Registers need to recover when emulating L2 vmexit

Registers need to recover when emulating L2 vmexit

[Arthur Chunqi Li]

Hi Gleb and Paolo,
>From current KVM codes, when L2 cause VMEXIT or L1 fails to enter L2,
host VMX will execute nested_vmx_vmexit() and
nested_vmx_entry_failure(). Both of them calls
load_vmcs12_host_state() which loads vmcs12's HOST fields as vmcs01's
GUEST fields. But the HOST and GUEST fields are not accurately
correspondence, e.g. GUEST_CS/ES..._BASE/LIMIT/AR. What will these
MSRs be set?

Thanks,
Arthur

--
Arthur Chunqi Li
Department of Computer Science
School of EECS
Peking University
Beijing, China

Re: Registers need to recover when emulating L2 vmexit

[Gleb Natapov]

On Mon, Jul 08, 2013 at 07:50:45PM +0800, Arthur Chunqi Li wrote:
> Hi Gleb and Paolo,
> >From current KVM codes, when L2 cause VMEXIT or L1 fails to enter L2,
> host VMX will execute nested_vmx_vmexit() and
> nested_vmx_entry_failure(). Both of them calls
> load_vmcs12_host_state() which loads vmcs12's HOST fields as vmcs01's
> GUEST fields. But the HOST and GUEST fields are not accurately
> correspondence, e.g. GUEST_CS/ES..._BASE/LIMIT/AR. What will these
> MSRs be set?
> 
This is not MSRs, but VMCS field. Currently they are set to whatever
value they had in vmcs01 when L1 executed VMLAUNCH, but this is
incorrect. They should be set according to section 27.5.2
"Loading Host Segment and Descriptor-Table Registers" of SDM.

--
			Gleb.