Re: [PATCH] target/i386: Add kvm_get_one_msr helper

[Yang, Weijiang]

On 1/28/2022 6:55 PM, Paolo Bonzini wrote:
> On 1/27/22 16:58, Yang Weijiang wrote:
> > @@ -135,6 +135,7 @@ static struct kvm_msr_list *kvm_feature_msrs;
> >     #define BUS_LOCK_SLICE_TIME 1000000000ULL /* ns */
> >   static RateLimit bus_lock_ratelimit_ctrl;
> > +static int kvm_get_one_msr(X86CPU *cpu, int index, uint64_t *value);
> >     int kvm_has_pit_state2(void)
> >   {
>
> ...
>
> > @@ -2734,6 +2721,25 @@ static int kvm_put_one_msr(X86CPU *cpu, int 
> > index, uint64_t value)
> >       return kvm_vcpu_ioctl(CPU(cpu), KVM_SET_MSRS, cpu->kvm_msr_buf);
> >   }
> >   +static int kvm_get_one_msr(X86CPU *cpu, int index, uint64_t *value)
> > +{
> > +    int ret;
> > +    struct {
> > +        struct kvm_msrs info;
> > +        struct kvm_msr_entry entries[1];
> > +    } msr_data = {
> > +        .info.nmsrs = 1,
> > +        .entries[0].index = index,
> > +    };
> > +
> > +    ret = kvm_vcpu_ioctl(CPU(cpu), KVM_GET_MSRS, &msr_data);
> > +    if (ret < 0) {
> > +        return ret;
> > +    }
> > +    assert(ret == 1);
> > +    *value = msr_data.entries[0].data;
> > +    return ret;
> > +}
> >   void kvm_put_apicbase(X86CPU *cpu, uint64_t value)
> >   {
> >       int ret;
>
> The patch is a good idea, but you can put the function before the 
> uses.  This way there will be no need for a forward declaration, either.

Thanks Paolo!

Is v2 version required for this?

> Thanks,
>
> Paolo