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iommu: Handle default domain attach failure 

We wouldn't normally expect ops->attach_dev() to fail, but on IOMMUs
with limited hardware resources, or generally misconfigured systems,
it is certainly possible. We report failure correctly from the external
iommu_attach_device() interface, but do not do so in iommu_group_add()
when attaching to the default domain. The result of failure there is
that the device, group and domain all get left in a broken,
part-configured state which leads to weird errors and misbehaviour down
the line when IOMMU API calls sort-of-but-don't-quite work.

Check the return value of __iommu_attach_device() on the default domain,
and refactor the error handling paths to cope with its failure and clean
up correctly in such cases.

Fixes: e39cb8a3aa ("iommu: Make sure a device is always attached to a domain")
Reported-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
hifive-unleashed-5.1
Robin Murphy 2017-01-16 12:58:07 +00:00 committed by Joerg Roedel
parent eba484b51b
commit 797a8b4d76
1 changed files with 24 additions and 13 deletions
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37
drivers/iommu/iommu.c
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@ -383,36 +383,30 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev)
device->dev = dev;
ret = sysfs_create_link(&dev->kobj, &group->kobj, "iommu_group");
if (ret) {
kfree(device);
return ret;
}
if (ret)
goto err_free_device;
device->name = kasprintf(GFP_KERNEL, "%s", kobject_name(&dev->kobj));
rename:
if (!device->name) {
sysfs_remove_link(&dev->kobj, "iommu_group");
kfree(device);
return -ENOMEM;
ret = -ENOMEM;
goto err_remove_link;
}
ret = sysfs_create_link_nowarn(group->devices_kobj,
&dev->kobj, device->name);
if (ret) {
kfree(device->name);
if (ret == -EEXIST && i >= 0) {
/*
* Account for the slim chance of collision
* and append an instance to the name.
*/
kfree(device->name);
device->name = kasprintf(GFP_KERNEL, "%s.%d",
kobject_name(&dev->kobj), i++);
goto rename;
}
sysfs_remove_link(&dev->kobj, "iommu_group");
kfree(device);
return ret;
goto err_free_name;
}
kobject_get(group->devices_kobj);
@ -424,8 +418,10 @@ rename:
mutex_lock(&group->mutex);
list_add_tail(&device->list, &group->devices);
if (group->domain)
__iommu_attach_device(group->domain, dev);
ret = __iommu_attach_device(group->domain, dev);
mutex_unlock(&group->mutex);
if (ret)
goto err_put_group;
/* Notify any listeners about change to group. */
blocking_notifier_call_chain(&group->notifier,
@ -436,6 +432,21 @@ rename:
pr_info("Adding device %s to group %d\n", dev_name(dev), group->id);
return 0;
err_put_group:
mutex_lock(&group->mutex);
list_del(&device->list);
mutex_unlock(&group->mutex);
dev->iommu_group = NULL;
kobject_put(group->devices_kobj);
err_free_name:
kfree(device->name);
err_remove_link:
sysfs_remove_link(&dev->kobj, "iommu_group");
err_free_device:
kfree(device);
pr_err("Failed to add device %s to group %d: %d\n", dev_name(dev), group->id, ret);
return ret;
}
EXPORT_SYMBOL_GPL(iommu_group_add_device);