Re: [PATCH v7 4/9] ACPI/IORT: Add a helper to retrieve RMR memory regions

[Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>]

On Thu, Aug 05, 2021 at 09:07:19AM +0100, Shameer Kolothum wrote:
> Add a helper function (iort_iommu_get_rmrs()) that retrieves RMR
> memory descriptors associated with a given IOMMU. This will be used
> by IOMMU drivers to setup necessary mappings.
> 
> Invoke it from the generic helper iommu_dma_get_rmrs().
> 
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> ---
>  drivers/acpi/arm64/iort.c | 38 ++++++++++++++++++++++++++++++++++++++
>  drivers/iommu/dma-iommu.c |  4 ++++
>  include/linux/acpi_iort.h |  7 +++++++
>  3 files changed, 49 insertions(+)

Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>

> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index d76ba46ebe67..3c32d62e63b6 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -809,6 +809,42 @@ static struct acpi_iort_node *iort_get_msi_resv_iommu(struct device *dev)
>  	return NULL;
>  }
>  
> +/**
> + * iort_iommu_get_rmrs() - Helper to retrieve RMR info associated with IOMMU
> + * @iommu_fwnode: fwnode for the IOMMU
> + * @head: RMR list head to be populated
> + *
> + * Returns: 0 on success, <0 failure. Please note, we will keep the already
> + *          allocated RMR reserve regions in case of a kmemdup()
> + *          failure.
> + */
> +int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> +			struct list_head *head)
> +{
> +	struct iommu_resv_region *e;
> +	struct acpi_iort_node *iommu;
> +	int rmrs = 0;
> +
> +	iommu = iort_get_iort_node(iommu_fwnode);
> +	if (!iommu || list_empty(&iort_rmr_list))
> +		return -ENODEV;
> +
> +	list_for_each_entry(e, &iort_rmr_list, list) {
> +		struct iommu_resv_region *region;
> +
> +		if (e->fw_data.rmr.smmu != iommu)
> +			continue;
> +
> +		region = kmemdup(e, sizeof(*region), GFP_KERNEL);
> +		if (region) {
> +			list_add_tail(&region->list, head);
> +			rmrs++;
> +		}
> +	}
> +
> +	return (rmrs == 0) ? -ENODEV : 0;
> +}
> +
>  /**
>   * iort_iommu_msi_get_resv_regions - Reserved region driver helper
>   * @dev: Device from iommu_get_resv_regions()
> @@ -1041,6 +1077,8 @@ int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
>  { return 0; }
>  int iort_iommu_configure_id(struct device *dev, const u32 *input_id)
>  { return -ENODEV; }
> +int iort_iommu_get_rmrs(struct fwnode_handle *fwnode, struct list_head *head)
> +{ return -ENODEV; }
>  #endif
>  
>  static int nc_dma_get_range(struct device *dev, u64 *size)
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 2fa2445e9070..1b6e27475279 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -185,6 +185,9 @@ EXPORT_SYMBOL(iommu_put_dma_cookie);
>  int iommu_dma_get_rmrs(struct fwnode_handle *iommu_fwnode,
>  		       struct list_head *list)
>  {
> +	if (!is_of_node(iommu_fwnode))
> +		return iort_iommu_get_rmrs(iommu_fwnode, list);
> +
>  	return -EINVAL;
>  }
>  EXPORT_SYMBOL(iommu_dma_get_rmrs);
> @@ -200,6 +203,7 @@ EXPORT_SYMBOL(iommu_dma_get_rmrs);
>  void iommu_dma_put_rmrs(struct fwnode_handle *iommu_fwnode,
>  			struct list_head *list)
>  {
> +	generic_iommu_put_resv_regions(iommu_fwnode->dev, list);
>  }
>  EXPORT_SYMBOL(iommu_dma_put_rmrs);
>  
> diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
> index f1f0842a2cb2..d8c030c103f5 100644
> --- a/include/linux/acpi_iort.h
> +++ b/include/linux/acpi_iort.h
> @@ -38,6 +38,8 @@ int iort_dma_get_ranges(struct device *dev, u64 *size);
>  int iort_iommu_configure_id(struct device *dev, const u32 *id_in);
>  int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head);
>  phys_addr_t acpi_iort_dma_get_max_cpu_address(void);
> +int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> +			struct list_head *list);
>  #else
>  static inline void acpi_iort_init(void) { }
>  static inline u32 iort_msi_map_id(struct device *dev, u32 id)
> @@ -57,6 +59,11 @@ int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head)
>  
>  static inline phys_addr_t acpi_iort_dma_get_max_cpu_address(void)
>  { return PHYS_ADDR_MAX; }
> +
> +static inline
> +int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> +			struct list_head *list)
> +{ return -ENODEV; }
>  #endif
>  
>  #endif /* __ACPI_IORT_H__ */
> -- 
> 2.17.1
>