HV_MSR_HYPERCALL_AVAILABLE
if (!(eax & HV_MSR_HYPERCALL_AVAILABLE)) {
HV_MSR_HYPERCALL_AVAILABLE;
ent->eax |= HV_MSR_HYPERCALL_AVAILABLE;
vcpu_set_cpuid_feature(vcpu, HV_MSR_HYPERCALL_AVAILABLE);
vcpu_set_cpuid_feature(vcpu, HV_MSR_HYPERCALL_AVAILABLE);