev) != PCI_EXP_TYPE_RC_END)) {
+		pci_warn_once(pdev, "Error: Unsupported device type (%X)", pci_pcie_type(pdev));
+		return -ENODEV;
+	}
+
+	cxlds = pci_get_drvdata(pdev);
+	struct device *dev __free(put_device) = get_device(&cxlds->cxlmd->dev);
+
+	if (!dev)
+		return -ENODEV;
+
+	*err_info = (struct cxl_prot_error_info){ 0 };
+	err_info->ras_base = cxlds->regs.ras;
+	err_info->severity = severity;
+	err_info->pdev = pdev;
+	err_info->dev = dev;
+
+	return 0;
+}
+
+struct work_struct cxl_prot_err_work;
+
 int cxl_ras_init(void)
 {
-	return cxl_cper_register_prot_err_work(&cxl_cper_prot_err_work);
+	int rc;
+
+	rc = cxl_cper_register_prot_err_work(&cxl_cper_prot_err_work);
+	if (rc) {
+		pr_err("Failed to register CPER kfifo with AER driver");
+		return rc;
+	}
+
+	rc = cxl_register_prot_err_work(&cxl_prot_err_work, cxl_create_prot_err_info);
+	if (rc) {
+		pr_err("Failed to register kfifo with AER driver");
+		return rc;
+	}
+
+	return rc;
 }
 
 void cxl_ras_exit(void)
 {
 	cxl_cper_unregister_prot_err_work(&cxl_cper_prot_err_work);
 	cancel_work_sync(&cxl_cper_prot_err_work);
+
+	cxl_unregister_prot_err_work();
+	cancel_work_sync(&cxl_prot_err_work);
 }
diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
index 54e219b0049e..92d72c0423ab 100644
--- a/drivers/cxl/cxlpci.h
+++ b/drivers/cxl/cxlpci.h
@@ -4,6 +4,7 @@
 #define __CXL_PCI_H__
 #include <linux/pci.h>
 #include "cxl.h"
+#include "linux/aer.h"
 
 #define CXL_MEMORY_PROGIF	0x10
 
@@ -135,4 +136,6 @@ void read_cdat_data(struct cxl_port *port);
 void cxl_cor_error_detected(struct pci_dev *pdev);
 pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
 				    pci_channel_state_t state);
+int cxl_create_prot_err_info(struct pci_dev *_pdev, int severity,
+			     struct cxl_prot_error_info *err_info);
 #endif /* __CXL_PCI_H__ */
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 83f2069f111e..46123b70f496 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -110,6 +110,16 @@ struct aer_stats {
 static int pcie_aer_disable;
 static pci_ers_result_t aer_root_reset(struct pci_dev *dev);
 
+#if defined(CONFIG_PCIEAER_CXL)
+#define CXL_ERROR_SOURCES_MAX          128
+static DEFINE_KFIFO(cxl_prot_err_fifo, struct cxl_prot_err_work_data,
+		    CXL_ERROR_SOURCES_MAX);
+static DEFINE_SPINLOCK(cxl_prot_err_fifo_lock);
+struct work_struct *cxl_prot_err_work;
+static int (*cxl_create_prot_err_info)(struct pci_dev*, int severity,
+				       struct cxl_prot_error_info*);
+#endif
+
 void pci_no_aer(void)
 {
 	pcie_aer_disable = 1;
@@ -1577,6 +1587,35 @@ static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
 	return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_RECOVERED;
 }
 
+
+#if defined(CONFIG_PCIEAER_CXL)
+int cxl_register_prot_err_work(struct work_struct *work,
+			       int (*_cxl_create_prot_err_info)(struct pci_dev*, int,
+								struct cxl_prot_error_info*))
+{
+	guard(spinlock)(&cxl_prot_err_fifo_lock);
+	cxl_prot_err_work = work;
+	cxl_create_prot_err_info = _cxl_create_prot_err_info;
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_register_prot_err_work, "CXL");
+
+int cxl_unregister_prot_err_work(void)
+{
+	guard(spinlock)(&cxl_prot_err_fifo_lock);
+	cxl_prot_err_work = NULL;
+	cxl_create_prot_err_info = NULL;
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_unregister_prot_err_work, "CXL");
+
+int cxl_prot_err_kfifo_get(struct cxl_prot_err_work_data *wd)
+{
+	return kfifo_get(&cxl_prot_err_fifo, wd);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_prot_err_kfifo_get, "CXL");
+#endif
+
 static struct pcie_port_service_driver aerdriver = {
 	.name		= "aer",
 	.port_type	= PCIE_ANY_PORT,
diff --git a/include/linux/aer.h b/include/linux/aer.h
index 947b63091902..761d6f5cd792 100644
--- a/include/linux/aer.h
+++ b/include/linux/aer.h
@@ -10,6 +10,7 @@
 
 #include <linux/errno.h>
 #include <linux/types.h>
+#include <linux/workqueue_types.h>
 
 #define AER_NONFATAL			0
 #define AER_FATAL			1
@@ -45,6 +46,24 @@ struct aer_capability_regs {
 	u16 uncor_err_source;
 };
 
+/**
+ * struct cxl_prot_err_info - Error information used in CXL error handling
+ * @pdev: PCI device with CXL error
+ * @dev: CXL device with error. From CXL topology using ACPI/platform discovery
+ * @ras_base: Mapped address of CXL RAS registers
+ * @severity: CXL AER/RAS severity: AER_CORRECTABLE, AER_FATAL, AER_NONFATAL
+ */
+struct cxl_prot_error_info {
+	struct pci_dev *pdev;
+	struct device *dev;
+	void __iomem *ras_base;
+	int severity;
+};
+
+struct cxl_prot_err_work_data {
+	struct cxl_prot_error_info err_info;
+};
+
 #if defined(CONFIG_PCIEAER)
 int pci_aer_clear_nonfatal_status(struct pci_dev *dev);
 int pcie_aer_is_native(struct pci_dev *dev);
@@ -56,6 +75,24 @@ static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
 static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
 #endif
 
+#if defined(CONFIG_PCIEAER_CXL)
+int cxl_register_prot_err_work(struct work_struct *work,
+			       int (*_cxl_create_proto_err_info)(struct pci_dev*, int,
+								 struct cxl_prot_error_info*));
+int cxl_unregister_prot_err_work(void);
+int cxl_prot_err_kfifo_get(struct cxl_prot_err_work_data *wd);
+#else
+static inline int
+cxl_register_prot_err_work(struct work_struct *work,
+			   int (*_cxl_create_proto_err_info)(struct pci_dev*, int,
+							     struct cxl_prot_error_info*))
+{
+	return 0;
+}
+static inline int cxl_unregister_prot_err_work(void) { return 0; }
+static inline int cxl_prot_err_kfifo_get(struct cxl_prot_err_work_data *wd) { return 0; }
+#endif
+
 void pci_print_aer(struct pci_dev *dev, int aer_severity,
 		    struct aer_capability_regs *aer);
 int cper_severity_to_aer(int cper_severity);
-- 
2.34.1