Re: [Qemu-devel] [PATCH] target-i386: adds PV_DEDICATED hint CPUID feature bit

[Eduardo Habkost]

On Fri, Feb 09, 2018 at 09:41:41AM +0100, Paolo Bonzini wrote:
> On 08/02/2018 19:12, Eduardo Habkost wrote:
> > On Thu, Feb 08, 2018 at 05:44:20PM +0800, Wanpeng Li wrote:
> >> From: Wanpeng Li <address@hidden>
> >>
> >> Add PV_DEDICATED hint cpuid feature bit.
> >>
> > [...]
> >> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> >> index d70954b..cf48931 100644
> >> --- a/target/i386/cpu.c
> >> +++ b/target/i386/cpu.c
> >> @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu)
> >>              x86_cpu_get_supported_feature_word(w, false);
> >>          uint32_t requested_features = env->features[w];
> >>          env->features[w] &= host_feat;
> >> +        if (cpu->pv_dedicated && (w == FEAT_KVM)) {
> >> +            env->features[w] |= CPUID_PV_DEDICATED;
> >> +        }
> > 
> > Why do this trick here instead of just adding "pv-dedicated" to
> > feature_word_info[FEAT_KVM].feat_names?
> 
> I think because it can be added independent of KVM_GET_SUPPORTED_CPUID.

If QEMU knows it can be enabled if outside GET_SUPPORTED_CPUID,
kvm_arch_get_supported_cpuid() can return it as supported.

-- 
Eduardo