[PATCH v14 16/20] vfio: add local lock for virqfd instead of depending on VFIO PCI

Baptiste Reynal
2015-03-02T17:03:11Z

The Virqfd code needs to keep accesses to any struct *virqfd safe, but
this comes into play only when creating or destroying eventfds, so sharing
the same spinlock with the VFIO bus driver is not necessary.

Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Signed-off-by: Baptiste Reynal <b.reynal@virtualopensystems.com>
---
drivers/vfio/pci/vfio_pci_intrs.c | 31 ++++++++++++++++---------------
1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index d96ffe0..7d3c135 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -44,6 +44,7 @@ struct virqfd {
};

static struct workqueue_struct *vfio_irqfd_cleanup_wq;
+DEFINE_SPINLOCK(virqfd_lock);

int __init vfio_virqfd_init(void)
{
@@ -80,21 +81,21 @@ static int virqfd_wakeup(wait_queue_t *wait, unsigned mode, int sync, void *key)

if (flags & POLLHUP) {
unsigned long flags;
- spin_lock_irqsave(&virqfd->vdev->irqlock, flags);
+ spin_lock_irqsave(&virqfd_lock, 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
+ * virqfd 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.
+ * going away because we hold the lock to get here.
*/
if (*(virqfd->pvirqfd) == virqfd) {
*(virqfd->pvirqfd) = NULL;
virqfd_deactivate(virqfd);
}

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

return 0;
@@ -170,16 +171,16 @@ int vfio_virqfd_enable(struct vfio_pci_device *vdev,
* we update the pointer to the virqfd under lock to avoid
* pushing multiple jobs to release the same virqfd.
*/
- spin_lock_irq(&vdev->irqlock);
+ spin_lock_irq(&virqfd_lock);

if (*pvirqfd) {
- spin_unlock_irq(&vdev->irqlock);
+ spin_unlock_irq(&virqfd_lock);
ret = -EBUSY;
goto err_busy;
}
*pvirqfd = virqfd;

- spin_unlock_irq(&vdev->irqlock);
+ spin_unlock_irq(&virqfd_lock);

/*
* Install our own custom wake-up handling so we are notified via
@@ -217,18 +218,18 @@ err_fd:
}
EXPORT_SYMBOL_GPL(vfio_virqfd_enable);

-void vfio_virqfd_disable(struct vfio_pci_device *vdev, struct virqfd **pvirqfd)
+void vfio_virqfd_disable(struct virqfd **pvirqfd)
{
unsigned long flags;

- spin_lock_irqsave(&vdev->irqlock, flags);
+ spin_lock_irqsave(&virqfd_lock, flags);

if (*pvirqfd) {
virqfd_deactivate(*pvirqfd);
*pvirqfd = NULL;
}

- spin_unlock_irqrestore(&vdev->irqlock, flags);
+ spin_unlock_irqrestore(&virqfd_lock, flags);

/*
* Block until we know all outstanding shutdown jobs have completed.
@@ -441,8 +442,8 @@ 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);
- vfio_virqfd_disable(vdev, &vdev->ctx[0].unmask);
- vfio_virqfd_disable(vdev, &vdev->ctx[0].mask);
+ vfio_virqfd_disable(&vdev->ctx[0].unmask);
+ vfio_virqfd_disable(&vdev->ctx[0].mask);
vdev->irq_type = VFIO_PCI_NUM_IRQS;
vdev->num_ctx = 0;
kfree(vdev->ctx);
@@ -606,8 +607,8 @@ 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++) {
- vfio_virqfd_disable(vdev, &vdev->ctx[i].unmask);
- vfio_virqfd_disable(vdev, &vdev->ctx[i].mask);
+ vfio_virqfd_disable(&vdev->ctx[i].unmask);
+ vfio_virqfd_disable(&vdev->ctx[i].mask);
}

if (msix) {
@@ -645,7 +646,7 @@ static int vfio_pci_set_intx_unmask(struct vfio_pci_device *vdev,
vfio_send_intx_eventfd, NULL,
&vdev->ctx[0].unmask, fd);

- vfio_virqfd_disable(vdev, &vdev->ctx[0].unmask);
+ vfio_virqfd_disable(&vdev->ctx[0].unmask);
}

return 0;
--
2.3.1