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=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 4E67BC65BAF for ; Wed, 12 Dec 2018 09:59:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1017420870 for ; Wed, 12 Dec 2018 09:59:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="jm9jiu+M" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1017420870 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=alien8.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727039AbeLLJ7s (ORCPT ); Wed, 12 Dec 2018 04:59:48 -0500 Received: from mail.skyhub.de ([5.9.137.197]:59110 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726598AbeLLJ7s (ORCPT ); Wed, 12 Dec 2018 04:59:48 -0500 Received: from zn.tnic (p200300EC2BCDD8002DC08A63FFF8C6E5.dip0.t-ipconnect.de [IPv6:2003:ec:2bcd:d800:2dc0:8a63:fff8:c6e5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 64C851EC0432; Wed, 12 Dec 2018 10:59:46 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1544608786; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=kCMnAg6KQ41PrBTldao0PLns3z+P7Bxi84CxeA2ECM4=; b=jm9jiu+MdBNL//yrYUnXeuRRPQ28V2KZYsmTwGIDCOmfhaW7SOT45knHgX/LhN/PyP7uHZ yJsjqe0zTx41zUmR6ut08XILQmkVCVAXd9AsDi+JwlABmt+asumonPHB0maB0ARdc6D3Y5 dzDxQmAsjZsce0rcFVD+ASSc7TXNSjA= Date: Wed, 12 Dec 2018 10:59:38 +0100 From: Borislav Petkov To: Thomas Gleixner Cc: "Lendacky, Thomas" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Andrea Arcangeli , Konrad Rzeszutek Wilk , Jiri Kosina , Ingo Molnar , Tim Chen , David Woodhouse Subject: Re: [PATCH v2] x86/speculation: Add support for STIBP always-on preferred mode Message-ID: <20181212095938.GA6653@zn.tnic> References: <20181211224615.5373.65736.stgit@tlendack-t1.amdoffice.net> <20181212000518.GX27375@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 11, 2018 at 07:37:26PM -0800, Thomas Gleixner wrote: > Hmmm. I've not seen the V1 of this (it's not in my inbox) but the v1->v2 > changes contain: You're on CC: https://lkml.kernel.org/r/20181211190959.28321.56433.stgit@tlendack-t1.amdoffice.net > > > > - Removed explicit SPECTRE_V2_USER_STRICT_PREFERRED mode > > Now I really have to ask why? > > Neither the extra variable nor the cpu feature check are pretty. An > explicit mode is way better in terms of code clarity and you get the proper > printout via spectre_v2_user_strings. Actually, now that I've slept on it, I think we should do this just like X86_FEATURE_IBRS_ENHANCED - as a modifier for SPECTRE_V2_CMD_AUTO or _FORCE options. And that has its own mode SPECTRE_V2_IBRS_ENHANCED. Makes sense? -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.