RE: [PATCH v6 07/14] iommufd/viommu: Add iommufd_viommu_report_event helper

From: Jason Gunthorpe jgg@nvidia.com Sent: Tuesday, February 18, 2025 11:36 PM

On Fri, Jan 24, 2025 at 04:30:36PM -0800, Nicolin Chen wrote:

...

+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 (WARN_ON_ONCE(!data_len || !event_data))

• return -EINVAL;
  

• down_read(&viommu->veventqs_rwsem);
• veventq = iommufd_viommu_find_veventq(viommu, type);
• if (!veventq) {

• rc = -EOPNOTSUPP;
  

• goto out_unlock_veventqs;
  

• }
• if (atomic_read(&veventq->num_events) == veventq->depth) {

• vevent = &veventq->overflow;
  

• goto out_set_header;
  

• }
• vevent = kmalloc(struct_size(vevent, event_data, data_len),

GFP_KERNEL);

...

• if (!vevent) {

• rc = -ENOMEM;
  

• goto out_unlock_veventqs;
  

This should record an overflow too

In that case probably we want to rename 'overflow' to 'lost_event' which counts lost events for whatever reasons (overflow, oom, etc.)