From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934154AbcAYSiz (ORCPT ); Mon, 25 Jan 2016 13:38:55 -0500 Received: from mail.kernel.org ([198.145.29.136]:33280 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964921AbcAYShv (ORCPT ); Mon, 25 Jan 2016 13:37:51 -0500 From: Andy Lutomirski To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Borislav Petkov , Brian Gerst , Dave Hansen , Linus Torvalds , Oleg Nesterov , "linux-mm@kvack.org" , Andrey Ryabinin , Andy Lutomirski Subject: [PATCH v2 3/3] x86/mm: If INVPCID is available, use it to flush global mappings Date: Mon, 25 Jan 2016 10:37:44 -0800 Message-Id: X-Mailer: git-send-email 2.5.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 20fc38d8478a..4eba5164430d 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -145,6 +145,15 @@ static inline void __native_flush_tlb_global(void) { unsigned long flags; + if (static_cpu_has_safe(X86_FEATURE_INVPCID)) { + /* + * Using INVPCID is considerably faster than a pair of writes + * to CR4 sandwiched inside an IRQ flag save/restore. + */ + invpcid_flush_everything(); + return; + } + /* * Read-modify-write to CR4 - protect it from preemption and * from interrupts. (Use the raw variant because this code can -- 2.5.0