linux-kernel - Re: [PATCH 7/8] x86: Enable 5-level paging support

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Date:   Thu, 6 Apr 2017 17:56:47 +0200
From:   Juergen Gross <jgross@...e.com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>, 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>,
        linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 7/8] x86: Enable 5-level paging support

On 06/04/17 17:24, Kirill A. Shutemov wrote:
> 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 <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 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.

Right. Just wanted to mention it.


Juergen