x86/cpu: Remove "nosmep"

There should be no need to disable SMEP anymore.

Signed-off-by: Borislav Petkov <[e-mail]>
Reviewed-by: Lai Jiangshan <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/admin-guide/kernel-parameters.txt

···
 			Disable SMAP (Supervisor Mode Access Prevention)
 			even if it is supported by processor.
 
-	nosmep		[X86,PPC64s]
+	nosmep		[PPC64s]
 			Disable SMEP (Supervisor Mode Execution Prevention)
 			even if it is supported by processor.
 

Documentation/x86/cpuinfo.rst

···
 
 In addition, there exists a variety of custom command-line parameters that
 disable specific features. The list of parameters includes, but is not limited
-to, nofsgsbase, and nosmep. 5-level paging can also be disabled using
-"no5lvl". SMEP is disabled with the aforementioned parameter.
+to, nofsgsbase, nosgx, noxsave, etc. 5-level paging can also be disabled using
+"no5lvl".
 
 e: The feature was known to be non-functional.
 ----------------------------------------------

arch/x86/kernel/cpu/common.c

···
 }
 #endif
 
-static __init int setup_disable_smep(char *arg)
-{
-	setup_clear_cpu_cap(X86_FEATURE_SMEP);
-	return 1;
-}
-__setup("nosmep", setup_disable_smep);
-
 static __always_inline void setup_smep(struct cpuinfo_x86 *c)
 {
 	if (cpu_has(c, X86_FEATURE_SMEP))