x86/cpu: Remove unnecessary MwAIT leaf checks

The CPUID leaf dependency checker will remove X86_FEATURE_MWAIT if
the CPUID level is below the required level (CPUID_MWAIT_LEAF).
Thus, if you check X86_FEATURE_MWAIT you do not need to also
check the CPUID level.

Signed-off-by: Dave Hansen <[email protected]>
Link: https://lore.kernel.org/all/20241213205030.9B42B458%40davehans-spike.ostc.intel.com

Author: hansendc

arch/x86/kernel/hpet.c

@@ -928,9 +928,6 @@ static bool __init mwait_pc10_supported(void)
 	if (!cpu_feature_enabled(X86_FEATURE_MWAIT))
 		return false;
 
-	if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
-		return false;
-
 	cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
 
 	return (ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) &&

arch/x86/kernel/smpboot.c

@@ -1292,8 +1292,6 @@ static inline void mwait_play_dead(void)
 		return;
 	if (!this_cpu_has(X86_FEATURE_CLFLUSH))
 		return;
-	if (__this_cpu_read(cpu_info.cpuid_level) < CPUID_MWAIT_LEAF)
-		return;
 
 	eax = CPUID_MWAIT_LEAF;
 	ecx = 0;

drivers/acpi/acpi_pad.c

@@ -47,8 +47,6 @@ static void power_saving_mwait_init(void)
 
 	if (!boot_cpu_has(X86_FEATURE_MWAIT))
 		return;
-	if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
-		return;
 
 	cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
 

drivers/idle/intel_idle.c

@@ -2317,9 +2317,6 @@ static int __init intel_idle_init(void)
 			return -ENODEV;
 	}
 
-	if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
-		return -ENODEV;
-
 	cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
 
 	if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||