xen迁移中的xc_shadow_control操作

Question

我正在研究xen迁移。我在代码中看到操作xc_shadow_control以获取脏映射，如下面的代码：

xc_shadow_control(xch, dom, XEN_DOMCTL_SHADOW_OP_PEEK, HYPERCALL_BUFFER(to_skip),
                    dinfo->p2m_size, NULL, 0, NULL)

此方法的声明如下：

    int xc_shadow_control(xc_interface *xch,
                      uint32_t domid,
                      unsigned int sop,
                      xc_hypercall_buffer_t *dirty_bitmap,
                      unsigned long pages,
                      unsigned long *mb,
                      uint32_t mode,
                      xc_shadow_op_stats_t *stats)
{
    int rc;
    DECLARE_DOMCTL;
    DECLARE_HYPERCALL_BUFFER_ARGUMENT(dirty_bitmap);

    memset(&domctl, 0, sizeof(domctl));

    domctl.cmd = XEN_DOMCTL_shadow_op;
    domctl.domain = (domid_t)domid;
    domctl.u.shadow_op.op     = sop;
    domctl.u.shadow_op.pages  = pages;
    domctl.u.shadow_op.mb     = mb ? *mb : 0;
    domctl.u.shadow_op.mode   = mode;
    if (dirty_bitmap != NULL)
        set_xen_guest_handle(domctl.u.shadow_op.dirty_bitmap,
                                dirty_bitmap);

    rc = do_domctl(xch, &domctl);

    if ( stats )
        memcpy(stats, &domctl.u.shadow_op.stats,
               sizeof(xc_shadow_op_stats_t));

    if ( mb ) 
        *mb = domctl.u.shadow_op.mb;

    return (rc == 0) ? domctl.u.shadow_op.pages : rc;
}

有人知道访客行地址与此方法返回的脏地图之间的映射关系吗？

谢谢， 王云斌