Re: [PATCH 07/34] x86/entry/32: Restore segments before int registers

From: Ingo Molnar
Date: Tue Mar 06 2018 - 02:04:50 EST



* H. Peter Anvin <hpa@xxxxxxxxx> 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