From: Leon Romanovsky <leonro@nvidia.com>

Add kernel-doc section for iommu_unmap and iommu_unmap_fast to document
existing limitation of underlying functions which can't split individual
ranges.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/iommu/iommu.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index ec75d14497bf..9eb7c7d7aa70 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2590,6 +2590,24 @@ size_t iommu_unmap(struct iommu_domain *domain,
 }
 EXPORT_SYMBOL_GPL(iommu_unmap);
 
+/**
+ * iommu_unmap_fast() - Remove mappings from a range of IOVA without IOTLB sync
+ * @domain: Domain to manipulate
+ * @iova: IO virtual address to start
+ * @size: Length of the range starting from @iova
+ * @iotlb_gather: range information for a pending IOTLB flush
+ *
+ * iommu_unmap_fast() will remove a translation created by iommu_map(). It cannot
+ * subdivide a mapping created by iommu_map(), so it should be called with IOVA
+ * ranges that match what was passed to iommu_map(). The range can aggregate
+ * contiguous iommu_map() calls so long as no individual range is split.
+ *
+ * Basicly iommu_unmap_fast() as the same as iommu_unmap() but for callers
+ * which manage IOTLB flush range externaly to perform batched sync.
+ *
+ * Returns: Number of bytes of IOVA unmapped. iova + res will be the point
+ * unmapping stopped.
+ */
 size_t iommu_unmap_fast(struct iommu_domain *domain,
 			unsigned long iova, size_t size,
 			struct iommu_iotlb_gather *iotlb_gather)
-- 
2.47.0

On Thu, Dec 05, 2024 at 03:21:03PM +0200, Leon Romanovsky wrote:
> +/**
> + * iommu_unmap_fast() - Remove mappings from a range of IOVA without IOTLB sync
> + * @domain: Domain to manipulate
> + * @iova: IO virtual address to start
> + * @size: Length of the range starting from @iova
> + * @iotlb_gather: range information for a pending IOTLB flush
> + *
> + * iommu_unmap_fast() will remove a translation created by iommu_map(). It cannot

Please avoid the overly long line here.

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

On Thu, Dec 05, 2024 at 03:21:03PM +0200, Leon Romanovsky wrote:
> From: Leon Romanovsky <leonro@nvidia.com>
> 
> Add kernel-doc section for iommu_unmap and iommu_unmap_fast to document
> existing limitation of underlying functions which can't split individual
> ranges.
> 
> Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
>  drivers/iommu/iommu.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index ec75d14497bf..9eb7c7d7aa70 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2590,6 +2590,24 @@ size_t iommu_unmap(struct iommu_domain *domain,
>  }
>  EXPORT_SYMBOL_GPL(iommu_unmap);
>  
> +/**
> + * iommu_unmap_fast() - Remove mappings from a range of IOVA without IOTLB sync
> + * @domain: Domain to manipulate
> + * @iova: IO virtual address to start
> + * @size: Length of the range starting from @iova
> + * @iotlb_gather: range information for a pending IOTLB flush
> + *
> + * iommu_unmap_fast() will remove a translation created by iommu_map(). It cannot
> + * subdivide a mapping created by iommu_map(), so it should be called with IOVA
> + * ranges that match what was passed to iommu_map(). The range can aggregate
> + * contiguous iommu_map() calls so long as no individual range is split.
> + *
> + * Basicly iommu_unmap_fast() as the same as iommu_unmap() but for callers

Typo: s/Basicly/Basically/
Typo: s/as the same/is the same/

> + * which manage IOTLB flush range externaly to perform batched sync.

Grammar: s/manage IOTLB flush range/manage the IOTLB flushing/
Typo: s/externaly/externally/
Grammar: s/to perform batched sync/to perform a batched sync/

With those:

Acked-by: Will Deacon <will@kernel.org>

Thank you for doing this!

Will