1 files changed, 46 insertions, 3 deletions

diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index f677382093f3..79d88d12c8fb 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -14,12 +14,26 @@ extern void release_perfctr_nmi(unsigned int);
 extern int reserve_evntsel_nmi(unsigned int);
 extern void release_evntsel_nmi(unsigned int);
 
-extern int unknown_nmi_panic;
-
 #endif /* CONFIG_X86_LOCAL_APIC */
 
+extern int unknown_nmi_panic;
+extern int panic_on_unrecovered_nmi;
+extern int panic_on_io_nmi;
+
+/* NMI handler flags */
 #define NMI_FLAG_FIRST	1
 
+/**
+ * enum - NMI types.
+ * @NMI_LOCAL:    Local NMI, CPU-specific NMI generated by the Local APIC.
+ * @NMI_UNKNOWN:  Unknown NMI, the source of the NMI may not be identified.
+ * @NMI_SERR:     System Error NMI, typically triggered by PCI errors.
+ * @NMI_IO_CHECK: I/O Check NMI, related to I/O errors.
+ * @NMI_MAX:      Maximum value for NMI types.
+ *
+ * NMI types are used to categorize NMIs and to dispatch them to the
+ * appropriate handler.
+ */
 enum {
 	NMI_LOCAL=0,
 	NMI_UNKNOWN,
@@ -28,6 +42,7 @@ enum {
 	NMI_MAX
 };
 
+/* NMI handler return values */
 #define NMI_DONE	0
 #define NMI_HANDLED	1
 
@@ -41,6 +56,25 @@ struct nmiaction {
 	const char		*name;
 };
 
+/**
+ * register_nmi_handler - Register a handler for a specific NMI type
+ * @t:    NMI type (e.g. NMI_LOCAL)
+ * @fn:   The NMI handler
+ * @fg:   Flags associated with the NMI handler
+ * @n:    Name of the NMI handler
+ * @init: Optional __init* attributes for struct nmiaction
+ *
+ * Adds the provided handler to the list of handlers for the specified
+ * NMI type. Handlers flagged with NMI_FLAG_FIRST would be executed first.
+ *
+ * Sometimes the source of an NMI can't be reliably determined which
+ * results in an NMI being tagged as "unknown". Register an additional
+ * handler using the NMI type - NMI_UNKNOWN to handle such cases. The
+ * caller would get one last chance to assume responsibility for the
+ * NMI.
+ *
+ * Return: 0 on success, or an error code on failure.
+ */
 #define register_nmi_handler(t, fn, fg, n, init...)	\
 ({							\
 	static struct nmiaction init fn##_na = {	\
@@ -54,7 +88,16 @@ struct nmiaction {
 
 int __register_nmi_handler(unsigned int, struct nmiaction *);
 
-void unregister_nmi_handler(unsigned int, const char *);
+/**
+ * unregister_nmi_handler - Unregister a handler for a specific NMI type
+ * @type: NMI type (e.g. NMI_LOCAL)
+ * @name: Name of the NMI handler used during registration
+ *
+ * Removes the handler associated with the specified NMI type from the
+ * NMI handler list. The "name" is used as a lookup key to identify the
+ * handler.
+ */
+void unregister_nmi_handler(unsigned int type, const char *name);
 
 void set_emergency_nmi_handler(unsigned int type, nmi_handler_t handler);