Re: [PATCH 2/2] KVM: Mask KVM_GET_SUPPORTED_CPUID data with Linux cpuid info

[Marcelo Tosatti <mtosatti@redhat.com>]

On Sun, Oct 24, 2010 at 03:38:46PM +0200, Avi Kivity wrote:
> This allows Linux to mask cpuid bits if, for example, nx is enabled on only
> some cpus.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
>  arch/x86/kvm/x86.c |    9 +++++++++
>  1 files changed, 9 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 48ce015..54fda7e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2229,6 +2229,11 @@ out:
>  	return r;
>  }
>  
> +static void cpuid_mask(u32 *word, int wordnum)
> +{
> +	*word &= boot_cpu_data.x86_capability[wordnum];
> +}
> +
>  static void do_cpuid_1_ent(struct kvm_cpuid_entry2 *entry, u32 function,
>  			   u32 index)
>  {
> @@ -2303,7 +2308,9 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
>  		break;
>  	case 1:
>  		entry->edx &= kvm_supported_word0_x86_features;
> +		cpuid_mask(&entry->edx, 0);
>  		entry->ecx &= kvm_supported_word4_x86_features;
> +		cpuid_mask(&entry->edx, 4);

ecx?

>  		/* we support x2apic emulation even if host does not support
>  		 * it since we emulate x2apic in software */
>  		entry->ecx |= F(X2APIC);
> @@ -2394,7 +2401,9 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
>  		break;
>  	case 0x80000001:
>  		entry->edx &= kvm_supported_word1_x86_features;
> +		cpuid_mask(&entry->edx, 1);
>  		entry->ecx &= kvm_supported_word6_x86_features;
> +		cpuid_mask(&entry->edx, 6);

ecx?