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

Marcelo Tosatti
2010-11-01T17:40:23Z

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?