The following commit has been merged into the x86/mm branch of tip:
Commit-ID: ebd3ad60a688131de7df1dd05fd2d7c57f542268
Gitweb: https://git.kernel.org/tip/ebd3ad60a688131de7df1dd05fd2d7c57f542268
Author: Borislav Petkov (AMD) <bp@xxxxxxxxx>
AuthorDate: Wed, 25 Jan 2023 08:50:13 +01:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 25 Jan 2023 10:32:06 +01:00
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: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230125075013.9292-1-bp@xxxxxxxxx
---
arch/x86/mm/tlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index c1e31e9..92d73cc 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 {
/*
|