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iommu: Add iommu_init/deinit_device() paired functions

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Move the driver init and destruction code into two logically paired
functions.

There is a subtle ordering dependency in how the group's domains are
freed, the current code does the kobject_put() on the group which will
hopefully trigger the free of the domains before the module_put() that
protects the domain->ops.

Reorganize this to be explicit and documented. The domains are cleaned up
by iommu_deinit_device() if it is the last device to be deinit'd from the
group.  This must be done in a specific order - after
ops->release_device() and before the module_put(). Make it very clear and
obvious by putting the order directly in one function.

Leave WARN_ON's in case the refcounting gets messed up somehow.

This also moves the module_put() and dev_iommu_free() under the
group->mutex to keep the code simple.

Building paired functions like this helps ensure that error cleanup flows
in __iommu_probe_device() are correct because they share the same code
that handles the normal flow. These details become relavent as following
patches add more error unwind into __iommu_probe_device(), and ultimately
a following series adds fine-grained locking to __iommu_probe_device().

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/5-v3-328044aa278c+45e49-iommu_probe_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Jason Gunthorpe 2023-06-05 21:59:43 -03:00 • committed by Joerg Roedel
parent df15d76dca
commit aa0958570f
1 changed files with 112 additions and 79 deletions
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191
drivers/iommu/iommu.c
View file

