Re: [Qemu-devel] [PATCH v4 02/18] target-i386: Simplify reporting of unavailable features

[Andreas Färber]

Am 30.04.2014 18:48, schrieb Eduardo Habkost:
> Instead of checking and calling unavailable_host_feature() once for each
> bit, simply call the function (now renamed to
> report_unavailable_features()) once for each feature word.
> 
> Signed-off-by: Eduardo Habkost <address@hidden>
> ---
> Changes v1 -> v2:
>  * Rebase to latest qom-cpu (commit 90c5d39c)
> Changes v2 -> v3:
>  * Trivial rebase after QEMU 2.0 (onto commit 2d03b49)
> ---
>  target-i386/cpu.c | 16 +++++++---------
>  1 file changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 7ec706f..9cd0039 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1236,11 +1236,11 @@ static const TypeInfo host_x86_cpu_type_info = {
>  
>  #endif
>  
> -static int unavailable_host_feature(FeatureWordInfo *f, uint32_t mask)
> +static int report_unavailable_features(FeatureWordInfo *f, uint32_t mask)
>  {
>      int i;
>  
> -    for (i = 0; i < 32; ++i)
> +    for (i = 0; i < 32; ++i) {
>          if (1 << i & mask) {
>              const char *reg = get_register_name_32(f->cpuid_reg);
>              assert(reg);
> @@ -1249,8 +1249,8 @@ static int unavailable_host_feature(FeatureWordInfo *f, 
> uint32_t mask)
>                  f->cpuid_eax, reg,
>                  f->feat_names[i] ? "." : "",
>                  f->feat_names[i] ? f->feat_names[i] : "", i);
> -            break;
>          }
> +    }
>      return 0;
>  }
>  
> @@ -1274,12 +1274,10 @@ static int kvm_check_features_against_host(KVMState 
> *s, X86CPU *cpu)
>          uint32_t host_feat = kvm_arch_get_supported_cpuid(s, wi->cpuid_eax,
>                                                               wi->cpuid_ecx,
>                                                               wi->cpuid_reg);
> -        uint32_t mask;
> -        for (mask = 1; mask; mask <<= 1) {
> -            if (guest_feat & mask && !(host_feat & mask)) {
> -                unavailable_host_feature(wi, mask);
> -                rv = 1;
> -            }
> +        uint32_t unavailable_features = guest_feat & ~host_feat;
> +        if (unavailable_features) {
> +            report_unavailable_features(wi, unavailable_features);
> +            rv = 1;
>          }
>      }
>      return rv;

Both before and after your patch the return value is never checked.
Shall we/I change it to void?

Regards,
Andreas

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 3c4f327..d095c7d 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1236,7 +1236,7 @@ static const TypeInfo host_x86_cpu_type_info = {

 #endif

-static int report_unavailable_features(FeatureWordInfo *f, uint32_t mask)
+static void report_unavailable_features(FeatureWordInfo *f, uint32_t mask)
 {
     int i;

@@ -1251,7 +1251,6 @@ static int
report_unavailable_features(FeatureWordInfo *f, uint32_t mask)
                 f->feat_names[i] ? f->feat_names[i] : "", i);
         }
     }
-    return 0;
 }

 /* Check if all requested cpu flags are making their way to the guest

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