vgtif_offset
#define vgtif_reg(x) _MMIO(VGT_PVINFO_PAGE + vgtif_offset(x))
magic = readq(shared_area + vgtif_offset(magic));
version_major = readw(shared_area + vgtif_offset(version_major));
dev_priv->vgpu.caps = readl(shared_area + vgtif_offset(vgt_caps));