From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74645C433DF for ; Tue, 19 May 2020 14:48:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 51630207FB for ; Tue, 19 May 2020 14:48:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729173AbgESOsR (ORCPT ); Tue, 19 May 2020 10:48:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59628 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727910AbgESOsR (ORCPT ); Tue, 19 May 2020 10:48:17 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1C0EC08C5C0 for ; Tue, 19 May 2020 07:48:16 -0700 (PDT) Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jb3XK-0002vY-Jc; Tue, 19 May 2020 16:48:06 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id C35C9100D01; Tue, 19 May 2020 16:48:05 +0200 (CEST) From: Thomas Gleixner To: David Laight , 'Sasha Levin' Cc: "linux-kernel\@vger.kernel.org" , "bp\@alien8.de" , "luto\@kernel.org" , "hpa\@zytor.com" , "dave.hansen\@intel.com" , "tony.luck\@intel.com" , "ak\@linux.intel.com" , "ravi.v.shankar\@intel.com" , "chang.seok.bae\@intel.com" , Andrew Cooper , "x86\@kernel.org" Subject: RE: [PATCH v12 10/18] x86/fsgsbase/64: Enable FSGSBASE instructions in helper functions In-Reply-To: <238a6e2609eb4e0497b13fbe5f531917@AcuMS.aculab.com> References: <20200511045311.4785-11-sashal@kernel.org> <87v9ktw1ev.fsf@nanos.tec.linutronix.de> <20200518202435.GD33628@sasha-vm> <238a6e2609eb4e0497b13fbe5f531917@AcuMS.aculab.com> Date: Tue, 19 May 2020 16:48:05 +0200 Message-ID: <87r1vg6kwq.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Laight writes: > From: Sasha Levin >> >> + native_swapgs(); >> >> + gsbase = rdgsbase(); >> >> + native_swapgs(); > > Does local_irq_save() even do anything useful here. > You need to actually execute CLI, not just set a > flag that indicates interrupts shouldn't happen. > (Which is what I think local_irq_save() might do.) local_irq_save() raw_local_irq_save() arch_local_irq_save() arch_local_irq_disable() native_irq_disable() asm("CLI") > You also (probably) need to disable NMIs. The NMI entry can deal with that obviously. Thanks, tglx