vfio: add local lock for virqfd instead of depending on VFIO PCI

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>
Reviewed-by: Eric Auger <eric.auger@linaro.org>
Tested-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index fa033c3..de06979 100644 (file)
--- 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;