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Commit 1abbce4e authored by Linus Torvalds's avatar Linus Torvalds
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Merge tag 'vfio-for-linus' of git://github.com/awilliam/linux-vfio 

Pull vfio fixes from Alex Williamson:
 "VFIO doc update and virqfd race fix"

* tag 'vfio-for-linus' of git://github.com/awilliam/linux-vfio:
  vfio: Fix virqfd release race
  vfio: Trivial Documentation correction
parents 0c59f236 b68e7fa8

Documentation/vfio.txt

+1 −1
Original line number Diff line number Diff line
@@ -133,7 +133,7 @@ character devices for this group: 
$ lspci -n -s 0000:06:0d.0

06:0d.0 0401: 1102:0002 (rev 08)

# echo 0000:06:0d.0 > /sys/bus/pci/devices/0000:06:0d.0/driver/unbind

# echo 1102 0002 > /sys/bus/pci/drivers/vfio/new_id

# echo 1102 0002 > /sys/bus/pci/drivers/vfio-pci/new_id



Now we need to look at what other devices are in the group to free

it for use by VFIO:

drivers/vfio/pci/vfio_pci_intrs.c

+56 −20
Original line number Diff line number Diff line
@@ -76,9 +76,24 @@ static int virqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key) 
			schedule_work(&virqfd->inject);

	}



	if (flags & POLLHUP)

		/* The eventfd is closing, detach from VFIO */

	if (flags & POLLHUP) {

		unsigned long flags;

		spin_lock_irqsave(&virqfd->vdev->irqlock, flags);



		/*

		 * The eventfd is closing, if the virqfd has not yet been

		 * queued for release, as determined by testing whether the

		 * vdev pointer to it is still valid, queue it now.  As

		 * with kvm irqfds, we know we won't race against the virqfd

		 * going away because we hold wqh->lock to get here.

		 */

		if (*(virqfd->pvirqfd) == virqfd) {

			*(virqfd->pvirqfd) = NULL;

			virqfd_deactivate(virqfd);

		}



		spin_unlock_irqrestore(&virqfd->vdev->irqlock, flags);

	}



	return 0;

}
@@ -93,7 +108,6 @@ static void virqfd_ptable_queue_proc(struct file *file, 
static void virqfd_shutdown(struct work_struct *work)

{

	struct virqfd *virqfd = container_of(work, struct virqfd, shutdown);

	struct virqfd **pvirqfd = virqfd->pvirqfd;

	u64 cnt;



	eventfd_ctx_remove_wait_queue(virqfd->eventfd, &virqfd->wait, &cnt);
@@ -101,7 +115,6 @@ static void virqfd_shutdown(struct work_struct *work) 
	eventfd_ctx_put(virqfd->eventfd);



	kfree(virqfd);

	*pvirqfd = NULL;

}



static void virqfd_inject(struct work_struct *work)
@@ -122,15 +135,11 @@ static int virqfd_enable(struct vfio_pci_device *vdev, 
	int ret = 0;

	unsigned int events;



	if (*pvirqfd)

		return -EBUSY;



	virqfd = kzalloc(sizeof(*virqfd), GFP_KERNEL);

	if (!virqfd)

		return -ENOMEM;



	virqfd->pvirqfd = pvirqfd;

	*pvirqfd = virqfd;

	virqfd->vdev = vdev;

	virqfd->handler = handler;

	virqfd->thread = thread;
@@ -153,6 +162,23 @@ static int virqfd_enable(struct vfio_pci_device *vdev, 


	virqfd->eventfd = ctx;



	/*

	 * virqfds can be released by closing the eventfd or directly

	 * through ioctl.  These are both done through a workqueue, so

	 * we update the pointer to the virqfd under lock to avoid

	 * pushing multiple jobs to release the same virqfd.

	 */

	spin_lock_irq(&vdev->irqlock);



	if (*pvirqfd) {

		spin_unlock_irq(&vdev->irqlock);

		ret = -EBUSY;

		goto fail;

	}

	*pvirqfd = virqfd;



	spin_unlock_irq(&vdev->irqlock);



	/*

	 * Install our own custom wake-up handling so we are notified via

	 * a callback whenever someone signals the underlying eventfd.
@@ -187,19 +213,29 @@ static int virqfd_enable(struct vfio_pci_device *vdev, 
		fput(file);



	kfree(virqfd);

	*pvirqfd = NULL;



	return ret;

}



static void virqfd_disable(struct virqfd *virqfd)

static void virqfd_disable(struct vfio_pci_device *vdev,

			   struct virqfd **pvirqfd)

{

	if (!virqfd)

		return;

	unsigned long flags;



	virqfd_deactivate(virqfd);

	spin_lock_irqsave(&vdev->irqlock, flags);



	/* Block until we know all outstanding shutdown jobs have completed. */

	if (*pvirqfd) {

		virqfd_deactivate(*pvirqfd);

		*pvirqfd = NULL;

	}



	spin_unlock_irqrestore(&vdev->irqlock, flags);



	/*

	 * Block until we know all outstanding shutdown jobs have completed.

	 * Even if we don't queue the job, flush the wq to be sure it's

	 * been released.

	 */

	flush_workqueue(vfio_irqfd_cleanup_wq);

}
@@ -392,8 +428,8 @@ static int vfio_intx_set_signal(struct vfio_pci_device *vdev, int fd) 
static void vfio_intx_disable(struct vfio_pci_device *vdev)

{

	vfio_intx_set_signal(vdev, -1);

	virqfd_disable(vdev->ctx[0].unmask);

	virqfd_disable(vdev->ctx[0].mask);

	virqfd_disable(vdev, &vdev->ctx[0].unmask);

	virqfd_disable(vdev, &vdev->ctx[0].mask);

	vdev->irq_type = VFIO_PCI_NUM_IRQS;

	vdev->num_ctx = 0;

	kfree(vdev->ctx);
@@ -539,8 +575,8 @@ static void vfio_msi_disable(struct vfio_pci_device *vdev, bool msix) 
	vfio_msi_set_block(vdev, 0, vdev->num_ctx, NULL, msix);



	for (i = 0; i < vdev->num_ctx; i++) {

		virqfd_disable(vdev->ctx[i].unmask);

		virqfd_disable(vdev->ctx[i].mask);

		virqfd_disable(vdev, &vdev->ctx[i].unmask);

		virqfd_disable(vdev, &vdev->ctx[i].mask);

	}



	if (msix) {
@@ -577,7 +613,7 @@ static int vfio_pci_set_intx_unmask(struct vfio_pci_device *vdev, 
					     vfio_send_intx_eventfd, NULL,

					     &vdev->ctx[0].unmask, fd);



		virqfd_disable(vdev->ctx[0].unmask);

		virqfd_disable(vdev, &vdev->ctx[0].unmask);

	}



	return 0;