[RFC PATCH v3 11/12] iommu/arm-smmu: Implement the unmap_pages() IOMMU driver callback

[Will Deacon]

On Mon, Apr 05, 2021 at 12:11:11PM -0700, Isaac J. Manjarres wrote:
> Implement the unmap_pages() callback for the ARM SMMU driver
> to allow calls from iommu_unmap to unmap multiple pages of
> the same size in one call.
> 
> Signed-off-by: Isaac J. Manjarres <isaacm at codeaurora.org>
> Suggested-by: Will Deacon <will at kernel.org>
> ---
>  drivers/iommu/arm/arm-smmu/arm-smmu.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index d8c6bfde6a61..f29f1fb109f8 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -1225,6 +1225,24 @@ static size_t arm_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
>  	return ret;
>  }
>  
> +static size_t arm_smmu_unmap_pages(struct iommu_domain *domain, unsigned long iova,
> +				   size_t pgsize, size_t pgcount,
> +				   struct iommu_iotlb_gather *iotlb_gather)
> +{
> +	struct io_pgtable_ops *ops = to_smmu_domain(domain)->pgtbl_ops;
> +	struct arm_smmu_device *smmu = to_smmu_domain(domain)->smmu;
> +	size_t ret;
> +
> +	if (!ops)
> +		return 0;
> +
> +	arm_smmu_rpm_get(smmu);
> +	ret = ops->unmap_pages(ops, iova, pgsize, pgcount, iotlb_gather);
> +	arm_smmu_rpm_put(smmu);
> +
> +	return ret;
> +}

Doesn't this go wrong if we're using the short-descriptor page-table
format? (same for the next patch)

Will