Re: [PATCH v7 2/7] iommu/sva: Move PASID helpers to sva code

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Mar 20, 2023 at 11:59:05AM -0700, Jacob Pan wrote:
> Preparing to remove IOASID infrastructure, PASID management will be
> under SVA code. Decouple mm code from IOASID.
> 
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
> v7:
> 	- use CONFIG_IOMMU_SVA around PASID helpers in fork.c, Fixes a
> 	compile problem.
> v6:
> 	- put helpers under iommu.h instead of iommu-helper.h
> v5:
> 	- move definition of helpers to iommu code to be consistent with
> 	  declarations. (Kevin)
> 	- fix patch partitioning bug (Baolu)
> v4:
> 	- 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    |  6 +-----
>  include/linux/iommu.h     | 14 +++++++++++++-
>  include/linux/sched/mm.h  | 26 --------------------------
>  kernel/fork.c             |  5 +++++
>  5 files changed, 28 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> index 24bf9b2b58aa..fcfdc80a3939 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 = 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..bdee937da907 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.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);
> @@ -40,10 +40,6 @@ void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid,
>  int ioasid_register_allocator(struct ioasid_allocator_ops *allocator);
>  void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator);
>  int ioasid_set_data(ioasid_t ioasid, void *data);
> -static inline bool pasid_valid(ioasid_t ioasid)
> -{
> -	return ioasid != INVALID_IOASID;
> -}
>  
>  #else /* !CONFIG_IOASID */
>  static inline ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min,
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 6595454d4f48..d3f81dc6e4dd 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -13,7 +13,6 @@
>  #include <linux/errno.h>
>  #include <linux/err.h>
>  #include <linux/of.h>
> -#include <linux/ioasid.h>
>  #include <uapi/linux/iommu.h>
>  
>  #define IOMMU_READ	(1 << 0)
> @@ -192,6 +191,8 @@ enum iommu_dev_features {
>  };
>  
>  #define IOMMU_PASID_INVALID	(-1U)
> +typedef unsigned int ioasid_t;
> +#define INVALID_IOASID ((ioasid_t)-1)
>  
>  #ifdef CONFIG_IOMMU_API
>  
> @@ -1172,7 +1173,16 @@ static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream
>  	return false;
>  }
>  
> +static inline bool pasid_valid(ioasid_t ioasid)
> +{
> +	return ioasid != INVALID_IOASID;
> +}
>  #ifdef CONFIG_IOMMU_SVA
> +static inline void mm_pasid_init(struct mm_struct *mm)
> +{
> +	mm->pasid = INVALID_IOASID;
> +}
> +void mm_pasid_drop(struct mm_struct *mm);
>  struct iommu_sva *iommu_sva_bind_device(struct device *dev,
>  					struct mm_struct *mm);
>  void iommu_sva_unbind_device(struct iommu_sva *handle);
> @@ -1192,6 +1202,8 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
>  {
>  	return IOMMU_PASID_INVALID;
>  }
> +static inline void mm_pasid_init(struct mm_struct *mm) {}
> +static inline void mm_pasid_drop(struct mm_struct *mm) {}
>  #endif /* CONFIG_IOMMU_SVA */
>  
>  #endif /* __LINUX_IOMMU_H */
> diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
> index 2a243616f222..da9712a3ba73 100644
> --- a/include/linux/sched/mm.h
> +++ b/include/linux/sched/mm.h
> @@ -8,7 +8,6 @@
>  #include <linux/mm_types.h>
>  #include <linux/gfp.h>
>  #include <linux/sync_core.h>
> -#include <linux/ioasid.h>
>  
>  /*
>   * Routines for handling mm_structs
> @@ -451,29 +450,4 @@ static inline void membarrier_update_current_mm(struct mm_struct *next_mm)
>  }
>  #endif
>  
> -#ifdef CONFIG_IOMMU_SVA
> -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;
> -	}
> -}
> -#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) {}
> -#endif


> @@ -794,7 +795,9 @@ void __mmdrop(struct mm_struct *mm)
>  	mmu_notifier_subscriptions_destroy(mm);
>  	check_mm(mm);
>  	put_user_ns(mm->user_ns);
> +#ifdef CONFIG_IOMMU_SVA	
>  	mm_pasid_drop(mm);
> +#endif
>  
>  	for (i = 0; i < NR_MM_COUNTERS; i++)
>  		percpu_counter_destroy(&mm->rss_stat[i]);
> @@ -1140,7 +1143,9 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
>  	mm_init_cpumask(mm);
>  	mm_init_aio(mm);
>  	mm_init_owner(mm, p);
> +#ifdef CONFIG_IOMMU_SVA	
>  	mm_pasid_init(mm);
> +#endif

No ifdef here, you correctly made static inline dummy functions above.

Jason