[PATCH V16 05/12] drm/xe: Guard teardown paths against purged BOs

VRAM page offlining can purge BOs that are still referenced by page
tables, exec queues, and DMA-buf exports. Add xe_bo_is_purged()
guards in the teardown paths to prevent unpinning or mapping an
already-purged BO:

- xe_bo_unpin_map_no_vm(): skip unpin if purged
- xe_dma_buf_map(): return -ENOENT early if purged
- xe_exec_queue_update_run_ticks(): skip LRC timestamp read if purged
- xe_pt_destroy(): skip unpin if purged

v2(Himal):
- take dma_resv lock before calling xe_bo_is_purged()

Signed-off-by: Tejas Upadhyay <[email protected]>
---
 drivers/gpu/drm/xe/xe_bo.h         | 3 ++-
 drivers/gpu/drm/xe/xe_dma_buf.c    | 3 +++
 drivers/gpu/drm/xe/xe_exec_queue.c | 8 ++++++--
 drivers/gpu/drm/xe/xe_pt.c         | 5 ++++-
 4 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_bo.h b/drivers/gpu/drm/xe/xe_bo.h
index eede678ad303..dfcd0e57073b 100644
--- a/drivers/gpu/drm/xe/xe_bo.h
+++ b/drivers/gpu/drm/xe/xe_bo.h
@@ -364,7 +364,8 @@ static inline void xe_bo_unpin_map_no_vm(struct xe_bo *bo)
 {
 	if (likely(bo)) {
 		xe_bo_lock(bo, false);
-		xe_bo_unpin(bo);
+		if (!xe_bo_is_purged(bo))
+			xe_bo_unpin(bo);
 		xe_bo_unlock(bo);
 
 		xe_bo_put(bo);
diff --git a/drivers/gpu/drm/xe/xe_dma_buf.c b/drivers/gpu/drm/xe/xe_dma_buf.c
index bf0728838ead..5d9f1cd24b7f 100644
--- a/drivers/gpu/drm/xe/xe_dma_buf.c
+++ b/drivers/gpu/drm/xe/xe_dma_buf.c
@@ -104,6 +104,9 @@ static struct sg_table *xe_dma_buf_map(struct dma_buf_attachment *attach,
 	struct sg_table *sgt;
 	int r = 0;
 
+	if (xe_bo_is_purged(bo))
+		return ERR_PTR(-ENOENT);
+
 	if (!attach->peer2peer && !xe_bo_can_migrate(bo, XE_PL_TT))
 		return ERR_PTR(-EOPNOTSUPP);
 
diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
index d6c7f346f49b..5432710c1cfb 100644
--- a/drivers/gpu/drm/xe/xe_exec_queue.c
+++ b/drivers/gpu/drm/xe/xe_exec_queue.c
@@ -1575,8 +1575,12 @@ void xe_exec_queue_update_run_ticks(struct xe_exec_queue *q)
 	 * errors.
 	 */
 	lrc = q->lrc[0];
-	new_ts = xe_lrc_update_timestamp(lrc, &old_ts);
-	q->xef->run_ticks[q->class] += (new_ts - old_ts) * q->width;
+	xe_bo_lock(lrc->bo, false);
+	if (!xe_bo_is_purged(lrc->bo)) {
+		new_ts = xe_lrc_update_timestamp(lrc, &old_ts);
+		q->xef->run_ticks[q->class] += (new_ts - old_ts) * q->width;
+	}
+	xe_bo_unlock(lrc->bo);
 
 	drm_dev_exit(idx);
 }
diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
index 5d990c1c3740..b6575a6bada4 100644
--- a/drivers/gpu/drm/xe/xe_pt.c
+++ b/drivers/gpu/drm/xe/xe_pt.c
@@ -212,7 +212,10 @@ void xe_pt_destroy(struct xe_pt *pt, u32 flags, struct llist_head *deferred)
 		return;
 
 	XE_WARN_ON(!list_empty(&pt->bo->ttm.base.gpuva.list));
-	xe_bo_unpin(pt->bo);
+	xe_bo_lock(pt->bo, false);
+	if (!xe_bo_is_purged(pt->bo))
+		xe_bo_unpin(pt->bo);
+	xe_bo_unlock(pt->bo);
 	xe_bo_put_deferred(pt->bo, deferred);
 
 	if (pt->level > 0 && pt->num_live) {
-- 
2.52.0