Applied this to drm-misc-fixes.
On 8/19/26 15:44, Taimuraz Kaitmazov wrote:
SYNC_BO clflushes an imported BO's scatterlist. An importer may not do
that: the memory belongs to the exporter, and dma-buf gives the importer
no interface to ask for maintenance on it. Refuse the request instead.
is_import_bo() is (obj)->attach, which covers more than foreign buffers.
A userptr BO arrives through a ubuf, and on a carveout device every share
BO and the device heap arrive through a cbuf, so SYNC_BO answers
-EOPNOTSUPP for those too, including the AMDXDNA_BO_DEV path that flushes
through its heap.
Only the ubuf case gives up maintenance it was getting: on a 64 MiB
userptr BO a 4 KiB sync and a full sync both cost 659 us, this arm having
ignored the range. amdxdna_cbuf_map() fills in only the DMA address and
length, so drm_clflush_sg() already walks zero pages on carveout memory.
Userspace maintains these through the mapping it already holds, as XRT's
buffer::sync() does unless it is told to sync through the driver.
Suggested-by: Lizhi Hou <[email protected]>
Signed-off-by: Taimuraz Kaitmazov <[email protected]>
Reviewed-by: Lizhi Hou <[email protected]>
---
drivers/accel/amdxdna/amdxdna_gem.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/accel/amdxdna/amdxdna_gem.c
b/drivers/accel/amdxdna/amdxdna_gem.c
index 0e0f844526ca..4be5298d1062 100644
--- a/drivers/accel/amdxdna/amdxdna_gem.c
+++ b/drivers/accel/amdxdna/amdxdna_gem.c
@@ -1224,6 +1224,9 @@ static int amdxdna_flush_bo(struct amdxdna_gem_obj *abo,
u64 offset, u64 size)
{
u64 end;
+ if (is_import_bo(abo))
+ return -EOPNOTSUPP;
+
if (offset >= abo->mem.size)
return -EINVAL;
@@ -1234,9 +1237,7 @@ static int amdxdna_flush_bo(struct amdxdna_gem_obj *abo, u64 offset, u64 size)
if (!size)
return 0;
- if (is_import_bo(abo))
- drm_clflush_sg(abo->base.sgt);
- else if (amdxdna_gem_vmap(abo))
+ if (amdxdna_gem_vmap(abo))
drm_clflush_virt_range(amdxdna_gem_vmap(abo) + offset, size);
else if (abo->base.pages)
drm_clflush_pages(abo->base.pages, abo->mem.size >> PAGE_SHIFT);
