Re: [PATCH v3 3/6] KVM: nVMX: Load nEPT state after EFER

[Gleb Natapov <gleb@redhat.com>]

On Thu, Aug 08, 2013 at 04:26:30PM +0200, Jan Kiszka wrote:
> We need to update EFER.NX before building the nEPT state via
> nested_ept_init_mmu_context. Otherwise, we risk to create an MMU context
> that claims to have NX disabled while the guest EPT used NX. This will
> cause spurious faults for L2.
> 
Hmm, I do not see how nested ept mmu depends on guests EFER.NX setting.
It just sets mmu->nx to true.

> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  arch/x86/kvm/vmx.c |   10 +++++-----
>  1 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 6c42518..363fe19 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -7727,11 +7727,6 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
>  		vmx_flush_tlb(vcpu);
>  	}
>  
> -	if (nested_cpu_has_ept(vmcs12)) {
> -		kvm_mmu_unload(vcpu);
> -		nested_ept_init_mmu_context(vcpu);
> -	}
> -
>  	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER)
>  		vcpu->arch.efer = vmcs12->guest_ia32_efer;
>  	else if (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE)
> @@ -7741,6 +7736,11 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
>  	/* Note: modifies VM_ENTRY/EXIT_CONTROLS and GUEST/HOST_IA32_EFER */
>  	vmx_set_efer(vcpu, vcpu->arch.efer);
>  
> +	if (nested_cpu_has_ept(vmcs12)) {
> +		kvm_mmu_unload(vcpu);
> +		nested_ept_init_mmu_context(vcpu);
> +	}
> +
>  	/*
>  	 * This sets GUEST_CR0 to vmcs12->guest_cr0, with possibly a modified
>  	 * TS bit (for lazy fpu) and bits which we consider mandatory enabled.
> -- 
> 1.7.3.4

--
			Gleb.