@ -332,10 +332,99 @@ static u32 dev_iommu_get_max_pasids(struct device *dev)
return min_t(u32, max_pasids, dev->iommu->iommu_dev->max_pasids);
}
/*
* Init the dev->iommu and dev->iommu_group in the struct device and get the
* driver probed
*/
static int iommu_init_device(struct device *dev, const struct iommu_ops *ops)
{
struct iommu_device *iommu_dev;
struct iommu_group *group;
int ret;
if (!dev_iommu_get(dev))
return -ENOMEM;
if (!try_module_get(ops->owner)) {
ret = -EINVAL;
goto err_free;
}
iommu_dev = ops->probe_device(dev);
if (IS_ERR(iommu_dev)) {
ret = PTR_ERR(iommu_dev);
goto err_module_put;
}
group = ops->device_group(dev);
if (WARN_ON_ONCE(group == NULL))
group = ERR_PTR(-EINVAL);
if (IS_ERR(group)) {
ret = PTR_ERR(group);
goto err_release;
}
dev->iommu_group = group;
dev->iommu->iommu_dev = iommu_dev;
dev->iommu->max_pasids = dev_iommu_get_max_pasids(dev);
if (ops->is_attach_deferred)
dev->iommu->attach_deferred = ops->is_attach_deferred(dev);
return 0;
err_release:
if (ops->release_device)
ops->release_device(dev);
err_module_put:
module_put(ops->owner);
err_free:
dev_iommu_free(dev);
return ret;
}
static void iommu_deinit_device(struct device *dev)
{
struct iommu_group *group = dev->iommu_group;
const struct iommu_ops *ops = dev_iommu_ops(dev);
lockdep_assert_held(&group->mutex);
/*
* release_device() must stop using any attached domain on the device.
* If there are still other devices in the group they are not effected
* by this callback.
*
* The IOMMU driver must set the device to either an identity or
* blocking translation and stop using any domain pointer, as it is
* going to be freed.
*/
if (ops->release_device)
ops->release_device(dev);
/*
* If this is the last driver to use the group then we must free the
* domains before we do the module_put().
*/
if (list_empty(&group->devices)) {
if (group->default_domain) {
iommu_domain_free(group->default_domain);
group->default_domain = NULL;
}
if (group->blocking_domain) {
iommu_domain_free(group->blocking_domain);
group->blocking_domain = NULL;
}
group->domain = NULL;
}
/* Caller must put iommu_group */
dev->iommu_group = NULL;
module_put(ops->owner);
dev_iommu_free(dev);
}
static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
{
const struct iommu_ops *ops = dev->bus->iommu_ops;
struct iommu_device *iommu_dev;
struct iommu_group *group;
static DEFINE_MUTEX(iommu_probe_device_lock);
int ret;
@ -357,62 +446,30 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
goto out_unlock;
}
if (!dev_iommu_get(dev)) {
ret = -ENOMEM;
ret = iommu_init_device(dev, ops);
if (ret)
goto out_unlock;
}
if (!try_module_get(ops->owner)) {
ret = -EINVAL;
goto err_free;
}
iommu_dev = ops->probe_device(dev);
if (IS_ERR(iommu_dev)) {
ret = PTR_ERR(iommu_dev);
goto out_module_put;
}
dev->iommu->iommu_dev = iommu_dev;
dev->iommu->max_pasids = dev_iommu_get_max_pasids(dev);
if (ops->is_attach_deferred)
dev->iommu->attach_deferred = ops->is_attach_deferred(dev);
group = ops->device_group(dev);
if (WARN_ON_ONCE(group == NULL))
group = ERR_PTR(-EINVAL);
if (IS_ERR(group)) {
ret = PTR_ERR(group);
goto out_release;
}
group = dev->iommu_group;
ret = iommu_group_add_device(group, dev);
mutex_lock(&group->mutex);
if (ret)
goto err_put_group;
mutex_lock(&group->mutex);
if (group_list && !group->default_domain && list_empty(&group->entry))
list_add_tail(&group->entry, group_list);
mutex_unlock(&group->mutex);
iommu_group_put(group);
mutex_unlock(&iommu_probe_device_lock);
iommu_device_link(iommu_dev, dev);
iommu_device_link(dev->iommu->iommu_dev, dev);
return 0;
err_put_group:
iommu_deinit_device(dev);
mutex_unlock(&group->mutex);
iommu_group_put(group);
out_release:
if (ops->release_device)
ops->release_device(dev);
out_module_put:
module_put(ops->owner);
err_free:
dev_iommu_free(dev);
out_unlock:
mutex_unlock(&iommu_probe_device_lock);
@ -491,63 +548,45 @@ static void __iommu_group_free_device(struct iommu_group *group,
kfree(grp_dev->name);
kfree(grp_dev);
dev->iommu_group = NULL;
}
/*
* Remove the iommu_group from the struct device. The attached group must be put
* by the caller after releaseing the group->mutex.
*/
/* Remove the iommu_group from the struct device. */
static void __iommu_group_remove_device(struct device *dev)
{
struct iommu_group *group = dev->iommu_group;
struct group_device *device;
lockdep_assert_held(&group->mutex);
mutex_lock(&group->mutex);
for_each_group_device(group, device) {
if (device->dev != dev)
continue;
list_del(&device->list);
__iommu_group_free_device(group, device);
/* Caller must put iommu_group */
return;
if (dev->iommu && dev->iommu->iommu_dev)
iommu_deinit_device(dev);
else
dev->iommu_group = NULL;
goto out;
}
WARN(true, "Corrupted iommu_group device_list");
out:
mutex_unlock(&group->mutex);
/* Pairs with the get in iommu_group_add_device() */
iommu_group_put(group);
}
static void iommu_release_device(struct device *dev)
{
struct iommu_group *group = dev->iommu_group;
const struct iommu_ops *ops;
if (!dev->iommu || !group)
return;
iommu_device_unlink(dev->iommu->iommu_dev, dev);
mutex_lock(&group->mutex);
__iommu_group_remove_device(dev);
/*
* release_device() must stop using any attached domain on the device.
* If there are still other devices in the group they are not effected
* by this callback.
*
* The IOMMU driver must set the device to either an identity or
* blocking translation and stop using any domain pointer, as it is
* going to be freed.
*/
ops = dev_iommu_ops(dev);
if (ops->release_device)
ops->release_device(dev);
mutex_unlock(&group->mutex);
/* Pairs with the get in iommu_group_add_device() */
iommu_group_put(group);
module_put(ops->owner);
dev_iommu_free(dev);
}
static int __init iommu_set_def_domain_type(char *str)
@ -808,10 +847,9 @@ static void iommu_group_release(struct kobject *kobj)
ida_free(&iommu_group_ida, group->id);
if (group->default_domain)
iommu_domain_free(group->default_domain);
if (group->blocking_domain)
iommu_domain_free(group->blocking_domain);
/* Domains are free'd by iommu_deinit_device() */
WARN_ON(group->default_domain);
WARN_ON(group->blocking_domain);
kfree(group->name);
kfree(group);
@ -1109,12 +1147,7 @@ void iommu_group_remove_device(struct device *dev)
dev_info(dev, "Removing from iommu group %d\n", group->id);
mutex_lock(&group->mutex);
__iommu_group_remove_device(dev);
mutex_unlock(&group->mutex);
/* Pairs with the get in iommu_group_add_device() */
iommu_group_put(group);
}
EXPORT_SYMBOL_GPL(iommu_group_remove_device);