Re: [PATCH v2 04/14] iommu/io-pgtable-arm-v7s: Add paddr_to_iopte and iopte_to_paddr helpers

[Robin Murphy <Robin.Murphy@arm.com>]

[ apologies if anyone gets this twice, looks like our email's eaten 
itself again... ]

On 24/09/2018 09:58, Yong Wu wrote:
> Add two helper functions: paddr_to_iopte and iopte_to_paddr.

Nice and tidy! (although it will need rebasing now, but I think that's 
just context conflicts)

> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
>   drivers/iommu/io-pgtable-arm-v7s.c | 45 ++++++++++++++++++++++++++++----------
>   1 file changed, 33 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
> index b5948ba..fa3b9ec 100644
> --- a/drivers/iommu/io-pgtable-arm-v7s.c
> +++ b/drivers/iommu/io-pgtable-arm-v7s.c
> @@ -173,18 +173,38 @@ struct arm_v7s_io_pgtable {
>   	spinlock_t		split_lock;
>   };
>   
> +static bool arm_v7s_pte_is_cont(arm_v7s_iopte pte, int lvl);
> +
>   static dma_addr_t __arm_v7s_dma_addr(void *pages)
>   {
>   	return (dma_addr_t)virt_to_phys(pages);
>   }
>   
> -static arm_v7s_iopte *iopte_deref(arm_v7s_iopte pte, int lvl)
> +static arm_v7s_iopte paddr_to_iopte(phys_addr_t paddr, int lvl,
> +				    struct arm_v7s_io_pgtable *data)

Nit: it seems to work out a little cleaner if we pass the io_pgtable_cfg 
to these helpers directly, rather than re-deriving it from data each time.

Otherwise, though,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

>   {
> +	return paddr & ARM_V7S_LVL_MASK(lvl);
> +}
> +
> +static phys_addr_t iopte_to_paddr(arm_v7s_iopte pte, int lvl,
> +				  struct arm_v7s_io_pgtable *data)
> +{
> +	arm_v7s_iopte mask;
> +
>   	if (ARM_V7S_PTE_IS_TABLE(pte, lvl))
> -		pte &= ARM_V7S_TABLE_MASK;
> +		mask = ARM_V7S_TABLE_MASK;
> +	else if (arm_v7s_pte_is_cont(pte, lvl))
> +		mask = ARM_V7S_LVL_MASK(lvl) * ARM_V7S_CONT_PAGES;
>   	else
> -		pte &= ARM_V7S_LVL_MASK(lvl);
> -	return phys_to_virt(pte);
> +		mask = ARM_V7S_LVL_MASK(lvl);
> +
> +	return pte & mask;
> +}
> +
> +static arm_v7s_iopte *iopte_deref(arm_v7s_iopte pte, int lvl,
> +				  struct arm_v7s_io_pgtable *data)
> +{
> +	return phys_to_virt(iopte_to_paddr(pte, lvl, data));
>   }
>   
>   static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
> @@ -396,7 +416,7 @@ static int arm_v7s_init_pte(struct arm_v7s_io_pgtable *data,
>   	if (num_entries > 1)
>   		pte = arm_v7s_pte_to_cont(pte, lvl);
>   
> -	pte |= paddr & ARM_V7S_LVL_MASK(lvl);
> +	pte |= paddr_to_iopte(paddr, lvl, data);
>   
>   	__arm_v7s_set_pte(ptep, pte, num_entries, cfg);
>   	return 0;
> @@ -462,7 +482,7 @@ static int __arm_v7s_map(struct arm_v7s_io_pgtable *data, unsigned long iova,
>   	}
>   
>   	if (ARM_V7S_PTE_IS_TABLE(pte, lvl)) {
> -		cptep = iopte_deref(pte, lvl);
> +		cptep = iopte_deref(pte, lvl, data);
>   	} else if (pte) {
>   		/* We require an unmap first */
>   		WARN_ON(!selftest_running);
> @@ -512,7 +532,8 @@ static void arm_v7s_free_pgtable(struct io_pgtable *iop)
>   		arm_v7s_iopte pte = data->pgd[i];
>   
>   		if (ARM_V7S_PTE_IS_TABLE(pte, 1))
> -			__arm_v7s_free_table(iopte_deref(pte, 1), 2, data);
> +			__arm_v7s_free_table(iopte_deref(pte, 1, data),
> +					     2, data);
>   	}
>   	__arm_v7s_free_table(data->pgd, 1, data);
>   	kmem_cache_destroy(data->l2_tables);
> @@ -582,7 +603,7 @@ static size_t arm_v7s_split_blk_unmap(struct arm_v7s_io_pgtable *data,
>   		if (!ARM_V7S_PTE_IS_TABLE(pte, 1))
>   			return 0;
>   
> -		tablep = iopte_deref(pte, 1);
> +		tablep = iopte_deref(pte, 1, data);
>   		return __arm_v7s_unmap(data, iova, size, 2, tablep);
>   	}
>   
> @@ -640,7 +661,7 @@ static size_t __arm_v7s_unmap(struct arm_v7s_io_pgtable *data,
>   				io_pgtable_tlb_add_flush(iop, iova, blk_size,
>   					ARM_V7S_BLOCK_SIZE(lvl + 1), false);
>   				io_pgtable_tlb_sync(iop);
> -				ptep = iopte_deref(pte[i], lvl);
> +				ptep = iopte_deref(pte[i], lvl, data);
>   				__arm_v7s_free_table(ptep, lvl + 1, data);
>   			} else {
>   				io_pgtable_tlb_add_flush(iop, iova, blk_size,
> @@ -658,7 +679,7 @@ static size_t __arm_v7s_unmap(struct arm_v7s_io_pgtable *data,
>   	}
>   
>   	/* Keep on walkin' */
> -	ptep = iopte_deref(pte[0], lvl);
> +	ptep = iopte_deref(pte[0], lvl, data);
>   	return __arm_v7s_unmap(data, iova, size, lvl + 1, ptep);
>   }
>   
> @@ -684,7 +705,7 @@ static phys_addr_t arm_v7s_iova_to_phys(struct io_pgtable_ops *ops,
>   	do {
>   		ptep += ARM_V7S_LVL_IDX(iova, ++lvl);
>   		pte = READ_ONCE(*ptep);
> -		ptep = iopte_deref(pte, lvl);
> +		ptep = iopte_deref(pte, lvl, data);
>   	} while (ARM_V7S_PTE_IS_TABLE(pte, lvl));
>   
>   	if (!ARM_V7S_PTE_IS_VALID(pte))
> @@ -693,7 +714,7 @@ static phys_addr_t arm_v7s_iova_to_phys(struct io_pgtable_ops *ops,
>   	mask = ARM_V7S_LVL_MASK(lvl);
>   	if (arm_v7s_pte_is_cont(pte, lvl))
>   		mask *= ARM_V7S_CONT_PAGES;
> -	return (pte & mask) | (iova & ~mask);
> +	return iopte_to_paddr(pte, lvl, data) | (iova & ~mask);
>   }
>   
>   static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
>