Re: [PATCH v2 3/4] iommufd: Add IOMMU_DEVICE_GET_HW_INFO

On Thu, Mar 09, 2023 at 09:50:18PM +0800, Baolu Lu wrote:

...

• if (cmd->flags || cmd->__reserved || !cmd->data_len)

• return -EOPNOTSUPP;
  

• idev = iommufd_get_device(ucmd, cmd->dev_id);
• if (IS_ERR(idev))

• return PTR_ERR(idev);
  

• ops = dev_iommu_ops(idev->dev);
• if (!ops || !ops->hw_info) {

dev_iommu_ops() will never return a NULL.

Need below check

dev->iommu && dev->iommu->iommu_dev

before dev_iommu_ops(). Perhaps something like below?

if (!dev->iommu || !dev->iommu->iommu_dev) return -EINVAL;

At this point the device has become owned through the ownership API, it absolutely has to have an iommu and an ops. No need to check anything.

Jason