[RFC PATCH 2/5] iommu: Add an unmap_pages() op for IOMMU drivers

[Lu Baolu]

On 3/31/21 11:00 AM, Isaac J. Manjarres wrote:
> Add a callback for IOMMU drivers to provide a path for the
> IOMMU framework to call into an IOMMU driver, which can call
> into the io-pgtable code, to unmap a virtually contiguous
> range of pages of the same size.
> 
> For IOMMU drivers that do not specify an unmap_pages() callback,
> the existing logic of unmapping memory one page block at a time
> will be used.
> 
> Signed-off-by: Isaac J. Manjarres <isaacm at codeaurora.org>
> Suggested-by: Will Deacon <will at kernel.org>
> ---
>   include/linux/iommu.h | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 5e7fe519430a..9cf81242581a 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -193,6 +193,7 @@ struct iommu_iotlb_gather {
>    * @detach_dev: detach device from an iommu domain
>    * @map: map a physically contiguous memory region to an iommu domain
>    * @unmap: unmap a physically contiguous memory region from an iommu domain
> + * @unmap_pages: unmap a number of pages of the same size from an iommu domain
>    * @flush_iotlb_all: Synchronously flush all hardware TLBs for this domain
>    * @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
> @@ -245,6 +246,9 @@ struct iommu_ops {
>   		   phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
>   	size_t (*unmap)(struct iommu_domain *domain, unsigned long iova,
>   		     size_t size, struct iommu_iotlb_gather *iotlb_gather);
> +	size_t (*unmap_pages)(struct iommu_domain *domain, unsigned long iova,
> +			      size_t pgsize, size_t pgcount,
> +			      struct iommu_iotlb_gather *iotlb_gather);

Is it possible to add an equivalent map_pages() callback?

>   	void (*flush_iotlb_all)(struct iommu_domain *domain);
>   	void (*iotlb_sync_map)(struct iommu_domain *domain, unsigned long iova,
>   			       size_t size);
> 

Best regards,
baolu