Commit ebd3ad60 authored by Borislav Petkov (AMD)'s avatar Borislav Petkov (AMD) Committed by Ingo Molnar
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x86/cpu: Use cpu_feature_enabled() when checking global pages support 



X86_FEATURE_PGE determines whether the CPU has enabled global page
translations support. Use the faster cpu_feature_enabled() check to
shave off some more cycles when flushing all TLB entries, including the
global ones.

What this practically saves is:

   mov    0x82eb308(%rip),%rax        # 0xffffffff8935bec8 <boot_cpu_data+40>
   test   $0x20,%ah

... which test the bit. Not a lot, but TLB flushing is a timing-sensitive
path, so anything to make it even faster.

No functional changes.

Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230125075013.9292-1-bp@alien8.de
parent 2241ab53

arch/x86/mm/tlb.c

+1 −1
Original line number Diff line number Diff line
@@ -1205,7 +1205,7 @@ void __flush_tlb_all(void) 
	 */

	VM_WARN_ON_ONCE(preemptible());



	if (boot_cpu_has(X86_FEATURE_PGE)) {

	if (cpu_feature_enabled(X86_FEATURE_PGE)) {

		__flush_tlb_global();

	} else {

		/*