Re: [PATCH v10 1/4] iommu/io-pgtable-arm: Make pgtable walker more generic

[Mostafa Saleh <smostafa@google.com>]

Hi Rob,

On Mon, Oct 28, 2024 at 02:31:37PM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> We can re-use this basic pgtable walk logic in a few places.
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Mostafa Saleh <smostafa@google.com>

> ---
>  drivers/iommu/io-pgtable-arm.c | 67 ++++++++++++++++++++++------------
>  1 file changed, 43 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 0e67f1721a3d..7e9c0f8ae138 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -749,33 +749,33 @@ static phys_addr_t arm_lpae_iova_to_phys(struct io_pgtable_ops *ops,
>  }
>  
>  struct io_pgtable_walk_data {
> -	struct iommu_dirty_bitmap	*dirty;
> +	struct io_pgtable		*iop;
> +	void				*data;
> +	int (*visit)(struct io_pgtable_walk_data *walk_data, int lvl,
> +		     arm_lpae_iopte *ptep, size_t size);
>  	unsigned long			flags;
>  	u64				addr;
>  	const u64			end;
>  };
>  
> -static int __arm_lpae_iopte_walk_dirty(struct arm_lpae_io_pgtable *data,
> -				       struct io_pgtable_walk_data *walk_data,
> -				       arm_lpae_iopte *ptep,
> -				       int lvl);
> +static int __arm_lpae_iopte_walk(struct arm_lpae_io_pgtable *data,
> +				 struct io_pgtable_walk_data *walk_data,
> +				 arm_lpae_iopte *ptep,
> +				 int lvl);
>  
> -static int io_pgtable_visit_dirty(struct arm_lpae_io_pgtable *data,
> -				  struct io_pgtable_walk_data *walk_data,
> -				  arm_lpae_iopte *ptep, int lvl)
> +static int io_pgtable_visit(struct arm_lpae_io_pgtable *data,
> +			    struct io_pgtable_walk_data *walk_data,
> +			    arm_lpae_iopte *ptep, int lvl)
>  {
>  	struct io_pgtable *iop = &data->iop;
>  	arm_lpae_iopte pte = READ_ONCE(*ptep);
>  
> -	if (iopte_leaf(pte, lvl, iop->fmt)) {
> -		size_t size = ARM_LPAE_BLOCK_SIZE(lvl, data);
> +	size_t size = ARM_LPAE_BLOCK_SIZE(lvl, data);
> +	int ret = walk_data->visit(walk_data, lvl, ptep, size);
> +	if (ret)
> +		return ret;
>  
> -		if (iopte_writeable_dirty(pte)) {
> -			iommu_dirty_bitmap_record(walk_data->dirty,
> -						  walk_data->addr, size);
> -			if (!(walk_data->flags & IOMMU_DIRTY_NO_CLEAR))
> -				iopte_set_writeable_clean(ptep);
> -		}
> +	if (iopte_leaf(pte, lvl, iop->fmt)) {
>  		walk_data->addr += size;
>  		return 0;
>  	}
> @@ -784,13 +784,13 @@ static int io_pgtable_visit_dirty(struct arm_lpae_io_pgtable *data,
>  		return -EINVAL;
>  
>  	ptep = iopte_deref(pte, data);
> -	return __arm_lpae_iopte_walk_dirty(data, walk_data, ptep, lvl + 1);
> +	return __arm_lpae_iopte_walk(data, walk_data, ptep, lvl + 1);
>  }
>  
> -static int __arm_lpae_iopte_walk_dirty(struct arm_lpae_io_pgtable *data,
> -				       struct io_pgtable_walk_data *walk_data,
> -				       arm_lpae_iopte *ptep,
> -				       int lvl)
> +static int __arm_lpae_iopte_walk(struct arm_lpae_io_pgtable *data,
> +				 struct io_pgtable_walk_data *walk_data,
> +				 arm_lpae_iopte *ptep,
> +				 int lvl)
>  {
>  	u32 idx;
>  	int max_entries, ret;
> @@ -805,7 +805,7 @@ static int __arm_lpae_iopte_walk_dirty(struct arm_lpae_io_pgtable *data,
>  
>  	for (idx = ARM_LPAE_LVL_IDX(walk_data->addr, lvl, data);
>  	     (idx < max_entries) && (walk_data->addr < walk_data->end); ++idx) {
> -		ret = io_pgtable_visit_dirty(data, walk_data, ptep + idx, lvl);
> +		ret = io_pgtable_visit(data, walk_data, ptep + idx, lvl);
>  		if (ret)
>  			return ret;
>  	}
> @@ -813,6 +813,23 @@ static int __arm_lpae_iopte_walk_dirty(struct arm_lpae_io_pgtable *data,
>  	return 0;
>  }
>  
> +static int visit_dirty(struct io_pgtable_walk_data *walk_data, int lvl,
> +		       arm_lpae_iopte *ptep, size_t size)
> +{
> +	struct iommu_dirty_bitmap *dirty = walk_data->data;
> +
> +	if (!iopte_leaf(*ptep, lvl, walk_data->iop->fmt))
> +		return 0;
> +
> +	if (iopte_writeable_dirty(*ptep)) {
> +		iommu_dirty_bitmap_record(dirty, walk_data->addr, size);
> +		if (!(walk_data->flags & IOMMU_DIRTY_NO_CLEAR))
> +			iopte_set_writeable_clean(ptep);
> +	}
> +
> +	return 0;
> +}
> +
>  static int arm_lpae_read_and_clear_dirty(struct io_pgtable_ops *ops,
>  					 unsigned long iova, size_t size,
>  					 unsigned long flags,
> @@ -821,7 +838,9 @@ static int arm_lpae_read_and_clear_dirty(struct io_pgtable_ops *ops,
>  	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
>  	struct io_pgtable_cfg *cfg = &data->iop.cfg;
>  	struct io_pgtable_walk_data walk_data = {
> -		.dirty = dirty,
> +		.iop = &data->iop,
> +		.data = dirty,
> +		.visit = visit_dirty,
>  		.flags = flags,
>  		.addr = iova,
>  		.end = iova + size,
> @@ -836,7 +855,7 @@ static int arm_lpae_read_and_clear_dirty(struct io_pgtable_ops *ops,
>  	if (data->iop.fmt != ARM_64_LPAE_S1)
>  		return -EINVAL;
>  
> -	return __arm_lpae_iopte_walk_dirty(data, &walk_data, ptep, lvl);
> +	return __arm_lpae_iopte_walk(data, &walk_data, ptep, lvl);
>  }
>  
>  static void arm_lpae_restrict_pgsizes(struct io_pgtable_cfg *cfg)
> -- 
> 2.47.0
>