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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 872E4C433F5 for ; Fri, 13 May 2022 23:32:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229891AbiEMXb6 (ORCPT ); Fri, 13 May 2022 19:31:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40176 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229485AbiEMXbz (ORCPT ); Fri, 13 May 2022 19:31:55 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2BC6530BCFD for ; Fri, 13 May 2022 16:22:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1652484167; x=1684020167; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=KyCPdSxq6CFmcl2pjIuOEIvI0ilyCrZM3eYSgEPizRA=; b=Xue7+2qe/l0+NRfQOz/51GXcktB4EWOCG3KiI/y1l3jHtk0cpF+iW3oH Q3psj6eb74Fuax6hlNYDz7mt4EveTp+TvTb06TlsXDefY63MsUmUsVFy6 l0sXaK5B0v8djl4AQaYtzuo3i2+993/2j6Ez36KRv1rIDHLX1DcU3jn3a /N8mBDx+V0R/r7kXApChYqnSsytezuyeGBNcplV2i/biYGKmCDY47ILFe 50ba7+SKe8tWYLNQXV8yyfxXoG1l4lLEpGkd6f2SH8fY0nd6jijgMHSTI AIS892DUGvjALFyPmvRJrYQCVbFWlxvvFvIrcg+rngluV/APl2uLVRzjB A==; X-IronPort-AV: E=McAfee;i="6400,9594,10346"; a="268023276" X-IronPort-AV: E=Sophos;i="5.91,223,1647327600"; d="scan'208";a="268023276" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 May 2022 16:22:46 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,223,1647327600"; d="scan'208";a="815595889" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga006.fm.intel.com with ESMTP; 13 May 2022 16:22:43 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id EBD60A8; Sat, 14 May 2022 02:22:42 +0300 (EEST) Date: Sat, 14 May 2022 02:22:42 +0300 From: "Kirill A. Shutemov" To: Thomas Gleixner Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , x86@kernel.org, Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFCv2 08/10] x86/mm: Make LAM_U48 and mappings above 47-bits mutually exclusive Message-ID: <20220513232242.7ac7herw7iyfkd2h@black.fi.intel.com> References: <20220511022751.65540-1-kirill.shutemov@linux.intel.com> <20220511022751.65540-10-kirill.shutemov@linux.intel.com> <875ymax480.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <875ymax480.ffs@tglx> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 12, 2022 at 03:36:31PM +0200, Thomas Gleixner wrote: > On Wed, May 11 2022 at 05:27, Kirill A. Shutemov wrote: > > LAM_U48 steals bits above 47-bit for tags and makes it impossible for > > userspace to use full address space on 5-level paging machine. > > > Make these features mutually exclusive: whichever gets enabled first > > blocks the othe one. > > So this patch prevents a mapping above 47bit when LAM48 is enabled, but > I fail to spot how an already existing mapping above 47bit would prevent > LAM48 from being enabled. > > Maybe I'm missing something which makes this magically mutually > exclusive. It is in 09/10. See lam_u48_allowed() -- Kirill A. Shutemov