Re: [Xen-devel] Page tables in Xen

[tgh <wwwwww4187@xxxxxxxxxxx>]

hi
in the PV mode, when VM is migrated, the shadow page table will be 
created , that is ,the every active process pagetable in the guestOS 
will have a copy in the VMM, while the original one is maintianed as 
virtual-to-physical address mapping , is it right? then, when the 
guestOS process is scheduled , the shadow page table will be set into 
the CR3 and the CPU address mapping will be worked with the shadow 
pagetable rather than the original one, is it right? while every update 
to the process original pagetable in the guestOS will be trap into the 
VMM , where the shadow pagetable is updated and coherented with the 
original one, is it right?
Thanks in advance





Tim Deegan åé:
> At 20:12 +0800 on 05 Dec (1196885526), tgh wrote:
>   
> > hi
> >  in the PV mode,VM guestOS pagetable is virtual-to-machine address 
> > mapping,is it right?
> >     
> Yes.
>
>   
> > ,and when a VM is migrated, the shadow page table 
> > mode will be enabled ,is it right?
> >     
> Yes.
>
>   
> > then, the PVguestOS pagetalbe will 
> > become the virtual-to-psuedophysical address mapping, or not?
> >     
> Not.
>
>   
> >  then ,at 
> > that time ,the shadow pagetalbe is virtual-to-machine one ,is it right?
> >     
> Yes.
>  
>   
> >  I am still confused ,especially about the PVguestOS pagetalbe when 
> > shadow pagetable enabled for migration? is it a virtual-to-machine 
> > address mapping, or a virtual-to-psuedophysical address one ?
> >     
> *All* shadow pagetables are virtual-to-machine translations.  Anything
> else wouldn't be much use.
>
> Cheers,
>
> Tim.
>
>   

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