Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

drm/xe/vf: Fix VF CCS attach/detach race with in-flight BO moves

xe_bo_move() attaches VF CCS read/write batch buffers (BBs) to a BO after it transitions NULL/SYSTEM -> TT, and detaches them after it transitions TT -> SYSTEM. Both operations were done synchronously on the CPU immediately after building the move's copy/clear fence, without waiting for that fence to signal. This creates two races with VF migration:

- Attach happens too late relative to the copy job it is meant to protect. If the copy job is submitted before the CCS BBs are attached, a VF migration event that pauses execution mid-copy can observe partially copied CCS metadata without the attach state needed to correctly save/restore it.

- Detach happens too early relative to the copy job that moves data out of TT. The CCS BBs are torn down right after the copy fence is obtained, while the actual blit may still be in flight. A VF migration event that pauses execution mid-copy can then race the save/restore path against the still-running blit, and the CCS BBs it would need to make sense of the paused state have already been removed.

Fix both races:

- Move the attach call to before the copy/clear job is submitted, so the CCS BBs are already registered by the time the copy runs. On attach failure, unwind and bail out of the move. xe_migrate_ccs_rw_copy() now takes the destination resource explicitly, since bo->ttm.re…