RE: [PATCH v3 02/17] iommu: Add nested domain support

[Liu, Yi L]

> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Thursday, August 3, 2023 10:37 AM
> 
> On Fri, Jul 28, 2023 at 01:59:28PM -0300, Jason Gunthorpe wrote:
> > On Mon, Jul 24, 2023 at 04:03:51AM -0700, Yi Liu wrote:
> >
> > > @@ -350,6 +354,10 @@ struct iommu_ops {
> > >   * @iotlb_sync_map: Sync mappings created recently using @map to the hardware
> > >   * @iotlb_sync: Flush all queued ranges from the hardware TLBs and empty flush
> > >   *            queue
> > > + * @cache_invalidate_user: Flush hardware TLBs caching user space IO mappings
> > > + * @cache_invalidate_user_data_len: Defined length of input user data for the
> > > + *                                  cache_invalidate_user op, being sizeof the
> > > + *                                  structure in include/uapi/linux/iommufd.h
> > >   * @iova_to_phys: translate iova to physical address
> > >   * @enforce_cache_coherency: Prevent any kind of DMA from bypassing
> IOMMU_CACHE,
> > >   *                           including no-snoop TLPs on PCIe or other platform
> > > @@ -379,6 +387,9 @@ 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,
> > > +				     void *user_data);
> >
> > If we are doing const unions, then this void * should also be a const
> > union.
> 
> Unlike iommu_domain_user_data is a union on its own, all invalidate
> user data structures are added to union ucmd_buffer. It feels a bit
> weird to cross reference "union ucmd_buffer" and to pass the naming
> "ucmd_buffer" in this cache_invalidate_user.
> 
> Any suggestion?

I think we can have a union like iommu_user_cache_invalidate, every new
data structures should be put in this union, and this union is put in the
ucmd_buffer.

Regards,
Yi Liu