Re: [PATCH v3] vfio/type1: Adopt fast IOTLB flush interface when unmap IOVAs

[Suravee Suthikulpanit]

Alex/Joerg,

On 1/24/18 5:04 AM, Alex Williamson wrote:
> > +static size_t try_unmap_unpin_fast(struct vfio_domain *domain, dma_addr_t iova,
> > +				   size_t len, phys_addr_t phys,
> > +				   struct list_head *unmapped_regions)
> > +{
> > +	struct vfio_regions *entry;
> > +	size_t unmapped;
> > +
> > +	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
> > +	if (!entry)
> > +		return -ENOMEM;
> size_t is unsigned, so pushing -ENOMEM out though this unsigned
> function and the callee interpreting it as unsigned, means we're going
> to see this as a very large unmap, not an error condition.  Looks like
> the IOMMU API has problems in this space too, ex. iommu_unmap(), Joerg?


I can clean up the APIs to use ssize_t, where it can return errors.

Suravee