Re: [PATCH v6 1/6] iommu: Add cache_invalidate_user op

[Nicolin Chen <nicolinc@nvidia.com>]

On Wed, Dec 06, 2023 at 02:32:09PM -0400, Jason Gunthorpe wrote:
> On Fri, Nov 17, 2023 at 05:07:12AM -0800, Yi Liu wrote:
 
> > @@ -465,6 +492,9 @@ struct iommu_domain_ops {
> >  			      size_t size);
> >  	void (*iotlb_sync)(struct iommu_domain *domain,
> >  			   struct iommu_iotlb_gather *iotlb_gather);
> > +	int (*cache_invalidate_user)(struct iommu_domain *domain,
> > +				     struct iommu_user_data_array *array,
> > +				     u32 *error_code);
> 
> Regarding the other conversation I worry a u32 error_code is too small.
> 
> Unfortunately there is no obvious place to put something better so if
> we reach it we will have to add more error_code space via normal
> extension.
> 
> Maybe expand this to u64? That is 64 bits of error register data and
> the consumer index. It should do for SMMUv3 at least?

I think Yi is moving the error_code to the entry data structure,
where we can even define a list of error_codes as a driver data
needs. So, I assume this u32 pointer would be gone too.

Thanks
Nicolin