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Commit 3df765fc authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'vfio-v3.11-rc4' of git://github.com/awilliam/linux-vfio 

Pull vfio fixes from Alex Williamson:
 "misc fixes around overreacting to bus notifier events and a locking
  fix for a corner case blocked remove"

* tag 'vfio-v3.11-rc4' of git://github.com/awilliam/linux-vfio:
  vfio-pci: Avoid deadlock on remove
  vfio: Ignore sprurious notifies
  vfio: Don't overreact to DEL_DEVICE
parents 19788a90 d24cdbfd

drivers/vfio/pci/vfio_pci.c

+21 −2
Original line number Diff line number Diff line
@@ -137,8 +137,27 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev) 
	 */

	pci_write_config_word(pdev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);



	if (vdev->reset_works)

		__pci_reset_function(pdev);

	/*

	 * Careful, device_lock may already be held.  This is the case if

	 * a driver unbind is blocked.  Try to get the locks ourselves to

	 * prevent a deadlock.

	 */

	if (vdev->reset_works) {

		bool reset_done = false;



		if (pci_cfg_access_trylock(pdev)) {

			if (device_trylock(&pdev->dev)) {

				__pci_reset_function_locked(pdev);

				reset_done = true;

				device_unlock(&pdev->dev);

			}

			pci_cfg_access_unlock(pdev);

		}



		if (!reset_done)

			pr_warn("%s: Unable to acquire locks for reset of %s\n",

				__func__, dev_name(&pdev->dev));

	}



	pci_restore_state(pdev);

}

drivers/vfio/vfio.c

+10 −27
Original line number Diff line number Diff line
@@ -494,27 +494,6 @@ static int vfio_group_nb_add_dev(struct vfio_group *group, struct device *dev) 
	return 0;

}



static int vfio_group_nb_del_dev(struct vfio_group *group, struct device *dev)

{

	struct vfio_device *device;



	/*

	 * Expect to fall out here.  If a device was in use, it would

	 * have been bound to a vfio sub-driver, which would have blocked

	 * in .remove at vfio_del_group_dev.  Sanity check that we no

	 * longer track the device, so it's safe to remove.

	 */

	device = vfio_group_get_device(group, dev);

	if (likely(!device))

		return 0;



	WARN("Device %s removed from live group %d!\n", dev_name(dev),

	     iommu_group_id(group->iommu_group));



	vfio_device_put(device);

	return 0;

}



static int vfio_group_nb_verify(struct vfio_group *group, struct device *dev)

{

	/* We don't care what happens when the group isn't in use */
@@ -531,13 +510,11 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb, 
	struct device *dev = data;



	/*

	 * Need to go through a group_lock lookup to get a reference or

	 * we risk racing a group being removed.  Leave a WARN_ON for

	 * debuging, but if the group no longer exists, a spurious notify

	 * is harmless.

	 * Need to go through a group_lock lookup to get a reference or we

	 * risk racing a group being removed.  Ignore spurious notifies.

	 */

	group = vfio_group_try_get(group);

	if (WARN_ON(!group))

	if (!group)

		return NOTIFY_OK;



	switch (action) {
@@ -545,7 +522,13 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb, 
		vfio_group_nb_add_dev(group, dev);

		break;

	case IOMMU_GROUP_NOTIFY_DEL_DEVICE:

		vfio_group_nb_del_dev(group, dev);

		/*

		 * Nothing to do here.  If the device is in use, then the

		 * vfio sub-driver should block the remove callback until

		 * it is unused.  If the device is unused or attached to a

		 * stub driver, then it should be released and we don't

		 * care that it will be going away.

		 */

		break;

	case IOMMU_GROUP_NOTIFY_BIND_DRIVER:

		pr_debug("%s: Device %s, group %d binding to driver\n",