Re: [Qemu-devel] [PATCH 08/20] target-i386: move kvm_check_features_against_host() check to realize time

[Eduardo Habkost]

On Thu, Dec 27, 2012 at 03:59:24PM +0100, Igor Mammedov wrote:
> kvm_check_features_against_host() should be called when features can't be 
> changed
> and when features are convereted to properties it would be possible to change 
> them
> until realize time, so correct way is to call 
> kvm_check_features_against_host() in
> x86_cpu_realize()
> 
>  - calling kvm_check_features_against_host() makes sense only when qemu is 
> compiled
>    --enable-kvm, so move it inside CONFIG_KVM ifdef and compile it and
>    other kvm specific functions only if CONFIG_KVM is defined to avoid *-user 
> target
>    build breakage.
> 
> Signed-off-by: Igor Mammedov <address@hidden>

Commit message has more than 80 columns.

But considering that the code changes look OK:

Reviewed-by: Eduardo Habkost <address@hidden>

We can probably #ifdef-out the whole host_cpuid() function as well. But
that can be done in a separate patch, as it requires more testing to
make sure it won't cause unexpected build errors on some configurations
(as the function is not static).


> ---
>  v2:
>    - squash in ifdef-ing kvm specific functions into this patch
> ---
>  target-i386/cpu.c |   27 +++++++++++++++------------
>  1 files changed, 15 insertions(+), 12 deletions(-)
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 97cce89..d93bf5a 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -862,7 +862,6 @@ static int cpu_x86_fill_model_id(char *str)
>      }
>      return 0;
>  }
> -#endif
>  
>  /* Fill a x86_def_t struct with information about the host CPU, and
>   * the CPU features supported by the host hardware + host kernel
> @@ -871,7 +870,6 @@ static int cpu_x86_fill_model_id(char *str)
>   */
>  static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
>  {
> -#ifdef CONFIG_KVM
>      KVMState *s = kvm_state;
>      uint32_t eax = 0, ebx = 0, ecx = 0, edx = 0;
>  
> @@ -930,7 +928,6 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
>       * unsupported ones later.
>       */
>      x86_cpu_def->svm_features = -1;
> -#endif /* CONFIG_KVM */
>  }
>  
>  static int unavailable_host_feature(struct model_features_t *f, uint32_t 
> mask)
> @@ -954,19 +951,20 @@ static int unavailable_host_feature(struct 
> model_features_t *f, uint32_t mask)
>   *
>   * This function may be called only if KVM is enabled.
>   */
> -static int kvm_check_features_against_host(x86_def_t *guest_def)
> +static int kvm_check_features_against_host(X86CPU *cpu)
>  {
> +    CPUX86State *env = &cpu->env;
>      x86_def_t host_def;
>      uint32_t mask;
>      int rv, i;
>      struct model_features_t ft[] = {
> -        {&guest_def->features, &host_def.features,
> +        {&env->cpuid_features, &host_def.features,
>              ~0, feature_name, 0x00000000},
> -        {&guest_def->ext_features, &host_def.ext_features,
> +        {&env->cpuid_ext_features, &host_def.ext_features,
>              ~CPUID_EXT_HYPERVISOR, ext_feature_name, 0x00000001},
> -        {&guest_def->ext2_features, &host_def.ext2_features,
> +        {&env->cpuid_ext2_features, &host_def.ext2_features,
>              ~PPRO_FEATURES, ext2_feature_name, 0x80000000},
> -        {&guest_def->ext3_features, &host_def.ext3_features,
> +        {&env->cpuid_ext3_features, &host_def.ext3_features,
>              ~CPUID_EXT3_SVM, ext3_feature_name, 0x80000001}};
>  
>      assert(kvm_enabled());
> @@ -981,6 +979,7 @@ static int kvm_check_features_against_host(x86_def_t 
> *guest_def)
>                  }
>      return rv;
>  }
> +#endif /* CONFIG_KVM */
>  
>  static void x86_cpuid_version_get_family(Object *obj, Visitor *v, void 
> *opaque,
>                                           const char *name, Error **errp)
> @@ -1273,7 +1272,9 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, 
> const char *name)
>          }
>      }
>      if (kvm_enabled() && name && strcmp(name, "host") == 0) {
> +#ifdef CONFIG_KVM
>          kvm_cpu_fill_host(x86_cpu_def);
> +#endif
>      } else if (!def) {
>          return -1;
>      } else {
> @@ -1428,10 +1429,6 @@ static int cpu_x86_parse_featurestr(x86_def_t 
> *x86_cpu_def, char *features)
>      x86_cpu_def->kvm_features &= ~minus_kvm_features;
>      x86_cpu_def->svm_features &= ~minus_svm_features;
>      x86_cpu_def->cpuid_7_0_ebx_features &= ~minus_7_0_ebx_features;
> -    if (check_cpuid && kvm_enabled()) {
> -        if (kvm_check_features_against_host(x86_cpu_def) && enforce_cpuid)
> -            goto error;
> -    }
>      return 0;
>  
>  error:
> @@ -2106,6 +2103,12 @@ void x86_cpu_realize(Object *obj, Error **errp)
>          env->cpuid_svm_features &= TCG_SVM_FEATURES;
>      } else {
>  #ifdef CONFIG_KVM
> +        if (check_cpuid && kvm_check_features_against_host(cpu)
> +            && enforce_cpuid) {
> +            error_setg(errp, "Host's CPU doesn't support requested 
> features");
> +            return;
> +        }
> +
>          filter_features_for_kvm(cpu);
>  #endif
>      }
> -- 
> 1.7.1
> 

-- 
Eduardo