vmmdev_hgcm_pagelist
*extra += offsetof(struct vmmdev_hgcm_pagelist, pages[page_count]);
struct vmmdev_hgcm_pagelist *dst_pg_lst;
*off_extra += offsetof(struct vmmdev_hgcm_pagelist, pages[page_count]);
VMMDEV_ASSERT_SIZE(vmmdev_hgcm_pagelist, 4 + 2 + 2 + 8);