Re: [PATCH v7 08/15] iommu: Add support for the map_pages() callback

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

On 6/16/21 9:38 PM, Georgi Djakov wrote:
> From: "Isaac J. Manjarres" <isaacm@codeaurora.org>
> 
> Since iommu_pgsize can calculate how many pages of the
> same size can be mapped/unmapped before the next largest
> page size boundary, add support for invoking an IOMMU
> driver's map_pages() callback, if it provides one.
> 
> Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
> Suggested-by: Will Deacon <will@kernel.org>
> Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com>
> ---
>   drivers/iommu/iommu.c | 43 +++++++++++++++++++++++++++++++++++--------
>   1 file changed, 35 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 725622c7e603..70a729ce88b1 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2429,6 +2429,30 @@ static size_t iommu_pgsize(struct iommu_domain *domain, unsigned long iova,
>   	return pgsize;
>   }
>   
> +static int __iommu_map_pages(struct iommu_domain *domain, unsigned long iova,
> +			     phys_addr_t paddr, size_t size, int prot,
> +			     gfp_t gfp, size_t *mapped)
> +{
> +	const struct iommu_ops *ops = domain->ops;
> +	size_t pgsize, count;
> +	int ret;
> +
> +	pgsize = iommu_pgsize(domain, iova, paddr, size, &count);
> +
> +	pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx count %zu\n",
> +		 iova, &paddr, pgsize, count);
> +
> +	if (ops->map_pages) {
> +		ret = ops->map_pages(domain, iova, paddr, pgsize, count, prot,
> +				     gfp, mapped);
> +	} else {
> +		ret = ops->map(domain, iova, paddr, pgsize, prot, gfp);
> +		*mapped = ret ? 0 : pgsize;
> +	}
> +
> +	return ret;
> +}
> +
>   static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
>   		       phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
>   {
> @@ -2439,7 +2463,7 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
>   	phys_addr_t orig_paddr = paddr;
>   	int ret = 0;
>   
> -	if (unlikely(ops->map == NULL ||
> +	if (unlikely(!(ops->map || ops->map_pages) ||
>   		     domain->pgsize_bitmap == 0UL))
>   		return -ENODEV;
>   
> @@ -2463,18 +2487,21 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
>   	pr_debug("map: iova 0x%lx pa %pa size 0x%zx\n", iova, &paddr, size);
>   
>   	while (size) {
> -		size_t pgsize = iommu_pgsize(domain, iova, paddr, size, NULL);
> +		size_t mapped = 0;
>   
> -		pr_debug("mapping: iova 0x%lx pa %pa pgsize 0x%zx\n",
> -			 iova, &paddr, pgsize);
> -		ret = ops->map(domain, iova, paddr, pgsize, prot, gfp);
> +		ret = __iommu_map_pages(domain, iova, paddr, size, prot, gfp,
> +					&mapped);
> +		/*
> +		 * Some pages may have been mapped, even if an error occurred,
> +		 * so we should account for those so they can be unmapped.
> +		 */
> +		size -= mapped;
>   
>   		if (ret)
>   			break;
>   
> -		iova += pgsize;
> -		paddr += pgsize;
> -		size -= pgsize;
> +		iova += mapped;
> +		paddr += mapped;
>   	}
>   
>   	/* unroll mapping in case something went wrong */
> 

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu