Re: problem with vm-exit exit code

[Avi Kivity <avi@redhat.com>]

On 01/19/2010 01:09 AM, Matteo Signorini wrote:
> Hi guys,
>
> I would like to intercept the vm-exit whenever the guest executes a
> lidt/sidt instruction.
> I know that lidt/sidt instructions cause a vm-exit if and only if
> these condition are satisfied:
>
>     -commands are executed in vmx non-root environment
>     -the "descriptor-table exiting" field of the secondary vm-execution
> control structure is enabled
>
> The first condition is satisfied because the guest OS executes the
> lidt/sidt in the boot routine so we are in the vmx non-root
> environment.
> To satisfy the second condition, I set up the 31th bit in the primary
> vm-execution control to 1 to enable the secondary vm-execution
> control,
> then I set up the 2nd bit of the secondary vm-execution control to 1
> to enable the "descriptor-table exiting".
>
> The problem is that I never get the exit_code=46 (that should
> correspond to the IDTR access as shown in the Intel developer's
> manual).
> What I get is exit_code=0 and then the VM freezes.
>
> I wonder why I get 0 as exit reason instead of 46?
>
> Qemu gives me the following error message:
> "kvm: unhandled exit 7
> kvm_run returned -22"
>
> The unhandled exit code correspond to the 7th vm-instruction error
> number referred to: "VM-Entry with invalid control field(s)"
>    

Did you check whether your processor supports descriptor-table exiting?

The 'vmxcap' script can help determine that.

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