On Wed, Aug 23, 2023 at 01:47:16PM -0300, Jason Gunthorpe wrote:
> This is used when the iommu driver is taking control of the dma_ops,
> currently only on S390 and power spapr. It is designed to preserve the
> original ops->detach_dev() semantic that these S390 was built around.
>
> Provide an opaque domain type and a 'default_domain' ops value that allows
> the driver to trivially force any single domain as the default domain.
>
> Update iommufd selftest to use this instead of set_platform_dma_ops
>
> Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> ---
> drivers/iommu/iommu.c | 13 +++++++++++++
> drivers/iommu/iommufd/selftest.c | 14 +++++---------
> include/linux/iommu.h | 6 ++++++
> 3 files changed, 24 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 33bd1107090720..7cedb0640290c8 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -184,6 +184,8 @@ static const char *iommu_domain_type_str(unsigned int t)
> case IOMMU_DOMAIN_DMA:
> case IOMMU_DOMAIN_DMA_FQ:
> return "Translated";
> + case IOMMU_DOMAIN_PLATFORM:
> + return "Platform";
> default:
> return "Unknown";
> }
> @@ -1752,6 +1754,17 @@ iommu_group_alloc_default_domain(struct iommu_group *group, int req_type)
>
> lockdep_assert_held(&group->mutex);
>
> + /*
> + * Allow legacy drivers to specify the domain that will be the default
> + * domain. This should always be either an IDENTITY or PLATFORM domain.
> + * Do not use in new drivers.
> + */
Would it be worthwhile to mention this in iommu.h for the iommu_ops default_domain?
> + if (bus->iommu_ops->default_domain) {
> + if (req_type)
> + return ERR_PTR(-EINVAL);
> + return bus->iommu_ops->default_domain;
> + }
> +
> if (req_type)
> return __iommu_group_alloc_default_domain(bus, group, req_type);
>
> diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c
> index d48a202a7c3b81..fb981ba97c4e87 100644
> --- a/drivers/iommu/iommufd/selftest.c
> +++ b/drivers/iommu/iommufd/selftest.c
> @@ -281,14 +281,6 @@ static bool mock_domain_capable(struct device *dev, enum iommu_cap cap)
> return cap == IOMMU_CAP_CACHE_COHERENCY;
> }
>
> -static void mock_domain_set_plaform_dma_ops(struct device *dev)
> -{
> - /*
> - * mock doesn't setup default domains because we can't hook into the
> - * normal probe path
> - */
> -}
> -
> static struct iommu_device mock_iommu_device = {
> };
>
> @@ -298,12 +290,16 @@ static struct iommu_device *mock_probe_device(struct device *dev)
> }
>
> static const struct iommu_ops mock_ops = {
> + /*
> + * IOMMU_DOMAIN_BLOCKED cannot be returned from def_domain_type()
> + * because it is zero.
> + */
> + .default_domain = &mock_blocking_domain,
> .owner = THIS_MODULE,
> .pgsize_bitmap = MOCK_IO_PAGE_SIZE,
> .hw_info = mock_domain_hw_info,
> .domain_alloc = mock_domain_alloc,
> .capable = mock_domain_capable,
> - .set_platform_dma_ops = mock_domain_set_plaform_dma_ops,
> .device_group = generic_device_group,
> .probe_device = mock_probe_device,
> .default_domain_ops =
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index d0920b2a9f1c0e..48a18b6e07abff 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -64,6 +64,7 @@ struct iommu_domain_geometry {
> #define __IOMMU_DOMAIN_DMA_FQ (1U << 3) /* DMA-API uses flush queue */
>
> #define __IOMMU_DOMAIN_SVA (1U << 4) /* Shared process address space */
> +#define __IOMMU_DOMAIN_PLATFORM (1U << 5)
>
> #define IOMMU_DOMAIN_ALLOC_FLAGS ~__IOMMU_DOMAIN_DMA_FQ
> /*
> @@ -81,6 +82,8 @@ struct iommu_domain_geometry {
> * invalidation.
> * IOMMU_DOMAIN_SVA - DMA addresses are shared process addresses
> * represented by mm_struct's.
> + * IOMMU_DOMAIN_PLATFORM - Legacy domain for drivers that do their own
> + * dma_api stuff. Do not use in new drivers.
> */
> #define IOMMU_DOMAIN_BLOCKED (0U)
> #define IOMMU_DOMAIN_IDENTITY (__IOMMU_DOMAIN_PT)
> @@ -91,6 +94,7 @@ struct iommu_domain_geometry {
> __IOMMU_DOMAIN_DMA_API | \
> __IOMMU_DOMAIN_DMA_FQ)
> #define IOMMU_DOMAIN_SVA (__IOMMU_DOMAIN_SVA)
> +#define IOMMU_DOMAIN_PLATFORM (__IOMMU_DOMAIN_PLATFORM)
>
> struct iommu_domain {
> unsigned type;
> @@ -262,6 +266,7 @@ struct iommu_iotlb_gather {
> * @owner: Driver module providing these ops
> * @identity_domain: An always available, always attachable identity
> * translation.
> + * @default_domain: If not NULL this will always be set as the default domain.
> */
> struct iommu_ops {
> bool (*capable)(struct device *dev, enum iommu_cap);
> @@ -297,6 +302,7 @@ struct iommu_ops {
> unsigned long pgsize_bitmap;
> struct module *owner;
> struct iommu_domain *identity_domain;
> + struct iommu_domain *default_domain;
> };
>
> /**
> --
> 2.41.0
>
