RE: [PATCH v5 08/14] iommufd/viommu: Add iommufd_viommu_report_event helper

From: Nicolin Chen nicolinc@nvidia.com Sent: Wednesday, January 8, 2025 1:10 AM

+/*

• • Typically called in driver's threaded IRQ handler.
• • The @type and @event_data must be defined in

include/uapi/linux/iommufd.h

• */

+int iommufd_viommu_report_event(struct iommufd_viommu *viommu,

• 		enum iommu_veventq_type type, void
  

*event_data,

• 		size_t data_len)
  

+{

• struct iommufd_veventq *veventq;
• struct iommufd_vevent *vevent;
• int rc = 0;
• if (!viommu)

• return -ENODEV;
  

• if (WARN_ON_ONCE(!viommu->ops || !viommu->ops-

...

supports_veventq ||

• 	 !viommu->ops->supports_veventq(type)))
  

• return -EOPNOTSUPP;
  

Hmm the driver knows which type is supported by itself before calling this helper. Why bother having the helper calling into the driver again to verify?