[PATCH v1 08/11] iommu/tegra241-cmdqv: Require exactly one Stream ID for a vSID

[Nicolin Chen]

tegra241_vintf_init_vsid() maps a guest vSID to a single physical Stream ID
taken from master->streams[0], and only warns when the device does not have
exactly one stream. A device with several streams gets only its first one
mapped, so a guest vSID invalidation cannot reach the others' ATC and IOTLB
entries; a device with none makes master->streams a ZERO_SIZE_PTR, read out
of bounds.

Reject the mapping with -EINVAL when master->num_streams is not one, rather
than warning and pressing on.

Fixes: 4dc0d12474f9 ("iommu/tegra241-cmdqv: Add user-space use support")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Nicolin Chen <nicolinc at nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
index 812cc500b4a1e..aa0568e328356 100644
--- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
+++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c
@@ -1249,7 +1249,8 @@ static int tegra241_vintf_init_vsid(struct iommufd_vdevice *vdev)
 	if (virt_sid > FIELD_MAX(VINTF_SID_MATCH_VIRT_SID))
 		return -EINVAL;
 
-	WARN_ON_ONCE(master->num_streams != 1);
+	if (master->num_streams != 1)
+		return -EINVAL;
 
 	/* Find an empty pair of SID_REPLACE and SID_MATCH */
 	sidx = ida_alloc_max(&vintf->sids, vintf->cmdqv->num_sids_per_vintf - 1,
-- 
2.43.0