Re: mmiotrace bug: recursive probe hit

[Avi Kivity]

Avi Kivity wrote:
> > For kmemcheck, I'd prefer the per-CPU page tables suggested by Ingo.
> > I'm having hard time understanding why that's a "ugly hack" compared
> > to using kvm for this...
> >   
>
> It's not an ugly hack, but will be very very difficult.  With mmu 
> notifiers it's probably doable though:
>
> - the linux page tables are never loaded into cr3, but rather kept as 
> a reference
> - page faults are by instantiating ptes into shadow page tables (which 
> track the linux page tables)
> - mmu notifiers are used to drop shadow ptes when the linux ptes change

Actually, paravirt_ops is a much better match, as it also provides hooks 
for setting cr3.  I think you can implement per-cpu pagetables using 
paravirt_ops without modifying core mm code at all.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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