Re: [PATCH v4 07/18] iommufd: Add IOMMU_HWPT_GET_DIRTY_IOVA

[Joao Martins <joao.m.martins@xxxxxxxxxx>]

On 18/10/2023 21:27, Joao Martins wrote:
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index 9e1721e38819..efeb12c1aaeb 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -48,6 +48,7 @@ enum {
>  	IOMMUFD_CMD_HWPT_ALLOC,
>  	IOMMUFD_CMD_GET_HW_INFO,
>  	IOMMUFD_CMD_HWPT_SET_DIRTY,
> +	IOMMUFD_CMD_HWPT_GET_DIRTY_IOVA,
>  };
>  
>  /**
> @@ -479,4 +480,31 @@ struct iommu_hwpt_set_dirty {
>  	__u32 __reserved;
>  };
>  #define IOMMU_HWPT_SET_DIRTY _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_SET_DIRTY)
> +
> +/**
> + * struct iommu_hwpt_get_dirty_iova - ioctl(IOMMU_HWPT_GET_DIRTY_IOVA)
> + * @size: sizeof(struct iommu_hwpt_get_dirty_iova)
> + * @hwpt_id: HW pagetable ID that represents the IOMMU domain.
> + * @flags: Flags to control dirty tracking status.
> + * @iova: base IOVA of the bitmap first bit
> + * @length: IOVA range size
> + * @page_size: page size granularity of each bit in the bitmap
> + * @data: bitmap where to set the dirty bits. The bitmap bits each
> + * represent a page_size which you deviate from an arbitrary iova.
> + * Checking a given IOVA is dirty:
> + *
> + *  data[(iova / page_size) / 64] & (1ULL << (iova % 64))
> + */
> +struct iommu_hwpt_get_dirty_iova {
> +	__u32 size;
> +	__u32 hwpt_id;
> +	__u32 flags;
> +	__u32 __reserved;
> +	__aligned_u64 iova;
> +	__aligned_u64 length;
> +	__aligned_u64 page_size;
> +	__aligned_u64 *data;
> +};
> +#define IOMMU_HWPT_GET_DIRTY_IOVA _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_GET_DIRTY_IOVA)
> +
>  #endif

I added this extra chunk:

diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 6b26045f6577..3349347cb766 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -502,7 +502,7 @@ struct iommu_hwpt_set_dirty {
  * struct iommu_hwpt_get_dirty_iova - ioctl(IOMMU_HWPT_GET_DIRTY_IOVA)
  * @size: sizeof(struct iommu_hwpt_get_dirty_iova)
  * @hwpt_id: HW pagetable ID that represents the IOMMU domain.
- * @flags: Flags to control dirty tracking status.
+ * @flags: Flags to control the fetching of dirty IOVAs.
  * @iova: base IOVA of the bitmap first bit
  * @length: IOVA range size
  * @page_size: page size granularity of each bit in the bitmap
@@ -511,6 +511,10 @@ struct iommu_hwpt_set_dirty {
  * Checking a given IOVA is dirty:
  *
  *  data[(iova / page_size) / 64] & (1ULL << (iova % 64))
+ *
+ * Walk the IOMMU pagetables for a given IOVA range to return a bitmap
+ * with the dirty IOVAs. In doing so it will also by default clear any
+ * dirty bit metadata set in the IOPTE.
  */
 struct iommu_hwpt_get_dirty_iova {
        __u32 size;