x86: Avoid check hlt for newer cpus

Check hlt instruction was targeted for some older CPUs. It is an expensive
operation in that it takes 4 ticks to break out the check. We can avoid
such check completely for newer x86 cpus (family >= 5).

[ hpa: corrected family > 5 to family >= 5 ]

Signed-off-by: Jacob Pan <[e-mail]>
LKML-Reference: <[e-mail]>
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/x86/kernel/cpu/bugs.c

···
 
 static void __init check_hlt(void)
 {
-	if (paravirt_enabled())
+	if (boot_cpu_data.x86 >= 5 || paravirt_enabled())
 		return;
 
 	printk(KERN_INFO "Checking 'hlt' instruction... ");