Re: [PATCH v2 4/5] iommu/virtio: Pass end address to viommu_add_mapping()

[Jean-Philippe Brucker]

On Sat, Nov 27, 2021 at 06:09:56PM -0500, Michael S. Tsirkin wrote:
> > > -static int viommu_add_mapping(struct viommu_domain *vdomain, unsigned long iova,
> > > -			      phys_addr_t paddr, size_t size, u32 flags)
> > > +static int viommu_add_mapping(struct viommu_domain *vdomain, u64 iova, u64 end,
> > > +			      phys_addr_t paddr, u32 flags)
> > >  {
> > >  	unsigned long irqflags;
> > >  	struct viommu_mapping *mapping;
> 
> I am worried that API changes like that will cause subtle
> bugs since types of arguments change but not their
> number. If we forgot to update some callers it will all be messed up.
> 
> How about passing struct Range instead?

I gave struct range a try but it looks messier overall since it would only
be used to pass arguments. I think the update is safe enough because there
is one caller for viommu_add_mapping() and two for viommu_del_mappings(),
at the moment.

Thanks,
Jean