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

Niklas Schnelle
2025-03-17T09:53:11Z

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().

> 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,