int nmi_reserve_counters(void)
{
if (!allocate_msrs())
return -ENOMEM;
/* We walk a thin line between law and rape here.
* We need to be careful to install our NMI handler
* without actually triggering any NMIs as this will
* break the core code horrifically.
*/
if (reserve_lapic_nmi() < 0) {
free_msrs();
return -EBUSY;
}
/* We need to serialize save and setup for HT because the subset
* of msrs are distinct for save and setup operations
*/
on_each_cpu(nmi_save_registers, NULL, 1);
return 0;
}
/*
* proc handler for /proc/sys/kernel/unknown_nmi_panic
*/
int proc_unknown_nmi_panic(struct ctl_table *table, int write, struct file *file,
void __user *buffer, size_t *length, loff_t *ppos)
{
int old_state;
old_state = unknown_nmi_panic;
proc_dointvec(table, write, file, buffer, length, ppos);
if (!!old_state == !!unknown_nmi_panic)
return 0;
if (unknown_nmi_panic) {
if (reserve_lapic_nmi() < 0) {
unknown_nmi_panic = 0;
return -EBUSY;
} else {
set_nmi_callback(unknown_nmi_panic_callback);
}
} else {
release_lapic_nmi();
unset_nmi_callback();
}
return 0;
}