diff mbox series

x86/cpu: Use cpu_feature_enabled() when checking global pages support

Message ID 20230125075013.9292-1-bp@alien8.de
State New
Headers
Series x86/cpu: Use cpu_feature_enabled() when checking global pages support |

Commit Message

Borislav Petkov Jan. 25, 2023, 7:50 a.m. UTC 
  From: "Borislav Petkov (AMD)" <bp@alien8.de>

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: Borislav Petkov (AMD) <bp@alien8.de>
---
 arch/x86/mm/tlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index c1e31e9a85d7..92d73ccede70 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -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 {
 		/*