[PATCH v6 23/25] iommu: Add ops->domain_alloc_paging()

Jason Gunthorpe
2023-08-03T00:09:30Z

This callback requests the driver to create only a __IOMMU_DOMAIN_PAGING
domain, so it saves a few lines in a lot of drivers needlessly checking
the type.

More critically, this allows us to sweep out all the
IOMMU_DOMAIN_UNMANAGED and IOMMU_DOMAIN_DMA checks from a lot of the
drivers, simplifying what is going on in the code and ultimately removing
the now-unused special cases in drivers where they did not support
IOMMU_DOMAIN_DMA.

domain_alloc_paging() should return a struct iommu_domain that is
functionally compatible with ARM_DMA_USE_IOMMU, dma-iommu.c and iommufd.

Be forwards looking and pass in a 'struct device *' argument. We can
provide this when allocating the default_domain. No drivers will look at
this.

Tested-by: Steven Price <steven.price@arm.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
drivers/iommu/iommu.c | 13 ++++++++++---
include/linux/iommu.h | 3 +++
2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index bc8b35e31b5343..5b5cf74edc7e53 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1999,6 +1999,7 @@ void iommu_set_fault_handler(struct iommu_domain *domain,
EXPORT_SYMBOL_GPL(iommu_set_fault_handler);

static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops,
+ struct device *dev,
unsigned int type)
{
struct iommu_domain *domain;
@@ -2006,8 +2007,13 @@ static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops,

if (alloc_type == IOMMU_DOMAIN_IDENTITY && ops->identity_domain)
return ops->identity_domain;
+ else if (type & __IOMMU_DOMAIN_PAGING && ops->domain_alloc_paging) {
+ domain = ops->domain_alloc_paging(dev);
+ } else if (ops->domain_alloc)
+ domain = ops->domain_alloc(alloc_type);
+ else
+ return NULL;

- domain = ops->domain_alloc(alloc_type);
if (!domain)
return NULL;

@@ -2038,14 +2044,15 @@ __iommu_group_domain_alloc(struct iommu_group *group, unsigned int type)

lockdep_assert_held(&group->mutex);

- return __iommu_domain_alloc(dev_iommu_ops(dev), type);
+ return __iommu_domain_alloc(dev_iommu_ops(dev), dev, type);
}

struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
{
if (bus == NULL || bus->iommu_ops == NULL)
return NULL;
- return __iommu_domain_alloc(bus->iommu_ops, IOMMU_DOMAIN_UNMANAGED);
+ return __iommu_domain_alloc(bus->iommu_ops, NULL,
+ IOMMU_DOMAIN_UNMANAGED);
}
EXPORT_SYMBOL_GPL(iommu_domain_alloc);

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index df54066c262db4..8f69866c868e04 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -233,6 +233,8 @@ struct iommu_iotlb_gather {
* struct iommu_ops - iommu ops and capabilities
* @capable: check capability
* @domain_alloc: allocate iommu domain
+ * @domain_alloc_paging: Allocate an iommu_domain that can be used for
+ * UNMANAGED, DMA, and DMA_FQ domain types.
* @probe_device: Add device to iommu driver handling
* @release_device: Remove device from iommu driver handling
* @probe_finalize: Do final setup work after the device is added to an IOMMU
@@ -264,6 +266,7 @@ struct iommu_ops {

/* Domain allocation and freeing by the iommu driver */
struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type);
+ struct iommu_domain *(*domain_alloc_paging)(struct device *dev);

struct iommu_device *(*probe_device)(struct device *dev);
void (*release_device)(struct device *dev);
--
2.41.0