On Sun, Mar 20, 2022 at 02:40:21PM +0800, Lu Baolu wrote:
> Add a new iommu domain type IOMMU_DOMAIN_SVA to represent an I/O page
> table which is shared from CPU host VA. Add a sva_cookie field in the
> iommu_domain structure to save the mm_struct which represent the CPU
> memory page table.
> 
> Signed-off-by: Lu Baolu <[email protected]>
>  include/linux/iommu.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 36f43af0af53..3e179b853380 100644
> +++ b/include/linux/iommu.h
> @@ -64,6 +64,9 @@ struct iommu_domain_geometry {
>  #define __IOMMU_DOMAIN_PT    (1U << 2)  /* Domain is identity mapped   */
>  #define __IOMMU_DOMAIN_DMA_FQ        (1U << 3)  /* DMA-API uses flush queue  
>   */
>  
> +#define __IOMMU_DOMAIN_SHARED        (1U << 4)  /* Page table shared from 
> CPU  */
> +#define __IOMMU_DOMAIN_HOST_VA       (1U << 5)  /* Host CPU virtual address 
> */
> +
>  /*
>   * This are the possible domain-types
>   *
> @@ -86,6 +89,8 @@ struct iommu_domain_geometry {
>  #define IOMMU_DOMAIN_DMA_FQ  (__IOMMU_DOMAIN_PAGING |        \
>                                __IOMMU_DOMAIN_DMA_API |       \
>                                __IOMMU_DOMAIN_DMA_FQ)
> +#define IOMMU_DOMAIN_SVA     (__IOMMU_DOMAIN_SHARED |        \
> +                              __IOMMU_DOMAIN_HOST_VA)

Is there any use for this in the core code? I feel like flags should
only be created if the core code needs to test them in some way.

> @@ -95,6 +100,7 @@ struct iommu_domain {
>       void *handler_token;
>       struct iommu_domain_geometry geometry;
>       struct iommu_dma_cookie *iova_cookie;
> +     struct mm_struct *sva_cookie;

Don't call a mm_struct a cookie please

And why do we need this in core code?

Jason
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