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Date:   Tue, 6 Mar 2018 08:04:37 +0100
From:   Ingo Molnar <mingo@kernel.org>
To:     "H. Peter Anvin" <hpa@zytor.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Joerg Roedel <joro@8bytes.org>,
        Brian Gerst <brgerst@gmail.com>,
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        Dave Hansen <dave.hansen@intel.com>,
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        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
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        Denys Vlasenko <dvlasenk@redhat.com>,
        Eduardo Valentin <eduval@amazon.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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Subject: Re: [PATCH 07/34] x86/entry/32: Restore segments before int registers
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* H. Peter Anvin <hpa@zytor.com> wrote:

> On NX-enabled hardware NX works with PDE, but the PDPDT in general doesn't
> have permission bits (it's really more of a set of four CR3s than a page
> table level.)

The 4 PDPDT entries are also shadowed in the CPU and are only refreshed
on CR3 loads, not spontaneously reloaded from memory during TLB walk
like regular page table entries, right?

This too strengthens the notion that the third page table level of PAE is more 
like a special in-memory CR3[4] array.

Thanks,

	Ingo