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Date: Tue, 16 Jan 2018 22:06:48 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Joerg Roedel <joro@8bytes.org>
cc: Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>,
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Subject: Re: [PATCH 10/16] x86/mm/pti: Populate valid user pud entries
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On Tue, 16 Jan 2018, Joerg Roedel wrote:

> From: Joerg Roedel <jroedel@suse.de>
> 
> With PAE paging we don't have PGD and P4D levels in the
> page-table, instead the PUD level is the highest one.
> 
> In PAE page-tables at the top-level most bits we usually set
> with _KERNPG_TABLE are reserved, resulting in a #GP when
> they are loaded by the processor.
> 
> Work around this by populating PUD entries in the user
> page-table only with _PAGE_PRESENT set.
> 
> I am pretty sure there is a cleaner way to do this, but
> until I find it use this #ifdef solution.

Stick somehting like

#define _KERNELPG_TABLE_PUD_ENTRY

into the 32 and 64 bit variants of some relevant header file 

Thanks,

	tglx