RE: [PATCH v3 02/10] iommu/vt-d: Extend dmar_domain to support nested domain

[Tian, Kevin]

> From: Liu, Yi L <yi.l.liu@xxxxxxxxx>
> Sent: Thursday, May 11, 2023 10:51 PM
> 
> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> 
> The nested domain fields are exclusive to those that used for a DMA
> remapping domain. Use union to avoid memory waste.
> 
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> ---
>  drivers/iommu/intel/iommu.h | 35 +++++++++++++++++++++++++++++------
>  1 file changed, 29 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
> index 1c5e1d88862b..e818520f4068 100644
> --- a/drivers/iommu/intel/iommu.h
> +++ b/drivers/iommu/intel/iommu.h
> @@ -596,15 +596,38 @@ struct dmar_domain {
>  	spinlock_t lock;		/* Protect device tracking lists */
>  	struct list_head devices;	/* all devices' list */
> 
> -	struct dma_pte	*pgd;		/* virtual address */
> -	int		gaw;		/* max guest address width */
> -
> -	/* adjusted guest address width, 0 is level 2 30-bit */
> -	int		agaw;
>  	int		iommu_superpage;/* Level of superpages supported:
>  					   0 == 4KiB (no superpages), 1 ==
> 2MiB,
>  					   2 == 1GiB, 3 == 512GiB, 4 == 1TiB */
> -	u64		max_addr;	/* maximum mapped address */
> +	union {
> +		/* DMA remapping domain */
> +		struct {
> +			/* virtual address */
> +			struct dma_pte	*pgd;
> +			/* max guest address width */
> +			int		gaw;
> +			/*
> +			 * adjusted guest address width:
> +			 *   0: level 2 30-bit
> +			 *   1: level 3 39-bit
> +			 *   2: level 4 48-bit
> +			 *   3: level 5 57-bit
> +			 */
> +			int		agaw;
> +			/* maximum mapped address */
> +			u64		max_addr;
> +		};

what about 'nid'?

> +
> +		/* Nested user domain */
> +		struct {
> +			/* 2-level page table the user domain nested */

/* parent page table which the user domain is nested on */

> +			struct dmar_domain *s2_domain;
> +			/* user page table pointer (in GPA) */
> +			unsigned long s1_pgtbl;
> +			/* page table attributes */
> +			struct iommu_hwpt_intel_vtd s1_cfg;
> +		};
> +	};
> 
>  	struct iommu_domain domain;	/* generic domain data structure for
>  					   iommu core */
> --
> 2.34.1