4.4-stable review patch. If anyone has any objections, please let me know.
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From: Andy Lutomirski luto@kernel.org
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... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/include/asm/tlbflush.h | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -159,6 +159,15 @@ static inline void __native_flush_tlb_gl { unsigned long flags;
+ 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