Re: [Qemu-devel] [PATCH v4 12/18] target-i386: Support check/enforce flags in TCG mode, too

["Andreas Färber" <afaerber@suse.de>]

Am 30.04.2014 18:48, schrieb Eduardo Habkost:
> If enforce/check is specified in TCG mode, QEMU will ensure all CPU
> features are supported by TCG, so no CPU feature is silently disabled.
> 
> Reviewed-by: Richard Henderson <rth@twiddle.net>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> Changes v1 -> v2:
>  * Trivial rebase to latest qom-cpu (commit 90c5d39c)
>    (Reviewed-by line kept)
> Changes v2 -> v3:
>  * Trivial rebase after QEMU 2.0 (onto commit 2d03b49)
>    (Reviewed-by line kept)
> ---
>  target-i386/cpu.c | 34 ++++++++++++++++------------------
>  1 file changed, 16 insertions(+), 18 deletions(-)
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index b2e30ca..53b5038 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1265,8 +1265,9 @@ static int report_unavailable_features(FeatureWord w, uint32_t mask)
>          if (1 << i & mask) {
>              const char *reg = get_register_name_32(f->cpuid_reg);
>              assert(reg);
> -            fprintf(stderr, "warning: host doesn't support requested feature: "
> +            fprintf(stderr, "warning: %s doesn't support requested feature: "
>                  "CPUID.%02XH:%s%s%s [bit %d]\n",
> +                kvm_enabled() ? "host" : "TCG",
>                  f->cpuid_eax, reg,
>                  f->feat_names[i] ? "." : "",
>                  f->feat_names[i] ? f->feat_names[i] : "", i);
> @@ -1826,17 +1827,18 @@ CpuDefinitionInfoList *arch_query_cpu_definitions(Error **errp)
>  static uint32_t x86_cpu_get_supported_feature_word(FeatureWord w)
>  {
>      FeatureWordInfo *wi = &feature_word_info[w];
> -    assert(kvm_enabled());
> -    return kvm_arch_get_supported_cpuid(kvm_state, wi->cpuid_eax,
> -                                                   wi->cpuid_ecx,
> -                                                   wi->cpuid_reg);
> +    if (kvm_enabled()) {
> +        return kvm_arch_get_supported_cpuid(kvm_state, wi->cpuid_eax,
> +                                                       wi->cpuid_ecx,
> +                                                       wi->cpuid_reg);
> +    } else {
> +        return wi->tcg_features;
> +    }
>  }

This function is called unconditionally now, so apply the following?

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 48ba1d8..112b437 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1839,8 +1839,10 @@ static uint32_t
x86_cpu_get_supported_feature_word(FeatureWord w)
         return kvm_arch_get_supported_cpuid(kvm_state, wi->cpuid_eax,
                                                        wi->cpuid_ecx,
                                                        wi->cpuid_reg);
-    } else {
+    } else if (tcg_enabled()) {
         return wi->tcg_features;
+    } else {
+        return UINT32_MAX;
     }
 }


Not sure what to do about the warning message. It wouldn't occur though
due to the suggested mask, so we could just ignore it for now.

Regards,
Andreas

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