On 03/05/2018 11:04 PM, Ingo Molnar wrote:
> * H. Peter Anvin <h...@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?
Yes. The SDM even calls them non-architectural "PDPTE Registers" and
talks about them only being loaded at CR3 write time.
~5 years ago we even had a bug directly related to this feature: