Re: [Xen-devel] [PATCH v3 03/11] nested vmx: expose bit 55 of IA32_VMX_BASIC_MSR to guest VMM

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.12.12 at 02:09, Dongxiao Xu <dongxiao.xu@xxxxxxxxx> wrote:
> --- a/xen/include/asm-x86/hvm/vmx/vvmx.h
> +++ b/xen/include/asm-x86/hvm/vmx/vvmx.h
> @@ -45,6 +45,12 @@ struct nestedvmx {
>  /* bit 0-8, and 12 must be 1 */
>  #define VMX_ENTRY_CTLS_DEFAULT1              0x11ff
>  
> +/* 
> + * bit 55 of IA32_VMX_BASIC MSR, indicating whether any VMX controls that
> + * default to 1 may be cleared to 0.
> + */
> +#define VMX_BASIC_DEFAULT1_ZERO              (1ULL << 55)
> +
>  /*
>   * Encode of VMX instructions base on Table 24-11 & 24-12 of SDM 3B
>   */

I assume this relates to

        /*
         * To use EPT we expect to be able to clear certain intercepts.
         * We check VMX_BASIC_MSR[55] to correctly handle default controls.
         */
        uint32_t must_be_one, must_be_zero, msr = MSR_IA32_VMX_PROCBASED_CTLS;
        if ( vmx_basic_msr_high & (1u << 23) )
            msr = MSR_IA32_VMX_TRUE_PROCBASED_CTLS;

in xen/arch/x86/hvm/vmx/vmcs.c. If so, please use the new
constant there too, to point out that connection. That may
require moving this to a different header file.

Jan


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