Commit 21c13829 authored by Jason Gunthorpe's avatar Jason Gunthorpe Committed by Alex Williamson
Browse files

vfio: Remove vfio_group dev_counter 



This counts the number of devices attached to a vfio_group, ie the number
of items in the group->device_list.

It is only read in vfio_pin_pages(), as some kind of protection against
limitations in type1.

However, with all the code cleanups in this area, now that
vfio_pin_pages() accepts a vfio_device directly it is redundant.  All
drivers are already calling vfio_register_emulated_iommu_dev() which
directly creates a group specifically for the device and thus it is
guaranteed that there is a singleton group.

Leave a note in the comment about this requirement and remove the logic.

Reviewed-by: default avatarYi Liu <yi.l.liu@intel.com>
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-v2-d4374a7bf0c9+c4-vfio_dev_counter_jgg@nvidia.com


Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
parent 453e6c98

drivers/vfio/vfio_main.c

+3 −6
Original line number Diff line number Diff line
@@ -75,7 +75,6 @@ struct vfio_group { 
	struct list_head		vfio_next;

	struct list_head		container_next;

	enum vfio_group_type		type;

	unsigned int			dev_counter;

	struct rw_semaphore		group_rwsem;

	struct kvm			*kvm;

	struct file			*opened_file;
@@ -609,7 +608,6 @@ static int __vfio_register_dev(struct vfio_device *device, 


	mutex_lock(&group->device_lock);

	list_add(&device->group_next, &group->device_list);

	group->dev_counter++;

	mutex_unlock(&group->device_lock);



	return 0;
@@ -697,7 +695,6 @@ void vfio_unregister_group_dev(struct vfio_device *device) 


	mutex_lock(&group->device_lock);

	list_del(&device->group_next);

	group->dev_counter--;

	mutex_unlock(&group->device_lock);



	if (group->type == VFIO_NO_IOMMU || group->type == VFIO_EMULATED_IOMMU)
@@ -1991,6 +1988,9 @@ EXPORT_SYMBOL(vfio_set_irqs_validate_and_prepare); 
 * @prot [in]    : protection flags

 * @pages[out]   : array of host pages

 * Return error or number of pages pinned.

 *

 * A driver may only call this function if the vfio_device was created

 * by vfio_register_emulated_iommu_dev().

 */

int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova,

		   int npage, int prot, struct page **pages)
@@ -2006,9 +2006,6 @@ int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova, 
	if (npage > VFIO_PIN_PAGES_MAX_ENTRIES)

		return -E2BIG;



	if (group->dev_counter > 1)

		return -EINVAL;



	/* group->container cannot change while a vfio device is open */

	container = group->container;

	driver = container->iommu_driver;