linux-kernel - Re: [PATCHv5, REBASED 8/9] x86: Enable 5-level paging support

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Date:   Mon, 15 May 2017 17:11:19 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Juergen Gross <jgross@...e.com>
Cc:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Andy Lutomirski <luto@...capital.net>,
        Dan Williams <dan.j.williams@...el.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv5, REBASED 8/9] x86: Enable 5-level paging support

On Mon, May 15, 2017 at 02:31:00PM +0200, Juergen Gross wrote:
> > diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
> > index 027987638e98..12205e6dfa59 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
> 
> I'd rather put this under "config XEN_PV".

Makes sense.

----------------------8<----------------------------

>From 422a980c748a5b84a013258eb7c00d61edc34492 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Date: Sat, 5 Nov 2016 03:24:03 +0300
Subject: [PATCHv6 8/9] x86: Enable 5-level paging support

Most of things are in place and we can enable support of 5-level paging.

The patch makes XEN_PV dependent on !X86_5LEVEL. XEN_PV is not ready to
work with 5-level paging.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 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 cd18994a9555..11bd0498f64c 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 027987638e98..1be9667bd476 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -17,6 +17,7 @@ config XEN_PV
 	bool "Xen PV guest support"
 	default y
 	depends on XEN
+	depends on !X86_5LEVEL
 	select XEN_HAVE_PVMMU
 	select XEN_HAVE_VPMU
 	help
-- 
 Kirill A. Shutemov