Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756686AbdDFPYu (ORCPT ); Thu, 6 Apr 2017 11:24:50 -0400 Received: from mail-wr0-f194.google.com ([209.85.128.194]:33628 "EHLO mail-wr0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753636AbdDFPYl (ORCPT ); Thu, 6 Apr 2017 11:24:41 -0400 Date: Thu, 6 Apr 2017 18:24:38 +0300 From: "Kirill A. Shutemov" To: Juergen Gross Cc: "Kirill A. Shutemov" , Linus Torvalds , Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , Dave Hansen , Andy Lutomirski , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 7/8] x86: Enable 5-level paging support Message-ID: <20170406152438.ekpu34qe2wzevf4h@node.shutemov.name> References: <20170406140106.78087-1-kirill.shutemov@linux.intel.com> <20170406140106.78087-8-kirill.shutemov@linux.intel.com> <469e1232-617c-daaa-90a6-a90d6f80059f@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <469e1232-617c-daaa-90a6-a90d6f80059f@suse.com> User-Agent: NeoMutt/20170306 (1.8.0) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1924 Lines: 62 On Thu, Apr 06, 2017 at 04:52:11PM +0200, Juergen Gross wrote: > On 06/04/17 16:01, Kirill A. Shutemov wrote: > > Most of things are in place and we can enable support of 5-level paging. > > > > Enabling XEN with 5-level paging requires more work. The patch makes XEN > > dependent on !X86_5LEVEL. > > > > Signed-off-by: Kirill A. Shutemov > > --- > > arch/x86/Kconfig | 5 +++++ > > arch/x86/xen/Kconfig | 1 + > > 2 files changed, 6 insertions(+) > > > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > > index 4e153e93273f..7a76dcac357e 100644 > > --- a/arch/x86/Kconfig > > +++ b/arch/x86/Kconfig > > @@ -318,6 +318,7 @@ config FIX_EARLYCON_MEM > > > > config PGTABLE_LEVELS > > int > > + default 5 if X86_5LEVEL > > default 4 if X86_64 > > default 3 if X86_PAE > > default 2 > > @@ -1390,6 +1391,10 @@ config X86_PAE > > has the cost of more pagetable lookup overhead, and also > > consumes more pagetable space per process. > > > > +config X86_5LEVEL > > + bool "Enable 5-level page tables support" > > + depends on X86_64 > > + > > config ARCH_PHYS_ADDR_T_64BIT > > def_bool y > > depends on X86_64 || X86_PAE > > diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig > > index 76b6dbd627df..b90d481ce5a1 100644 > > --- a/arch/x86/xen/Kconfig > > +++ b/arch/x86/xen/Kconfig > > @@ -5,6 +5,7 @@ > > config XEN > > bool "Xen guest support" > > depends on PARAVIRT > > + depends on !X86_5LEVEL > > select PARAVIRT_CLOCK > > select XEN_HAVE_PVMMU > > select XEN_HAVE_VPMU > > > > Just a heads up: this last change will conflict with the Xen tree. It should be trivial to fix, right? It's one-liner after all. > Can't we just ignore the additional level in Xen pv mode and run with > 4 levels instead? We don't have yet boot-time switching between paging modes yet. It will come later. So the answer is no. -- Kirill A. Shutemov