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

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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
This commit is contained in:
Arvind Yadav 2026-03-26 18:38:35 +05:30 committed by Matthew Brost
parent 975bc3ea4c
commit da857c9a48
1 changed files with 24 additions and 0 deletions
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24
drivers/gpu/drm/xe/xe_dma_buf.c
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@ -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 *