Commit dc15f82f authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Alex Williamson
Browse files

vfio: Delete container_q 



Now that the iommu core takes care of isolation there is no race between
driver attach and container unset. Once iommu_group_release_dma_owner()
returns the device can immediately be re-used.

Remove this mechanism.

Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/0-v1-a1e8791d795b+6b-vfio_container_q_jgg@nvidia.com


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent c5e8c392

drivers/vfio/vfio.c

+0 −20
Original line number Diff line number Diff line
@@ -74,7 +74,6 @@ struct vfio_group { 
	struct list_head		vfio_next;

	struct list_head		container_next;

	atomic_t			opened;

	wait_queue_head_t		container_q;

	enum vfio_group_type		type;

	unsigned int			dev_counter;

	struct kvm			*kvm;
@@ -363,7 +362,6 @@ 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_waitqueue_head(&group->container_q);

	group->iommu_group = iommu_group;

	/* put in vfio_group_release() */

	iommu_group_ref_get(iommu_group);
@@ -684,23 +682,6 @@ void vfio_unregister_group_dev(struct vfio_device *device) 
	group->dev_counter--;

	mutex_unlock(&group->device_lock);



	/*

	 * In order to support multiple devices per group, devices can be

	 * plucked from the group while other devices in the group are still

	 * in use.  The container persists with this group and those remaining

	 * devices still attached.  If the user creates an isolation violation

	 * by binding this device to another driver while the group is still in

	 * use, that's their fault.  However, in the case of removing the last,

	 * or potentially the only, device in the group there can be no other

	 * in-use devices in the group.  The user has done their due diligence

	 * and we should lay no claims to those devices.  In order to do that,

	 * we need to make sure the group is detached from the container.

	 * Without this stall, we're potentially racing with a user process

	 * that may attempt to immediately bind this device to another driver.

	 */

	if (list_empty(&group->device_list))

		wait_event(group->container_q, !group->container);



	if (group->type == VFIO_NO_IOMMU || group->type == VFIO_EMULATED_IOMMU)

		iommu_group_remove_device(device->dev);
@@ -945,7 +926,6 @@ static void __vfio_group_unset_container(struct vfio_group *group) 
	iommu_group_release_dma_owner(group->iommu_group);



	group->container = NULL;

	wake_up(&group->container_q);

	list_del(&group->container_next);



	/* Detaching the last group deprivileges a container, remove iommu */