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

["Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Thursday, December 06, 2012 7:46 PM
> To: Xu, Dongxiao
> Cc: Dong, Eddie; Nakajima, Jun; xen-devel@xxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH v3 03/11] nested vmx: expose bit 55 of
> IA32_VMX_BASIC_MSR to guest VMM
> 
> >>> 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.

Sure, will reflect in next pull request.

Thanks,
Dongxiao

> 
> Jan


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