[Qemu-devel] Re: POLL: Why do you use kqemu?

[Avi Kivity]

Jan Kiszka wrote:
> > When kvm write protects a guest page table in the shadow page table
> > entries pointing to that guest page, it should also write protect the
> > guest page table in the host page table entries to the same guest page.
> >     
>
> Ah, now I got it. What do other hypervisors do?
>   

As far as I can tell, Xen's head is in the sand too.  No idea about 
others.  I think qemu/tcg is fine.

> > > Does this still apply to nested paging? I guess (hope) not...
> > >   
> > >       
> > No, nested paging brings cancer and cures world peace.  Or something.
> >
> >     
>
> Well, then it's probably not worth bothering, at least until a real
> guest problem is explainable with this limitation. 

I agree.

> Are there any
> suspicious reports floating around (maybe not only about Windows)?
>   

Not that I'm aware of.  Paging page tables is tricky business.  Given 
that the pointed-to pages may have been evicted while the page table was 
in swap, I guess a guest would have to revalidate the entries anyway, 
thus triggering re-shadowing.

--
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