Re: [PATCH v2 4/5] Viridian: populate CPUID leaf 6

[Andrew Cooper <andrew.cooper3@citrix.com>]

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On 24/06/13 08:06, Jan Beulich wrote:
> Properly reporting hardware features we use can only help Windows in
> making decisions towards its own performance tuning.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Does viridian allow for the possibility of these flags to change during
runtime, e.g. migrating an HVM domain from hardware supporting HAP to
hardware which can only manage shadow?

~Andrew

>
> --- a/xen/arch/x86/hvm/viridian.c
> +++ b/xen/arch/x86/hvm/viridian.c
> @@ -41,6 +41,11 @@
>  #define CPUID4A_MSR_BASED_APIC  (1 << 3)
>  #define CPUID4A_RELAX_TIMER_INT (1 << 5)
>  
> +/* Viridian CPUID 4000006, Implementation HW features detected and in use. */
> +#define CPUID6A_APIC_OVERLAY    (1 << 0)
> +#define CPUID6A_MSR_BITMAPS     (1 << 1)
> +#define CPUID6A_NESTED_PAGING   (1 << 3)
> +
>  int cpuid_viridian_leaves(unsigned int leaf, unsigned int *eax,
>                            unsigned int *ebx, unsigned int *ecx,
>                            unsigned int *edx)
> @@ -92,6 +97,15 @@ int cpuid_viridian_leaves(unsigned int l
>              *eax |= CPUID4A_MSR_BASED_APIC;
>          *ebx = 2047; /* long spin count */
>          break;
> +    case 6:
> +        /* Detected and in use hardware features. */
> +        if ( cpu_has_vmx_virtualize_apic_accesses )
> +            *eax |= CPUID6A_APIC_OVERLAY;
> +        if ( cpu_has_vmx_msr_bitmap || (read_efer() & EFER_SVME) )
> +            *eax |= CPUID6A_MSR_BITMAPS;
> +        if ( hap_enabled(d) )
> +            *eax |= CPUID6A_NESTED_PAGING;
> +        break;
>      }
>  
>      return 1;
>
>
>
>
>
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