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 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 EF482CA90AF for ; Wed, 13 May 2020 14:16:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AEB8620675 for ; Wed, 13 May 2020 14:16:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388909AbgEMOQ3 (ORCPT ); Wed, 13 May 2020 10:16:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388896AbgEMOQ1 (ORCPT ); Wed, 13 May 2020 10:16:27 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72B40C061A0C for ; Wed, 13 May 2020 07:16:27 -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 1jYsBF-0004rs-6l; Wed, 13 May 2020 16:16:17 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 9CBB1100605; Wed, 13 May 2020 16:16:16 +0200 (CEST) From: Thomas Gleixner To: Balbir Singh , linux-kernel@vger.kernel.org Cc: jpoimboe@redhat.com, tony.luck@intel.com, keescook@chromium.org, benh@kernel.crashing.org, x86@kernel.org, dave.hansen@intel.com, thomas.lendacky@amd.com, Balbir Singh Subject: Re: [PATCH v6 3/6] arch/x86/mm: Refactor cond_ibpb() to support other use cases In-Reply-To: <20200510014803.12190-4-sblbir@amazon.com> References: <20200510014803.12190-1-sblbir@amazon.com> <20200510014803.12190-4-sblbir@amazon.com> Date: Wed, 13 May 2020 16:16:16 +0200 Message-ID: <87h7wj3opb.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 Balbir Singh writes: > @@ -550,8 +549,10 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next, > * Avoid user/user BTB poisoning by flushing the branch > * predictor when switching between processes. This stops > * one process from doing Spectre-v2 attacks on another. > + * The hook can also be used for mitigations that rely > + * on switch_mm for hooks. The new function name has absolutely nothing to do with IBPB and is clearly talking about mitigations. So the IBPB comment wants to move and that extra sentence you bolted on can go away. It's nonsensical word salad anyway. > > /* Reinitialize tlbstate. */ > - this_cpu_write(cpu_tlbstate.last_user_mm_ibpb, LAST_USER_MM_IBPB); > + this_cpu_write(cpu_tlbstate.last_user_mm_spec, LAST_USER_MM_IBPB); There is still no comment why this only needs MM_IBPB. I'll change this to LAST_USER_MM_INIT and put that define close to the others. Thanks, tglx