Re: [RFC] Getting correct eip in skip_emulated_instruction()

[Avi Kivity <avi@redhat.com>]

Guillaume Thouvenin wrote:
> Hello,
>
>  Presently when we want to skip an emulated instruction we update the
> eip by reading the instruction length from VMCS structure and we add
> this value to the current eip. It gives us the new eip. A problem occurs
> when the guest state doesn't allow us to use VT because in that case,
> the values in VMCS structure are not up to date. That means that if we
> call skip_emulated_instruction() while guest state is invalid, the
> computed eip will be false.
>
>  To fix the problem I introduced a new field in the structure kvm_io to
> store the eip value if guest state is invalid. If the stored value is
> equal to 0 we read the length of the current instruction in VMCS and if
> not, we use it as the new eip. It works but I'm not really happy with
> that hack and I don't see how to solve the problem nicely.
>   

If we call the emulator we shouldn't call skip_emulated_instruction() in 
the first place, since the emulator already computes the next rip for 
us. I suggest moving ->skip_emulated_instruction() out of 
kvm_emulate_pio() and into handle_io() (and the svm equivalent).

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