Re: List of unaccessible x86 states

[Avi Kivity <avi@redhat.com>]

On 10/26/2009 12:45 PM, Joerg Roedel wrote:
>
> Ok, parts of the state can be saved in guest memory. But thats
> currently not done. This will need some care to not introduce a security
> hole. But it shouldn't be too difficult.
> The state thats not reproducible in an sane way is the intercept bitmap
> for the l2 guest.
>  From the nested state what needs to be exposed to userspace for
> migration is:
>
> * guest mode flag (as returned by is_nested)
> * nested vmcb address
>    

Yes, forgot that.  We can store it in the hsave area (note the hsave 
area format becomes an ABI).

> * nested hsave msr
>    

That's already saved.

> * nested intercepts
>    

These are part of the guest vmcb.  The host nested intercepts can be 
recalculated, no?

> * for nested nested paging: guest nested cr3 value
>    

Part of the guest vmcb.

> Another state which needs exposure is the last branch record related
> state.
>    

Aren't those just more MSRs?

> Off-topic question: Will the new migration protocol include some kind
>                 handshake to find out if migration is possible at all?
>
>    

It's assumed that migration always works for a newer qemu version, and 
that the management tools don't attempt backward migration.

-- 
error compiling committee.c: too many arguments to function