Re: swapping with MMU Notifiers V2

Joerg Roedel
2008-01-29T18:13:13Z

On Tue, Jan 29, 2008 at 07:02:52PM +0200, Avi Kivity wrote:
> Carsten Otte wrote:
> >Avi Kivity wrote:
> >>Every arch except s390 needs it. An ugly #ifndef CONFIG_KVM_HARDWARE_TLB_SYNC is preferred to duplicating
> >>the code.
> >BTW, from reading AMDs spec I don't expect NPT to need this vehicle for swapping either. They can just let
> >core-vm page out guest pages and will receive a proper page fault in the host. Jörg can you confirm that?
> >
>
> No, that doesn't work:
>
> - even though npt can use the same pagetable for guest and host, that isn't workable for kvm as npt doesn't
> have an offset/size thing. so kvm uses a separate pagetable for guest and host.

Right. We can't reuse page tables from the Linux MM for Nested Paging.

> - npt doesn't have a dual-tagged tlb, where a host tlb invalidate also invalidates all guest tlbs that point
> to the same page

Since we have our own page table for Nested Paging this is also true.

Joerg

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