Commit da857c9a authored Mar 26, 2026 by Arvind Yadav Committed by Matthew Brost Mar 26, 2026

drm/xe/dma_buf: Block export of DONTNEED/purged BOs



Don't allow exporting BOs marked DONTNEED or PURGED as dma-bufs.
DONTNEED BOs can have their contents discarded at any time, making
the exported dma-buf unusable for external devices. PURGED BOs have
no backing store and are permanently invalid.

Return -EBUSY for DONTNEED BOs (temporary purgeable state) and
-EINVAL for purged BOs (permanent, no backing store).

The export path now checks the BO's purgeable state before creating
the dma-buf, preventing external devices from accessing memory that
may be purged at any time.

Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20260326130843.3545241-10-arvind.yadav@intel.com

parent 975bc3ea

drivers/gpu/drm/xe/xe_dma_buf.c

+24 −0

Original line number	Diff line number	Diff line
		@@ -223,6 +223,26 @@ struct dma_buf xe_gem_prime_export(struct drm_gem_object obj, int flags)
		if (bo->vm)
		return ERR_PTR(-EPERM);

		/*
		* Reject exporting purgeable BOs. DONTNEED BOs can be purged
		* at any time, making the exported dma-buf unusable. Purged BOs
		* have no backing store and are permanently invalid.
		*/
		ret = xe_bo_lock(bo, true);
		if (ret)
		return ERR_PTR(ret);

		if (xe_bo_madv_is_dontneed(bo)) {
		ret = -EBUSY;
		goto out_unlock;
		}

		if (xe_bo_is_purged(bo)) {
		ret = -EINVAL;
		goto out_unlock;
		}
		xe_bo_unlock(bo);

		ret = ttm_bo_setup_export(&bo->ttm, &ctx);
		if (ret)
		return ERR_PTR(ret);
		@@ -232,6 +252,10 @@ struct dma_buf xe_gem_prime_export(struct drm_gem_object obj, int flags)
		buf->ops = &xe_dmabuf_ops;

		return buf;

		out_unlock:
		xe_bo_unlock(bo);
		return ERR_PTR(ret);
		}

		static struct drm_gem_object *