Re: [PATCH 3/9] iommupt: Use the incoherent start/stop functions for PT_FEAT_DMA_INCOHERENT

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Aug 15, 2025 at 11:35:46AM +0000, Tian, Kevin wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Thursday, July 17, 2025 3:58 AM
> > 
> > @@ -57,6 +57,12 @@ struct pt_iommu {
> >  	 * table walkers.
> >  	 */
> >  	int nid;
> > +
> > +	/**
> > +	 * @iommu_device - Device pointer used for any DMA cache flushing
> > when
> > +	 * PT_FEAT_DMA_INCOHERENT.
> > +	 */
> > +	struct device *iommu_device;
> >  };
> > 
> 
> It may be worth pointing out that a page table could be used
> by multiple IOMMUs but we expect all IOMMUs sharing the
> page table to have the same coherency attribute so here just
> record the pointer to the 1st connected iommu device.

	/**
	 * @iommu_device - Device pointer used for any DMA cache flushing when
	 * PT_FEAT_DMA_INCOHERENT. This is the iommu device that created the
	 * page table which must have dma ops that perform cache flushing.
	 */

?

Thanks,
Jason