On Fri, Feb 10, 2023 at 07:55:42AM +0000, Tian, Kevin wrote:
From: Liu, Yi L yi.l.liu@intel.com Sent: Thursday, February 9, 2023 12:17 PM
+int iommufd_device_get_info(struct iommufd_ucmd *ucmd) +{
- struct iommu_device_info *cmd = ucmd->cmd;
- struct iommufd_object *dev_obj;
- struct device *dev;
- const struct iommu_ops *ops;
- void *data;
- unsigned int length, data_len;
- int rc;
- if (cmd->flags || cmd->__reserved || !cmd->data_len)
return -EOPNOTSUPP;do we want !cmd->data_len being a way to check how many bytes are required in a following call to get the vendor info?
There is no reason, if the userspace doesn't have a struct large enough then it also doesn't know what the extra bytes should even be used for. No reason to read the.
+struct iommu_device_info {
- __u32 size;
- __u32 flags;
- __u32 dev_id;
- __u32 data_len;
- __aligned_u64 data_ptr;
moving forward iommu hw cap is not the only information reported via this interface, e.g. it can be also used to report pasid mode.
from this angle it's better to rename above two fields to be iommu specific, e.g.:
__u32 iommu_data_len; __aligned_u64 iommu_data_ptr;
maybe call it hw info
Jason