Local GPU data disclosure via omitted cache flush

Information disclosure in the drm/xe driver in Linux allows local users to read stale GPU data after graphics memory reuse. emit_render_cache_flush() requests an L2/HDC flush but omits the untyped L1 dataport-cache flush, leaving reclaimed or evicted memory contents resident. Exploitation requires Xe2-or-later graphics hardware, RCS or CCS batch activity, and subsequent memory reuse; the bounded consequence is disclosure of prior GPU data.