Re: [PATCH v2 22/26] iommufd: Add hw_queue_init and split queue alloc paths

[Nicolin Chen]

On Thu, May 28, 2026 at 05:17:34AM +0000, Suravee Suthikulpanit wrote:
> Splitting helpers and dispatching from the ioctl keeps
> one uAPI while making the contract explicit.

Why split? Those two new ioctl functions look quite redundant..

I imagined that the original ioctl function just needed:
[...]
-	struct iommufd_access *access;
+	struct iommufd_access *access = NULL;
[...]
 	if (!viommu->ops || !viommu->ops->get_hw_queue_size ||
-	    !viommu->ops->hw_queue_init_phys) {
+	    (!viommu->ops->hw_queue_init_phys && !viommu->ops->hw_queue_init)) {
		rc = -EOPNOTSUPP;
		goto out_put_viommu;
	}
[...]
-	access = iommufd_hw_queue_alloc_phys(cmd, viommu, &base_pa);
-	if (IS_ERR(access)) {
-		rc = PTR_ERR(access);
-		goto out_put_viommu;
-	}
+	if (viommu->ops->hw_queue_init_phys) {
+		access = iommufd_hw_queue_alloc_phys(cmd, viommu, &base_pa);
+		if (IS_ERR(access)) {
+			rc = PTR_ERR(access);
+			goto out_put_viommu;
+		}
+	}
[...]
	rc = viommu->ops->hw_queue_init_phys(hw_queue, cmd->index, base_pa);
+ 	if (viommu->ops->hw_queue_init_phys)
+		rc = viommu->ops->hw_queue_init_phys(hw_queue, cmd->index,
+						     base_pa);
+	else
+		rc = viommu->ops->hw_queue_init(hw_queue, cmd->index);

and then it should work?

Nicolin