Re: [Qemu-devel] [PATCH] i386: derive '-cpu host' from KVM_GET_SUPPORTED_CPUID

[Anthony Liguori]

On 11/09/2011 07:44 AM, Avi Kivity wrote:
> The fact that a host cpu supports a feature doesn't mean that QEMU and KVM
> will also support it, yet -cpuid host brings host features wholesale.
>
> We need to whitelist each feature separately to make sure we support it.
> This patch adds KVM whitelisting (by simply using KVM_GET_SUPPORTED_CPUID
> instead of the CPUID instruction).
>
> Signed-off-by: Avi Kivity<address@hidden>

Applied.  Thanks.

Regards,

Anthony Liguori

> ---
>   target-i386/cpuid.c |   27 ++++-----------------------
>   1 files changed, 4 insertions(+), 23 deletions(-)
>
> diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c
> index 1e8bcff..edac377 100644
> --- a/target-i386/cpuid.c
> +++ b/target-i386/cpuid.c
> @@ -107,33 +107,14 @@ void host_cpuid(uint32_t function, uint32_t count,
>                   uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx)
>   {
>   #if defined(CONFIG_KVM)
> -    uint32_t vec[4];
> -
> -#ifdef __x86_64__
> -    asm volatile("cpuid"
> -                 : "=a"(vec[0]), "=b"(vec[1]),
> -                   "=c"(vec[2]), "=d"(vec[3])
> -                 : "0"(function), "c"(count) : "cc");
> -#else
> -    asm volatile("pusha \n\t"
> -                 "cpuid \n\t"
> -                 "mov %%eax, 0(%2) \n\t"
> -                 "mov %%ebx, 4(%2) \n\t"
> -                 "mov %%ecx, 8(%2) \n\t"
> -                 "mov %%edx, 12(%2) \n\t"
> -                 "popa"
> -                 : : "a"(function), "c"(count), "S"(vec)
> -                 : "memory", "cc");
> -#endif
> -
>       if (eax)
> -        *eax = vec[0];
> +        *eax = kvm_arch_get_supported_cpuid(kvm_state, function, count, R_EAX);
>       if (ebx)
> -        *ebx = vec[1];
> +        *ebx = kvm_arch_get_supported_cpuid(kvm_state, function, count, R_EBX);
>       if (ecx)
> -        *ecx = vec[2];
> +        *ecx = kvm_arch_get_supported_cpuid(kvm_state, function, count, R_ECX);
>       if (edx)
> -        *edx = vec[3];
> +        *edx = kvm_arch_get_supported_cpuid(kvm_state, function, count, R_EDX);
>   #endif
>   }