xgetbv
xgetbv(0, &eax, NULL);
xgetbv(0, &eax, NULL);
if (xgetbv(0) & XFEATURE_AVX512) {
} else if (xgetbv(0) & XFEATURE_AVX) {
vcpu->vc_gueststate.vg_xcr0 = xgetbv(0);
uint64_t xcr0 = xgetbv(0x0);