diff options
Diffstat (limited to 'hw/virtio/virtio.c')
| -rw-r--r-- | hw/virtio/virtio.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index ab516ac614..874377f37a 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -2447,6 +2447,7 @@ static void virtio_set_isr(VirtIODevice *vdev, int value) } } +/* Called within rcu_read_lock(). */ static bool virtio_split_should_notify(VirtIODevice *vdev, VirtQueue *vq) { uint16_t old, new; @@ -2483,6 +2484,7 @@ static bool vring_packed_need_event(VirtQueue *vq, bool wrap, return vring_need_event(off, new, old); } +/* Called within rcu_read_lock(). */ static bool virtio_packed_should_notify(VirtIODevice *vdev, VirtQueue *vq) { VRingPackedDescEvent e; @@ -3728,6 +3730,10 @@ static int virtio_device_start_ioeventfd_impl(VirtIODevice *vdev) VirtioBusState *qbus = VIRTIO_BUS(qdev_get_parent_bus(DEVICE(vdev))); int i, n, r, err; + /* + * Batch all the host notifiers in a single transaction to avoid + * quadratic time complexity in address_space_update_ioeventfds(). + */ memory_region_transaction_begin(); for (n = 0; n < VIRTIO_QUEUE_MAX; n++) { VirtQueue *vq = &vdev->vq[n]; @@ -3766,6 +3772,10 @@ assign_error: r = virtio_bus_set_host_notifier(qbus, n, false); assert(r >= 0); } + /* + * The transaction expects the ioeventfds to be open when it + * commits. Do it now, before the cleanup loop. + */ memory_region_transaction_commit(); while (--i >= 0) { @@ -3790,6 +3800,10 @@ static void virtio_device_stop_ioeventfd_impl(VirtIODevice *vdev) VirtioBusState *qbus = VIRTIO_BUS(qdev_get_parent_bus(DEVICE(vdev))); int n, r; + /* + * Batch all the host notifiers in a single transaction to avoid + * quadratic time complexity in address_space_update_ioeventfds(). + */ memory_region_transaction_begin(); for (n = 0; n < VIRTIO_QUEUE_MAX; n++) { VirtQueue *vq = &vdev->vq[n]; @@ -3801,6 +3815,10 @@ static void virtio_device_stop_ioeventfd_impl(VirtIODevice *vdev) r = virtio_bus_set_host_notifier(qbus, n, false); assert(r >= 0); } + /* + * The transaction expects the ioeventfds to be open when it + * commits. Do it now, before the cleanup loop. + */ memory_region_transaction_commit(); for (n = 0; n < VIRTIO_QUEUE_MAX; n++) { |