| From: Andy Lutomirski <luto@kernel.org> |
| Date: Fri, 29 Jan 2016 11:42:59 -0800 |
| Subject: x86/mm: If INVPCID is available, use it to flush global mappings |
| |
| commit d8bced79af1db6734f66b42064cc773cada2ce99 upstream. |
| |
| On my Skylake laptop, INVPCID function 2 (flush absolutely |
| everything) takes about 376ns, whereas saving flags, twiddling |
| CR4.PGE to flush global mappings, and restoring flags takes about |
| 539ns. |
| |
| Signed-off-by: Andy Lutomirski <luto@kernel.org> |
| Reviewed-by: Borislav Petkov <bp@suse.de> |
| Cc: Andrew Morton <akpm@linux-foundation.org> |
| Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> |
| Cc: Andy Lutomirski <luto@amacapital.net> |
| Cc: Borislav Petkov <bp@alien8.de> |
| Cc: Brian Gerst <brgerst@gmail.com> |
| Cc: Dave Hansen <dave.hansen@linux.intel.com> |
| Cc: Denys Vlasenko <dvlasenk@redhat.com> |
| Cc: H. Peter Anvin <hpa@zytor.com> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: Luis R. Rodriguez <mcgrof@suse.com> |
| Cc: Oleg Nesterov <oleg@redhat.com> |
| Cc: Peter Zijlstra <peterz@infradead.org> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Cc: Toshi Kani <toshi.kani@hp.com> |
| Cc: linux-mm@kvack.org |
| Link: http://lkml.kernel.org/r/ed0ef62581c0ea9c99b9bf6df726015e96d44743.1454096309.git.luto@kernel.org |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Cc: Hugh Dickins <hughd@google.com> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| arch/x86/include/asm/tlbflush.h | 9 +++++++++ |
| 1 file changed, 9 insertions(+) |
| |
| diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h |
| index 24bf6a3b2948..190b1cf3a7ce 100644 |
| --- a/arch/x86/include/asm/tlbflush.h |
| +++ b/arch/x86/include/asm/tlbflush.h |
| @@ -80,6 +80,15 @@ static inline void __native_flush_tlb_global(void) |
| unsigned long flags; |
| unsigned long cr4; |
| |
| + if (static_cpu_has(X86_FEATURE_INVPCID)) { |
| + /* |
| + * Using INVPCID is considerably faster than a pair of writes |
| + * to CR4 sandwiched inside an IRQ flag save/restore. |
| + */ |
| + invpcid_flush_all(); |
| + return; |
| + } |
| + |
| /* |
| * Read-modify-write to CR4 - protect it from preemption and |
| * from interrupts. (Use the raw variant because this code can |
| |