Re: [PATCH 03/20] iommu/s390: Replace set_platform_dma_ops() with IOMMU_DOMAIN_PLATFORM

[Niklas Schnelle <schnelle@linux.ibm.com>]

On Mon, 2023-05-01 at 15:02 -0300, Jason Gunthorpe wrote:
> This is temporary until the S390 dma-iommu.c conversion is merged.

For anyone wanting to accelerate the conversion. Comments, testing and
reviews for the current version of my dma-iommu.c conversion patches is
welcome and the single flush queue thing might even give others
(virtio-iommu?) performance benefits:
https://lore.kernel.org/linux-iommu/20230310-dma_iommu-v8-0-2347dfbed7af@linux.ibm.com/

> 
> s390 is actually moving the dma_ops over to platform control.
> 
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>  drivers/iommu/s390-iommu.c | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c
> index fbf59a8db29b11..f0c867c57a5b9b 100644
> --- a/drivers/iommu/s390-iommu.c
> +++ b/drivers/iommu/s390-iommu.c
> @@ -142,14 +142,31 @@ static int s390_iommu_attach_device(struct iommu_domain *domain,
>  	return 0;
>  }
>  
> -static void s390_iommu_set_platform_dma(struct device *dev)
> +/*
> + * Switch control over the IOMMU to S390's internal dma_api ops
> + */
> +static int s390_iommu_platform_attach(struct iommu_domain *platform_domain,
> +				      struct device *dev)
>  {
>  	struct zpci_dev *zdev = to_zpci_dev(dev);
>  
> +	if (!zdev->s390_domain)
> +		return 0;
> +
>  	__s390_iommu_detach_device(zdev);
>  	zpci_dma_init_device(zdev);
> +	return 0;
>  }
>  
> +static struct iommu_domain_ops s390_iommu_platform_ops = {
> +	.attach_dev = s390_iommu_platform_attach,
> +};
> +
> +static struct iommu_domain s390_iommu_platform_domain = {
> +	.type = IOMMU_DOMAIN_PLATFORM,
> +	.ops = &s390_iommu_platform_ops,
> +};
> +
>  static void s390_iommu_get_resv_regions(struct device *dev,
>  					struct list_head *list)
>  {
> @@ -428,12 +445,12 @@ void zpci_destroy_iommu(struct zpci_dev *zdev)
>  }
>  
>  static const struct iommu_ops s390_iommu_ops = {
> +	.default_domain = &s390_iommu_platform_domain,
>  	.capable = s390_iommu_capable,
>  	.domain_alloc = s390_domain_alloc,
>  	.probe_device = s390_iommu_probe_device,
>  	.release_device = s390_iommu_release_device,
>  	.device_group = generic_device_group,
> -	.set_platform_dma_ops = s390_iommu_set_platform_dma,
>  	.pgsize_bitmap = SZ_4K,
>  	.get_resv_regions = s390_iommu_get_resv_regions,
>  	.default_domain_ops = &(const struct iommu_domain_ops) {

Looks good to me and I think semantically this is a good use of an
IOMMU domain type.

Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>