On Mon, May 16, 2011 at 02:11:40AM +0300, Nadav Har'El wrote:
> On Thu, May 12, 2011, Avi Kivity wrote about "Re: [PATCH 0/30] nVMX: Nested
> VMX, v9":
> > Ah, yes. For live migration to work, all vmcb state must be accessible
> > via vendor-independent accessors once an exit is completely handled.
> > For example, GPRs are accessible via kvm_register_read(), and without
> > nesting, interrupt state is stowed in the interrupt queue, but if you
> > keep IDT_VECTORING_INFO live between exit and entry, you can lose it if
> > you migrate at this point.
>
> Hi, I can quite easily save this state in a different place which is saved -
> The easiest will just be to use vmcs12, which has place for exactly the fields
> we want to save (and they are rewritten anyway when we exit to L1).
>
This will not address the problem that the state will not be visible to
generic logic in x86.c.
> Avi, would you you like me use this sort of solution to avoid the extra
> state? Of course, considering that anyway, live migration with nested VMX
> probably still doesn't work for a dozen other reasons :(
>
> Or do you consider this not enough, and rather that it is necessary that
> nested VMX should use exactly the same logic as nested SVM does - namely,
> use tricks like SVM's "exit_required" instead of our different tricks?
>
Given two solutions I prefer SVM one. Yes, I know that you asked Avi :)
--
Gleb.
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