Re: [PATCH v7 03/17] iommu: generalize the batched sync after map interface

Leon Romanovsky
2025-03-17T13:44:43Z

On Mon, Mar 17, 2025 at 10:52:11AM +0100, Niklas Schnelle wrote:
> On Wed, 2025-02-05 at 16:40 +0200, Leon Romanovsky wrote:
> > From: Christoph Hellwig <hch@lst.de>
> >
> > For the upcoming IOVA-based DMA API we want to use the interface batch the
> > sync after mapping multiple entries from dma-iommu without having a
> > scatterlist.
> >
> > For that move more sanity checks from the callers into __iommu_map and
> > make that function available outside of iommu.c as iommu_map_nosync.
> >
> > Add a wrapper for the map_sync as iommu_sync_map so that callers don't
> > need to poke into the methods directly.
> >
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > Acked-by: Will Deacon <will@kernel.org>
> > Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> > ---
> > drivers/iommu/iommu.c | 65 +++++++++++++++++++------------------------
> > include/linux/iommu.h | 4 +++
> > 2 files changed, 33 insertions(+), 36 deletions(-)
> >
> >
> --- snip ---
> > +
> > return mapped;
> >
> > out_err:
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > index 38c65e92ecd0..7ae9aa3a1894 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -857,6 +857,10 @@ extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
> > extern struct iommu_domain *iommu_get_dma_domain(struct device *dev);
> > extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
> > phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
> > +int iommu_map_nosync(struct iommu_domain *domain, unsigned long iova,
> > + phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
> > +int iommu_sync_map(struct iommu_domain *domain, unsigned long iova,
> > + size_t size);
>
> There are two different word orders in the function names.
> iommu_sync_map() vs iommu_map_nosync(). I'd prefer to be consistent
> with e.g. iommu_map_sync() vs iommu_map_nosync().

The naming came from refactoring different functions, one was simple *_map() and
another was iotlb_*_sync(), but yes we can name it consistently.

Thanks

>
> > extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
> > size_t size);
> > extern size_t iommu_unmap_fast(struct iommu_domain *domain,
>