Re: swapping with MMU Notifiers V2

Carsten Otte
2008-01-30T11:26:39Z

Andrea Arcangeli wrote:
> By your conclusion I suppose you thought NPT maps guest physical to
> host virtual. If it was the case the cpu would to walk three layer of
> pagetables (each layer is an arrow): guest virtual -> guest physical
> -> host virtual -> host physical. Instead it's just guest virtual ->
> guest physical -> host physical. Or even less for shadow: guest
> virtual -> host physical, which is why shadow should be faster for
> number crunching still (and definitely slower for dbms).
No, I was assuming guest virtual -> guest physical -> host physical.
We do the same. We just re-use the very same page table that maps gp
to hp to map host userland to hp. The only tricky part for AMD64 is to
hide host userland parts from the guest that are not supposed to be
visible to the guest-os as far as I see.