Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751396AbeAHRT6 (ORCPT + 1 other); Mon, 8 Jan 2018 12:19:58 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:52191 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750710AbeAHRT5 (ORCPT ); Mon, 8 Jan 2018 12:19:57 -0500 Date: Mon, 8 Jan 2018 18:19:43 +0100 From: Peter Zijlstra To: Ingo Molnar Cc: Willy Tarreau , linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de, gnomes@lxorguk.ukuu.org.uk, torvalds@linux-foundation.org, Borislav Petkov , Josh Poimboeuf , Andy Lutomirski , Dave Hansen Subject: Re: [PATCH RFC 2/4] x86/arch_prctl: add ARCH_GET_NOPTI and ARCH_SET_NOPTI to enable/disable PTI Message-ID: <20180108171943.GC6176@hirez.programming.kicks-ass.net> References: <1515427939-10999-1-git-send-email-w@1wt.eu> <1515427939-10999-3-git-send-email-w@1wt.eu> <20180108170531.um2sb5wm6u4dc3rb@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180108170531.um2sb5wm6u4dc3rb@gmail.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Mon, Jan 08, 2018 at 06:05:31PM +0100, Ingo Molnar wrote: > Note that there is somewhat of a fuzzy detail regarding AMD CPUs which are marked > as 'Meltdown safe': should an explicit request to turn on PTI be honored by the > kernel? Should that be some sort of separate 'force PTI on' attribute? AMD should not have FEATURE_PTI enabled, and thus not end up in any code that cares about TIF_NOPTI.