ACPI: APEI: GHES: Add helper to copy CPER CXL protocol error info to work struct

Make a helper out of cxl_cper_post_prot_err() that checks the CXL agent
type and copy the CPER CXL protocol errors information to a work data
structure.

Export the new symbol for reuse by ELOG.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com>
[ rjw: Subject tweak ]
Link: https://patch.msgid.link/20260114101543.85926-5-fabio.m.de.francesco@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: fdefranc

drivers/acpi/apei/ghes.c

@@ -739,7 +739,6 @@ static void cxl_cper_post_prot_err(struct cxl_cper_sec_prot_err *prot_err,
 {
 #ifdef CONFIG_ACPI_APEI_PCIEAER
 	struct cxl_cper_prot_err_work_data wd;
-	u8 *dvsec_start, *cap_start;
 
 	if (cxl_cper_sec_prot_err_valid(prot_err))
 		return;
@@ -749,27 +748,8 @@ static void cxl_cper_post_prot_err(struct cxl_cper_sec_prot_err *prot_err,
 	if (!cxl_cper_prot_err_work)
 		return;
 
-	switch (prot_err->agent_type) {
-	case RCD:
-	case DEVICE:
-	case LD:
-	case FMLD:
-	case RP:
-	case DSP:
-	case USP:
-		memcpy(&wd.prot_err, prot_err, sizeof(wd.prot_err));
-
-		dvsec_start = (u8 *)(prot_err + 1);
-		cap_start = dvsec_start + prot_err->dvsec_len;
-
-		memcpy(&wd.ras_cap, cap_start, sizeof(wd.ras_cap));
-		wd.severity = cper_severity_to_aer(severity);
-		break;
-	default:
-		pr_err_ratelimited("CXL CPER invalid agent type: %d\n",
-				   prot_err->agent_type);
+	if (cxl_cper_setup_prot_err_work_data(&wd, prot_err, severity))
 		return;
-	}
 
 	if (!kfifo_put(&cxl_cper_prot_err_fifo, wd)) {
 		pr_err_ratelimited("CXL CPER kfifo overflow\n");

drivers/acpi/apei/ghes_helpers.c

@@ -2,6 +2,7 @@
 // Copyright(c) 2025 Intel Corporation. All rights reserved
 
 #include <linux/printk.h>
+#include <linux/aer.h>
 #include <cxl/event.h>
 
 int cxl_cper_sec_prot_err_valid(struct cxl_cper_sec_prot_err *prot_err)
@@ -31,3 +32,35 @@ int cxl_cper_sec_prot_err_valid(struct cxl_cper_sec_prot_err *prot_err)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(cxl_cper_sec_prot_err_valid);
+
+int cxl_cper_setup_prot_err_work_data(struct cxl_cper_prot_err_work_data *wd,
+				      struct cxl_cper_sec_prot_err *prot_err,
+				      int severity)
+{
+	u8 *dvsec_start, *cap_start;
+
+	switch (prot_err->agent_type) {
+	case RCD:
+	case DEVICE:
+	case LD:
+	case FMLD:
+	case RP:
+	case DSP:
+	case USP:
+		memcpy(&wd->prot_err, prot_err, sizeof(wd->prot_err));
+
+		dvsec_start = (u8 *)(prot_err + 1);
+		cap_start = dvsec_start + prot_err->dvsec_len;
+
+		memcpy(&wd->ras_cap, cap_start, sizeof(wd->ras_cap));
+		wd->severity = cper_severity_to_aer(severity);
+		break;
+	default:
+		pr_err_ratelimited("CXL CPER invalid agent type: %d\n",
+				   prot_err->agent_type);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cxl_cper_setup_prot_err_work_data);

include/cxl/event.h

@@ -322,12 +322,22 @@ static inline int cxl_cper_prot_err_kfifo_get(struct cxl_cper_prot_err_work_data
 
 #ifdef CONFIG_ACPI_APEI_PCIEAER
 int cxl_cper_sec_prot_err_valid(struct cxl_cper_sec_prot_err *prot_err);
+int cxl_cper_setup_prot_err_work_data(struct cxl_cper_prot_err_work_data *wd,
+				      struct cxl_cper_sec_prot_err *prot_err,
+				      int severity);
 #else
 static inline int
 cxl_cper_sec_prot_err_valid(struct cxl_cper_sec_prot_err *prot_err)
 {
 	return -EOPNOTSUPP;
 }
+static inline int
+cxl_cper_setup_prot_err_work_data(struct cxl_cper_prot_err_work_data *wd,
+				  struct cxl_cper_sec_prot_err *prot_err,
+				  int severity)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 
 #endif /* _LINUX_CXL_EVENT_H */