Move the CPER CXL protocol errors validity check out of
cxl_cper_post_prot_err() to new cxl_cper_sec_prot_err_valid() and limit
the serial number check only to CXL agents that are CXL devices (UEFI
v2.10, Appendix N.2.13).

Export the new symbol for reuse by ELOG.

Signed-off-by: Fabio M. De Francesco <redacted>
---
  drivers/acpi/apei/ghes.c | 32 ++++++++++++++++++++++----------
  include/cxl/event.h      | 10 ++++++++++
  2 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index d6fe5f020e96..e69ae864f43d 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c

@@ -706,30 +706,42 @@ static DEFINE_KFIFO(cxl_cper_prot_err_fifo, struct cxl_cper_prot_err_work_data,
  static DEFINE_SPINLOCK(cxl_cper_prot_err_work_lock);
  struct work_struct *cxl_cper_prot_err_work;
  
-static void cxl_cper_post_prot_err(struct cxl_cper_sec_prot_err *prot_err,
-				   int severity)
+int cxl_cper_sec_prot_err_valid(struct cxl_cper_sec_prot_err *prot_err)
  {
-	struct cxl_cper_prot_err_work_data wd;
-	u8 *dvsec_start, *cap_start;
-
  	if (!(prot_err->valid_bits & PROT_ERR_VALID_AGENT_ADDRESS)) {
  		pr_err_ratelimited("CXL CPER invalid agent type\n");
-		return;
+		return -EINVAL;
  	}
  
  	if (!(prot_err->valid_bits & PROT_ERR_VALID_ERROR_LOG)) {
  		pr_err_ratelimited("CXL CPER invalid protocol error log\n");
-		return;
+		return -EINVAL;
  	}
  
  	if (prot_err->err_len != sizeof(struct cxl_ras_capability_regs)) {
  		pr_err_ratelimited("CXL CPER invalid RAS Cap size (%u)\n",
  				   prot_err->err_len);
-		return;
+		return -EINVAL;
  	}
  
-	if (!(prot_err->valid_bits & PROT_ERR_VALID_SERIAL_NUMBER))
-		pr_warn(FW_WARN "CXL CPER no device serial number\n");
+	if ((prot_err->agent_type == RCD || prot_err->agent_type == DEVICE ||
+	     prot_err->agent_type == LD || prot_err->agent_type == FMLD) &&
+	    !(prot_err->valid_bits & PROT_ERR_VALID_SERIAL_NUMBER))
+		pr_warn_ratelimited(FW_WARN
+				    "CXL CPER no device serial number\n");
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cxl_cper_sec_prot_err_valid);
+
+static void cxl_cper_post_prot_err(struct cxl_cper_sec_prot_err *prot_err,
+				   int severity)
+{
+	struct cxl_cper_prot_err_work_data wd;
+	u8 *dvsec_start, *cap_start;
+
+	if (cxl_cper_sec_prot_err_valid(prot_err))
+		return;
  
  	guard(spinlock_irqsave)(&cxl_cper_prot_err_work_lock);
  

diff --git a/include/cxl/event.h b/include/cxl/event.h
index 6fd90f9cc203..4d7d1036ea9c 100644
--- a/include/cxl/event.h
+++ b/include/cxl/event.h

@@ -320,4 +320,14 @@ static inline int cxl_cper_prot_err_kfifo_get(struct cxl_cper_prot_err_work_data
  }
  #endif
  
+#ifdef CONFIG_ACPI_APEI_PCIEAER
+int cxl_cper_sec_prot_err_valid(struct cxl_cper_sec_prot_err *prot_err);
+#else
+static inline int
+cxl_cper_sec_prot_err_valid(struct cxl_cper_sec_prot_err *prot_err)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
  #endif /* _LINUX_CXL_EVENT_H */