On 6/10/23 3:56 AM, Jason Gunthorpe wrote:
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.
I like this idea. :-)
Tested-by: Steven Price <steven.price@xxxxxxx>
Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
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 0346c05e108438..2cf523ff9c6f55 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1985,6 +1985,7 @@ 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;
@@ -1992,8 +1993,13 @@ 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) {
+ domain = ops->domain_alloc_paging(dev);
This might be problematic because not all IOMMU drivers implement this
callback now. In the missing cases, the code will always result in a
null pointer reference issue?
+ } else if (ops->domain_alloc)
+ domain = ops->domain_alloc(alloc_type);
+ else
+ return NULL;
- domain = ops->domain_alloc(alloc_type);
if (!domain)
return NULL;
@@ -2024,14 +2030,15 @@ __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);
Suppose that iommu_domain_alloc() is always called from device drivers
where device pointer is always available. Is it possible to convert it
to a real device pointer?
}
EXPORT_SYMBOL_GPL(iommu_domain_alloc);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 49331573f1d1f5..8e4d178c49c417 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);
Best regards,
baolu
