Re: [PATCH v4 2/6] iommu/sva: Move PASID helpers to sva code

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

On 2023/3/2 7:56, Jacob Pan wrote:
> Preparing to remove IOASID infrastructure, PASID management will be
> under SVA code. Decouple mm code from IOASID. Use iommu-help.h instead
> of iommu.h to prevent circular inclusion.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> v4: (Jason's comments)
> 	- delete and open code mm_set_pasid
> 	- keep mm_init_pasid() as inline for fork performance
> ---
>   drivers/iommu/iommu-sva.c    | 10 +++++++++-
>   include/linux/ioasid.h       |  2 +-
>   include/linux/iommu-helper.h |  1 +
>   include/linux/sched/mm.h     | 18 ++----------------
>   4 files changed, 13 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> index 24bf9b2b58aa..376b2a9e2543 100644
> --- a/drivers/iommu/iommu-sva.c
> +++ b/drivers/iommu/iommu-sva.c
> @@ -44,7 +44,7 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
>   	if (!pasid_valid(pasid))
>   		ret = -ENOMEM;
>   	else
> -		mm_pasid_set(mm, pasid);
> +		mm->pasid = ret;

This seems obviously incorrect.

		mm->pasid = pasid;

?

>   out:
>   	mutex_unlock(&iommu_sva_lock);
>   	return ret;
> @@ -238,3 +238,11 @@ iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)
>   
>   	return status;
>   }
> +
> +void mm_pasid_drop(struct mm_struct *mm)
> +{
> +	if (pasid_valid(mm->pasid)) {
> +		ioasid_free(mm->pasid);
> +		mm->pasid = INVALID_IOASID;
> +	}
> +}
> diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
> index af1c9d62e642..2c502e77ee78 100644
> --- a/include/linux/ioasid.h
> +++ b/include/linux/ioasid.h
> @@ -4,8 +4,8 @@
>   
>   #include <linux/types.h>
>   #include <linux/errno.h>
> +#include <linux/iommu-helper.h>
>   
> -#define INVALID_IOASID ((ioasid_t)-1)
>   typedef unsigned int ioasid_t;
>   typedef ioasid_t (*ioasid_alloc_fn_t)(ioasid_t min, ioasid_t max, void *data);
>   typedef void (*ioasid_free_fn_t)(ioasid_t ioasid, void *data);
> diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
> index 74be34f3a20a..0aa922f6bfad 100644
> --- a/include/linux/iommu-helper.h
> +++ b/include/linux/iommu-helper.h
> @@ -40,5 +40,6 @@ static inline unsigned long iommu_num_pages(unsigned long addr,
>   
>   	return DIV_ROUND_UP(size, io_page_size);
>   }
> +#define INVALID_IOASID	(-1U)
>   
>   #endif
> diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
> index 2a243616f222..ae5a3f16b321 100644
> --- a/include/linux/sched/mm.h
> +++ b/include/linux/sched/mm.h
> @@ -8,7 +8,7 @@
>   #include <linux/mm_types.h>
>   #include <linux/gfp.h>
>   #include <linux/sync_core.h>
> -#include <linux/ioasid.h>
> +#include <linux/iommu-helper.h>
>   
>   /*
>    * Routines for handling mm_structs
> @@ -456,23 +456,9 @@ static inline void mm_pasid_init(struct mm_struct *mm)
>   {
>   	mm->pasid = INVALID_IOASID;
>   }
> -
> -/* Associate a PASID with an mm_struct: */
> -static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid)
> -{
> -	mm->pasid = pasid;
> -}
> -
> -static inline void mm_pasid_drop(struct mm_struct *mm)
> -{
> -	if (pasid_valid(mm->pasid)) {
> -		ioasid_free(mm->pasid);
> -		mm->pasid = INVALID_IOASID;
> -	}
> -}
> +void mm_pasid_drop(struct mm_struct *mm);
>   #else
>   static inline void mm_pasid_init(struct mm_struct *mm) {}
> -static inline void mm_pasid_set(struct mm_struct *mm, u32 pasid) {}
>   static inline void mm_pasid_drop(struct mm_struct *mm) {}

Above mm_pasid_drop() should also be removed.

>   #endif
>   

Best regards,
baolu