RE: [PATCH RFC 02/11] iommu: Add iommu_domain type for SVA

["Tian, Kevin" <kevin.tian@intel.com>]

> From: Lu Baolu <baolu.lu@linux.intel.com>
> Sent: Sunday, March 20, 2022 2:40 PM
> 
> 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 <baolu.lu@linux.intel.com>
> ---
>  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
> --- a/include/linux/iommu.h
> +++ 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 */

suppose the SHARED bit will be also used for KVM page table sharing and
HOST_VA bit is to differentiate mm sharing from the latter?

> +
>  /*
>   * 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)
> 
>  struct iommu_domain {
>  	unsigned type;
> @@ -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;
>  };
> 
>  static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
> --
> 2.25.1