arch/x86/include/asm/nmi.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_NMI_H
#define _ASM_X86_NMI_H

#include <linux/irq_work.h>
#include <linux/pm.h>
#include <asm/irq.h>
#include <asm/io.h>

#ifdef CONFIG_X86_LOCAL_APIC

extern int reserve_perfctr_nmi(unsigned int);
extern void release_perfctr_nmi(unsigned int);
extern int reserve_evntsel_nmi(unsigned int);
extern void release_evntsel_nmi(unsigned int);

#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,
	NMI_SERR,
	NMI_IO_CHECK,
	NMI_MAX
};

/* NMI handler return values */
#define NMI_DONE	0
#define NMI_HANDLED	1

typedef int (*nmi_handler_t)(unsigned int, struct pt_regs *);

struct nmiaction {
	struct list_head	list;
	nmi_handler_t		handler;
	u64			max_duration;
	unsigned long		flags;
	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 = {	\
		.list = LIST_HEAD_INIT(fn##_na.list),	\
		.handler = (fn),			\
		.name = (n),				\
		.flags = (fg),				\
	};						\
	__register_nmi_handler((t), &fn##_na);		\
})

int __register_nmi_handler(unsigned int, struct nmiaction *);

/**
 * 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);

void stop_nmi(void);
void restart_nmi(void);
void local_touch_nmi(void);

#endif /* _ASM_X86_NMI_H */