MSR_LSTAR
wrmsr(MSR_LSTAR, cpu_meltdown ? (uint64_t)Xsyscall_meltdown :
svm_setmsrbrw(vcpu, MSR_LSTAR);
msr_store[VCPU_HOST_REGS_LSTAR].vms_index = MSR_LSTAR;
msr_store[VCPU_HOST_REGS_LSTAR].vms_data = rdmsr(MSR_LSTAR);
msr_store[VCPU_REGS_LSTAR].vms_index = MSR_LSTAR;
vmx_setmsrbrw(vcpu, MSR_LSTAR);
case MSR_LSTAR: return "LSTAR";