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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 06667C282CB for ; Tue, 5 Feb 2019 17:09:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9151217F9 for ; Tue, 5 Feb 2019 17:09:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="igAXdNTA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730351AbfBERJL (ORCPT ); Tue, 5 Feb 2019 12:09:11 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:44798 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726717AbfBERJK (ORCPT ); Tue, 5 Feb 2019 12:09:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=9R9ZXCz0D3Q3SQKt5ylVRBb//IvkNJnDZEoY0+2+lyk=; b=igAXdNTA+VdYxB5R/7hWhXwf+ FueeB8VjYlzaMj8/It6/veiRVJW9H47NqmEHvO/qTdpoCHn/l+py7XC3Fc0LZS+TT3zdymOLQywGg Nff3B8nlpBIJDNK9cAEfujFS/SmRR8yRiyTL+2Ja317bBYo7NUi8QABSioBqb8R8q1SG4b5ExvghR FsNOS82bw/K48UuzLWXYQ7ApZYNW5rgpVIcO5ZKwq9rM++t2t7vlBixf94Nse2TuQ/JBuNy17OXMS w0EKIoGoI1gKdMEGlfFYHDfBkI59CwUbKkzdcHD1L5KjRtGssZfNpZi/mw/gDQhQMFrUUwZh50yVr iPHqYbhbg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gr4DZ-0002Rt-S7; Tue, 05 Feb 2019 17:09:06 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 4DD682029FA03; Tue, 5 Feb 2019 18:09:04 +0100 (CET) Date: Tue, 5 Feb 2019 18:09:04 +0100 From: Peter Zijlstra To: Dave Hansen Cc: Borislav Petkov , Thomas Gleixner , Fenghua Yu , Ingo Molnar , H Peter Anvin , Ashok Raj , Michael Chan , Ravi V Shankar , Ricardo Neri , linux-kernel , x86 Subject: Re: [PATCH v3 08/10] x86/setcpuid: Add kernel option setcpuid Message-ID: <20190205170904.GH17550@hirez.programming.kicks-ass.net> References: <1549084491-57808-1-git-send-email-fenghua.yu@intel.com> <1549084491-57808-9-git-send-email-fenghua.yu@intel.com> <9fa7406b-113f-fe0a-9fc7-ef00b3a6b620@intel.com> <20190204195704.GJ29639@zn.tnic> <5c2f0af3-1740-f16b-6ff6-6bec6a325034@intel.com> <20190204214044.GN29639@zn.tnic> <722af610-da30-2318-9ddd-d991238ce334@intel.com> <20190205061801.GC21801@zn.tnic> <92020eb5-e2c2-0b33-a366-784e36a69652@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <92020eb5-e2c2-0b33-a366-784e36a69652@intel.com> 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, Feb 05, 2019 at 08:46:23AM -0800, Dave Hansen wrote: > On 2/4/19 10:18 PM, Borislav Petkov wrote: > > Well, if it breaks old apps, it probably needs to be opt-in anyway. > > Yes, this was my assumption. It _should_ not break portable code (because RISC has much stronger #AC requirements). That said; I really do think we want it default enabled and allow individual apps to opt-out with a system-wide override to disable the opt-out. The cloud vendors and RT thingies will want to disable the opt-out for example.