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vfio: Delete the unbound_list

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commit 60720a0fc6 ("vfio: Add device tracking during unbind") added the
unbound list to plug a problem with KVM where KVM_DEV_VFIO_GROUP_DEL
relied on vfio_group_get_external_user() succeeding to return the
vfio_group from a group file descriptor. The unbound list allowed
vfio_group_get_external_user() to continue to succeed in edge cases.

However commit 5d6dee80a1 ("vfio: New external user group/file match")
deleted the call to vfio_group_get_external_user() during
KVM_DEV_VFIO_GROUP_DEL. Instead vfio_external_group_match_file() is used
to directly match the file descriptor to the group pointer.

This in turn avoids the call down to vfio_dev_viable() during
KVM_DEV_VFIO_GROUP_DEL and also avoids the trouble the first commit was
trying to fix.

There are no other users of vfio_dev_viable() that care about the time
after vfio_unregister_group_dev() returns, so simply delete the
unbound_list entirely.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20220418005000.897664-10-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Jason Gunthorpe 2022-04-18 08:49:58 +08:00 committed by Joerg Roedel
parent 31076af0cb
commit 93219ea943
1 changed files with 2 additions and 72 deletions
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74
drivers/vfio/vfio.c
View File

@ -62,11 +62,6 @@ struct vfio_container {
bool noiommu;
};
struct vfio_unbound_dev {
struct device *dev;
struct list_head unbound_next;
};
struct vfio_group {
struct device dev;
struct cdev cdev;
@ -79,8 +74,6 @@ struct vfio_group {
struct notifier_block nb;
struct list_head vfio_next;
struct list_head container_next;
struct list_head unbound_list;
struct mutex unbound_lock;
atomic_t opened;
wait_queue_head_t container_q;
enum vfio_group_type type;
@ -340,16 +333,8 @@ vfio_group_get_from_iommu(struct iommu_group *iommu_group)
static void vfio_group_release(struct device *dev)
{
struct vfio_group *group = container_of(dev, struct vfio_group, dev);
struct vfio_unbound_dev *unbound, *tmp;
list_for_each_entry_safe(unbound, tmp,
&group->unbound_list, unbound_next) {
list_del(&unbound->unbound_next);
kfree(unbound);
}
mutex_destroy(&group->device_lock);
mutex_destroy(&group->unbound_lock);
iommu_group_put(group->iommu_group);
ida_free(&vfio.group_ida, MINOR(group->dev.devt));
kfree(group);
@ -381,8 +366,6 @@ static struct vfio_group *vfio_group_alloc(struct iommu_group *iommu_group,
refcount_set(&group->users, 1);
INIT_LIST_HEAD(&group->device_list);
mutex_init(&group->device_lock);
INIT_LIST_HEAD(&group->unbound_list);
mutex_init(&group->unbound_lock);
init_waitqueue_head(&group->container_q);
group->iommu_group = iommu_group;
/* put in vfio_group_release() */
@ -571,19 +554,8 @@ static int vfio_dev_viable(struct device *dev, void *data)
struct vfio_group *group = data;
struct vfio_device *device;
struct device_driver *drv = READ_ONCE(dev->driver);
struct vfio_unbound_dev *unbound;
int ret = -EINVAL;
mutex_lock(&group->unbound_lock);
list_for_each_entry(unbound, &group->unbound_list, unbound_next) {
if (dev == unbound->dev) {
ret = 0;
break;
}
}
mutex_unlock(&group->unbound_lock);
if (!ret || !drv || vfio_dev_driver_allowed(dev, drv))
if (!drv || vfio_dev_driver_allowed(dev, drv))
return 0;
device = vfio_group_get_device(group, dev);
@ -592,7 +564,7 @@ static int vfio_dev_viable(struct device *dev, void *data)
return 0;
}
return ret;
return -EINVAL;
}
/*
@ -634,7 +606,6 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb,
{
struct vfio_group *group = container_of(nb, struct vfio_group, nb);
struct device *dev = data;
struct vfio_unbound_dev *unbound;
switch (action) {
case IOMMU_GROUP_NOTIFY_ADD_DEVICE:
@ -663,28 +634,6 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb,
__func__, iommu_group_id(group->iommu_group),
dev->driver->name);
break;
case IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER:
dev_dbg(dev, "%s: group %d unbound from driver\n", __func__,
iommu_group_id(group->iommu_group));
/*
* XXX An unbound device in a live group is ok, but we'd
* really like to avoid the above BUG_ON by preventing other
* drivers from binding to it. Once that occurs, we have to
* stop the system to maintain isolation. At a minimum, we'd
* want a toggle to disable driver auto probe for this device.
*/
mutex_lock(&group->unbound_lock);
list_for_each_entry(unbound,
&group->unbound_list, unbound_next) {
if (dev == unbound->dev) {
list_del(&unbound->unbound_next);
kfree(unbound);
break;
}
}
mutex_unlock(&group->unbound_lock);
break;
}
return NOTIFY_OK;
}
@ -889,29 +838,10 @@ static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group,
void vfio_unregister_group_dev(struct vfio_device *device)
{
struct vfio_group *group = device->group;
struct vfio_unbound_dev *unbound;
unsigned int i = 0;
bool interrupted = false;
long rc;
/*
* When the device is removed from the group, the group suddenly
* becomes non-viable; the device has a driver (until the unbind
* completes), but it's not present in the group. This is bad news
* for any external users that need to re-acquire a group reference
* in order to match and release their existing reference. To
* solve this, we track such devices on the unbound_list to bridge
* the gap until they're fully unbound.
*/
unbound = kzalloc(sizeof(*unbound), GFP_KERNEL);
if (unbound) {
unbound->dev = device->dev;
mutex_lock(&group->unbound_lock);
list_add(&unbound->unbound_next, &group->unbound_list);
mutex_unlock(&group->unbound_lock);
}
WARN_ON(!unbound);
vfio_device_put(device);
rc = try_wait_for_completion(&device->comp);
while (rc <= 0) {