Re: [PATCH v6 3/4] iommufd: Add IOMMU_GET_HW_INFO

On Wed, Aug 09, 2023 at 06:16:19PM +0800, Baolu Lu wrote:

On 2023/8/8 23:35, Yi Liu wrote:

...

+static int iommufd_fill_hw_info(struct device *dev, void __user *user_ptr,

• 		unsigned int *length, u32 *type)
  

+{

• const struct iommu_ops *ops;
• unsigned int data_len;
• void *data;
• int rc = 0;
• ops = dev_iommu_ops(dev);
• if (!ops->hw_info) {

• *length = 0;
  

• *type = IOMMU_HW_INFO_TYPE_NONE;
  

• return 0;
  

• }
• data = ops->hw_info(dev, &data_len, type);
• if (IS_ERR(data))

• return PTR_ERR(data);
  

• /*

• * drivers that have hw_info callback should have a unique
  

• * iommu_hw_info_type.
  

• */
  

• if (WARN_ON_ONCE(*type == IOMMU_HW_INFO_TYPE_NONE)) {

• rc = -ENODEV;
  

• goto err_free;
  

• }
• *length = min(*length, data_len);
• if (copy_to_user(user_ptr, data, *length)) {

copy_to_user() returns the number of bytes that were successfully copied, right?

It returns length on failure and 0 on success

Jason