Re: [PATCH] KVM : Fix read/write to IA32_FEATURE_CONTROL MSR in nested virt

[Paolo Bonzini <pbonzini@redhat.com>]

Il 03/07/2013 15:41, Arthur Chunqi Li ha scritto:
> Fix read/write to IA32_FEATURE_CONTROL MSR in nested environment.
> Simply return 0x5 when read and generate #GP(0) when write.
> Delete handling codes in vmx_set_vmx_msr() and generate #GP(0) in
> handle_wrmsr().
> 
> Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
> ---
>  arch/x86/kvm/vmx.c |    5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 260a919..e125f94 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2277,7 +2277,7 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
>  
>  	switch (msr_index) {
>  	case MSR_IA32_FEATURE_CONTROL:
> -		*pdata = 0;
> +		*pdata = 0x5;
>  		break;

This is not in the MSR_IA32_VMX_BASIC..MSR_IA32_VMX_TRUE_ENTRY_CTLS
range, so you must check nested_vmx_allowed and return 0 if it is false.

Otherwise looks good.

Paolo

>  	case MSR_IA32_VMX_BASIC:
>  		/*
> @@ -2356,9 +2356,6 @@ static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
>  	if (!nested_vmx_allowed(vcpu))
>  		return 0;
>  
> -	if (msr_index == MSR_IA32_FEATURE_CONTROL)
> -		/* TODO: the right thing. */
> -		return 1;
>  	/*
>  	 * No need to treat VMX capability MSRs specially: If we don't handle
>  	 * them, handle_wrmsr will #GP(0), which is correct (they are readonly)
>