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iommufd: Register iommufd mock devices with fwspec

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Since the bus ops were retired the iommu subsystem changed to using fwspec
to match the iommu driver to the iommu device. If a device has a NULL
fwspec then it is matched to the first iommu driver with a NULL fwspec,
effectively disabling support for systems with more than one non-fwspec
iommu driver.

Thus, if the iommufd selfest are run in an x86 system that registers a
non-fwspec iommu driver they fail to bind their mock devices to the mock
iommu driver.

Fix this by allocating a software fwnode for mock iommu driver's
iommu_device, and set it to the device which mock iommu driver created.

This is done by adding a new helper iommu_mock_device_add() which abuses
the internals of the fwspec system to establish a fwspec before the device
is added and is careful not to leak it. A matching dummy fwspec is
automatically added to the mock iommu driver.

Test by "make -C toosl/testing/selftests TARGETS=iommu run_tests":
PASSED: 229 / 229 tests passed.

In addition, this issue is also can be found on amd platform, and
also tested on a amd machine.

Link: https://patch.msgid.link/r/20250925054730.3877-1-kanie@linux.alibaba.com
Fixes: 17de3f5fdd ("iommu: Retire bus ops")
Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Qinyun Tan <qinyuntan@linux.alibaba.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Guixin Liu
2025-09-25 13:47:30 +08:00
committed by Jason Gunthorpe
parent 1d235d8494
commit 2a918911ed
3 changed files with 29 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/iommu/iommu-priv.h
View File

@@ -37,6 +37,8 @@ void iommu_device_unregister_bus(struct iommu_device *iommu,
const struct bus_type *bus,
struct notifier_block *nb);
int iommu_mock_device_add(struct device *dev, struct iommu_device *iommu);
struct iommu_attach_handle *iommu_attach_handle_get(struct iommu_group *group,
ioasid_t pasid,
unsigned int type);

26
drivers/iommu/iommu.c
View File

@@ -304,6 +304,7 @@ void iommu_device_unregister_bus(struct iommu_device *iommu,
struct notifier_block *nb)
{
bus_unregister_notifier(bus, nb);
fwnode_remove_software_node(iommu->fwnode);
iommu_device_unregister(iommu);
}
EXPORT_SYMBOL_GPL(iommu_device_unregister_bus);
@@ -326,6 +327,12 @@ int iommu_device_register_bus(struct iommu_device *iommu,
if (err)
return err;
iommu->fwnode = fwnode_create_software_node(NULL, NULL);
if (IS_ERR(iommu->fwnode)) {
bus_unregister_notifier(bus, nb);
return PTR_ERR(iommu->fwnode);
}
spin_lock(&iommu_device_lock);
list_add_tail(&iommu->list, &iommu_device_list);
spin_unlock(&iommu_device_lock);
@@ -335,9 +342,28 @@ int iommu_device_register_bus(struct iommu_device *iommu,
iommu_device_unregister_bus(iommu, bus, nb);
return err;
}
WRITE_ONCE(iommu->ready, true);
return 0;
}
EXPORT_SYMBOL_GPL(iommu_device_register_bus);
int iommu_mock_device_add(struct device *dev, struct iommu_device *iommu)
{
int rc;
mutex_lock(&iommu_probe_device_lock);
rc = iommu_fwspec_init(dev, iommu->fwnode);
mutex_unlock(&iommu_probe_device_lock);
if (rc)
return rc;
rc = device_add(dev);
if (rc)
iommu_fwspec_free(dev);
return rc;
}
EXPORT_SYMBOL_GPL(iommu_mock_device_add);
#endif
static struct dev_iommu *dev_iommu_get(struct device *dev)

2
drivers/iommu/iommufd/selftest.c
View File

@@ -1126,7 +1126,7 @@ static struct mock_dev *mock_dev_create(unsigned long dev_flags)
goto err_put;
}
rc = device_add(&mdev->dev);
rc = iommu_mock_device_add(&mdev->dev, &mock_iommu.iommu_dev);
if (rc)
goto err_put;
return mdev;