Re: [PATCH v4 1/4] Nested VMX: check VMX capability before read VMX related MSRs

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 09/23/2013 06:10 AM, Jan Beulich wrote:
> --- a/xen/arch/x86/hvm/vmx/vvmx.c
> +++ b/xen/arch/x86/hvm/vmx/vvmx.c
> @@ -1813,12 +1813,33 @@ int nvmx_handle_invvpid(struct cpu_user_
>   int nvmx_msr_read_intercept(unsigned int msr, u64 *msr_content)
>   {
>       struct vcpu *v = current;
> +    unsigned int ecx, dummy;
>       u64 data = 0, host_data = 0;
>       int r = 1;
>   
>       if ( !nestedhvm_enabled(v->domain) )
>           return 0;
>   
> +    /* VMX capablity MSRs are available only when guest supports VMX. */
> +    hvm_cpuid(0x1, &dummy, &dummy, &ecx, &dummy);

Depending on order in which you are going to commit patches you could 
change hvm_cpuid() dummy arguments to NULLs to make use of your "make 
hvm_cpuid() ..." patch. In [3/4] as well.


-boris