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VFIO doc update and virqfd race fix

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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
This commit is contained in:
Linus Torvalds 2012-09-24 16:16:33 -07:00
commit 1abbce4e83
2 changed files with 57 additions and 21 deletions
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2
Documentation/vfio.txt
View file

@ -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:

76
drivers/vfio/pci/vfio_pci_intrs.c
View file

@ -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 */
virqfd_deactivate(virqfd);
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 @@ fail:
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;