Re: [PATCH 1/9] iommu/pages: Add support for a incoherent IOMMU page walker

[Baolu Lu <baolu.lu@linux.intel.com>]

On 7/17/2025 3:57 AM, Jason Gunthorpe wrote:
> @@ -98,4 +101,36 @@ static inline void *iommu_alloc_pages_sz(gfp_t gfp, size_t size)
>   	return iommu_alloc_pages_node_sz(NUMA_NO_NODE, gfp, size);
>   }
>   
> -#endif	/* __IOMMU_PAGES_H */
> +int iommu_pages_start_incoherent(void *virt, struct device *dma_dev);
> +int iommu_pages_start_incoherent_list(struct iommu_pages_list *list,
> +                                      struct device *dma_dev);
> +
> +#ifdef CONFIG_X86
> +#include <asm/cacheflush.h>
> +
> +static inline void iommu_pages_flush_incoherent(struct device *dma_dev,
> +						void *virt, size_t offset,
> +						size_t len)
> +{
> +	clflush_cache_range(virt + offset, len);
> +}
> +static inline void
> +iommu_pages_stop_incoherent_list(struct iommu_pages_list *list,
> +				 struct device *dma_dev)
> +{

Do we need to clear iopt->incoherent for X86, given that
iopt->incoherent is set in the start path? If no need, can you please
add a comment to explain it?

> +}
> +#else
> +#include <linux/dma-mapping.h>
> +
> +static inline void iommu_pages_flush_incoherent(struct device *dma_dev,
> +						void *virt, size_t offset,
> +						size_t len)
> +{
> +	dma_sync_single_for_device(dma_dev, (uintptr_t)virt + offset, len,
> +				   DMA_TO_DEVICE);
> +}
> +void iommu_pages_stop_incoherent_list(struct iommu_pages_list *list,
> +                                      struct device *dma_dev);
> +#endif
> +
> +#endif /* __IOMMU_PAGES_H */

Thanks,
baolu