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If the copy fails due to nonzero padding (VMM violates > the ABI), fail the entire batch. > > Convert the whole batch before issuing any of it: a malformed command is a > userspace bug, so the first illegal command fails the batch as a unit, > issuing nothing and leaving array->entry_num at zero, the same way the copy > above bails on nonzero padding. A batch that converts cleanly is issued in > full, so the op returns either a handled count with no error or zero with > an error. > > A zero-length array now returns success once the data type gets validated, > matching the documented probe behavior, rather than the -EINVAL that the > full-array copy helper would previously return. > > This also fixes two long-standing bugs: > 1) On a conversion failure the old code reported commands that it had > converted but not yet issued, so user space advanced its consumer > index past invalidations that never reached the cmdq. > 2) A zero-length array was rejected with -EINVAL, although the uAPI > documents it as a valid request that only probes the data type. > > Reviewed-by: Kevin Tian > Reviewed-by: Pranjal Shrivastava > Assisted-by: Claude:claude-opus-4-8 > Signed-off-by: Nicolin Chen > --- > .../arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 68 +++++++++++-------- > 1 file changed, 38 insertions(+), 30 deletions(-) Reviewed-by: Jason Gunthorpe Jason