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

[Tian, Kevin]

> From: Jason Gunthorpe <jgg at 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.)