From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752058AbdK0Mbk (ORCPT ); Mon, 27 Nov 2017 07:31:40 -0500 Received: from mail-io0-f177.google.com ([209.85.223.177]:35803 "EHLO mail-io0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751591AbdK0Mbj (ORCPT ); Mon, 27 Nov 2017 07:31:39 -0500 X-Google-Smtp-Source: AGs4zMZ7lmx6Sk5jtIBXdGFlzfOuMtfU5mcJgdcD0gYevJSbo0j596RgCY5U/Ewv/G7N0SAQEbYSONLw36aLLk/LRZg= MIME-Version: 1.0 In-Reply-To: References: <20171126231403.657575796@linutronix.de> <20171126232414.313869499@linutronix.de> <20171127095737.ocolhqaxsaboycwa@hirez.programming.kicks-ass.net> From: Brian Gerst Date: Mon, 27 Nov 2017 07:31:37 -0500 Message-ID: Subject: Re: [patch V2 1/5] x86/kaiser: Respect disabled CPU features To: Thomas Gleixner Cc: Peter Zijlstra , LKML , Dave Hansen , Andy Lutomirski , Ingo Molnar , Borislav Petkov , Denys Vlasenko , "H. Peter Anvin" , Josh Poimboeuf , Linus Torvalds , Rik van Riel , Daniel Gruss , Hugh Dickins , Kees Cook , Linux-MM , michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at, richard.fellner@student.tugraz.at Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 27, 2017 at 6:47 AM, Thomas Gleixner wrote: > On Mon, 27 Nov 2017, Peter Zijlstra wrote: >> On Mon, Nov 27, 2017 at 12:14:04AM +0100, Thomas Gleixner wrote: >> > PAGE_NX and PAGE_GLOBAL might be not supported or disabled on the command >> > line, but KAISER sets them unconditionally. >> >> So KAISER is x86_64 only, right? AFAIK there is no x86_64 without NX >> support. So would it not make sense to mandate NX for KAISER?, that is >> instead of making "noexec" + KAISER work, make "noexec" kill KAISER + >> emit a warning. > > OTOH, disabling NX is a simple way to verify that DEBUG_WX works correctly > also on the shadow maps. > > But surely we can drop the PAGE_GLOBAL thing, as all 64bit systems have it. I seem to recall that some virtualized environments (maybe Xen?) don't support global pages. -- Brian Gerst From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f198.google.com (mail-io0-f198.google.com [209.85.223.198]) by kanga.kvack.org (Postfix) with ESMTP id ABF686B0033 for ; Mon, 27 Nov 2017 07:31:39 -0500 (EST) Received: by mail-io0-f198.google.com with SMTP id w191so35015730iof.11 for ; Mon, 27 Nov 2017 04:31:39 -0800 (PST) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id l70sor6964980iol.152.2017.11.27.04.31.38 for (Google Transport Security); Mon, 27 Nov 2017 04:31:38 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <20171126231403.657575796@linutronix.de> <20171126232414.313869499@linutronix.de> <20171127095737.ocolhqaxsaboycwa@hirez.programming.kicks-ass.net> From: Brian Gerst Date: Mon, 27 Nov 2017 07:31:37 -0500 Message-ID: Subject: Re: [patch V2 1/5] x86/kaiser: Respect disabled CPU features Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner Cc: Peter Zijlstra , LKML , Dave Hansen , Andy Lutomirski , Ingo Molnar , Borislav Petkov , Denys Vlasenko , "H. Peter Anvin" , Josh Poimboeuf , Linus Torvalds , Rik van Riel , Daniel Gruss , Hugh Dickins , Kees Cook , Linux-MM , michael.schwarz@iaik.tugraz.at, moritz.lipp@iaik.tugraz.at, richard.fellner@student.tugraz.at On Mon, Nov 27, 2017 at 6:47 AM, Thomas Gleixner wrote: > On Mon, 27 Nov 2017, Peter Zijlstra wrote: >> On Mon, Nov 27, 2017 at 12:14:04AM +0100, Thomas Gleixner wrote: >> > PAGE_NX and PAGE_GLOBAL might be not supported or disabled on the command >> > line, but KAISER sets them unconditionally. >> >> So KAISER is x86_64 only, right? AFAIK there is no x86_64 without NX >> support. So would it not make sense to mandate NX for KAISER?, that is >> instead of making "noexec" + KAISER work, make "noexec" kill KAISER + >> emit a warning. > > OTOH, disabling NX is a simple way to verify that DEBUG_WX works correctly > also on the shadow maps. > > But surely we can drop the PAGE_GLOBAL thing, as all 64bit systems have it. I seem to recall that some virtualized environments (maybe Xen?) don't support global pages. -- Brian Gerst -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org