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Commit 731dc9df authored by Tyler Hicks's avatar Tyler Hicks Committed by Thomas Gleixner
Browse files

cpu/speculation: Uninline and export CPU mitigations helpers 



A kernel module may need to check the value of the "mitigations=" kernel
command line parameter as part of its setup when the module needs
to perform software mitigations for a CPU flaw.

Uninline and export the helper functions surrounding the cpu_mitigations
enum to allow for their usage from a module.

Lastly, privatize the enum and cpu_mitigations variable since the value of
cpu_mitigations can be checked with the exported helper functions.

Signed-off-by: default avatarTyler Hicks <tyhicks@canonical.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent cad14885

include/linux/cpu.h

+2 −23
Original line number Diff line number Diff line
@@ -218,28 +218,7 @@ static inline int cpuhp_smt_enable(void) { return 0; } 
static inline int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) { return 0; }

#endif



/*

 * These are used for a global "mitigations=" cmdline option for toggling

 * optional CPU mitigations.

 */

enum cpu_mitigations {

	CPU_MITIGATIONS_OFF,

	CPU_MITIGATIONS_AUTO,

	CPU_MITIGATIONS_AUTO_NOSMT,

};



extern enum cpu_mitigations cpu_mitigations;



/* mitigations=off */

static inline bool cpu_mitigations_off(void)

{

	return cpu_mitigations == CPU_MITIGATIONS_OFF;

}



/* mitigations=auto,nosmt */

static inline bool cpu_mitigations_auto_nosmt(void)

{

	return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT;

}

extern bool cpu_mitigations_off(void);

extern bool cpu_mitigations_auto_nosmt(void);



#endif /* _LINUX_CPU_H_ */

kernel/cpu.c

+26 −1
Original line number Diff line number Diff line
@@ -2373,7 +2373,18 @@ void __init boot_cpu_hotplug_init(void) 
	this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);

}



enum cpu_mitigations cpu_mitigations __ro_after_init = CPU_MITIGATIONS_AUTO;

/*

 * These are used for a global "mitigations=" cmdline option for toggling

 * optional CPU mitigations.

 */

enum cpu_mitigations {

	CPU_MITIGATIONS_OFF,

	CPU_MITIGATIONS_AUTO,

	CPU_MITIGATIONS_AUTO_NOSMT,

};



static enum cpu_mitigations cpu_mitigations __ro_after_init =

	CPU_MITIGATIONS_AUTO;



static int __init mitigations_parse_cmdline(char *arg)

{
@@ -2390,3 +2401,17 @@ static int __init mitigations_parse_cmdline(char *arg) 
	return 0;

}

early_param("mitigations", mitigations_parse_cmdline);



/* mitigations=off */

bool cpu_mitigations_off(void)

{

	return cpu_mitigations == CPU_MITIGATIONS_OFF;

}

EXPORT_SYMBOL_GPL(cpu_mitigations_off);



/* mitigations=auto,nosmt */

bool cpu_mitigations_auto_nosmt(void)

{

	return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT;

}

EXPORT_SYMBOL_GPL(cpu_mitigations_auto_nosmt);