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

[Paolo Bonzini <pbonzini@redhat.com>]

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