From: Felipe Franciosi <[email protected]> Following the recent refactoring of virtio notifiers [1], more specifically the patch ed08a2a0b ("virtio: use virtio_bus_set_host_notifier to start/stop ioeventfd") that uses virtio_bus_set_host_notifier [2] by default, core virtio code requires 'ioeventfd_started' to be set to true/false when the host notifiers are configured. Because not all vhost devices were update (eg. vhost-scsi) to use the new interface, this value is always set to false.
When booting a guest with a vhost-scsi backend controller, SeaBIOS will initially configure the device which sets all notifiers. The guest will continue to boot fine until the kernel virtio-scsi driver reinitialises the device causing a stop followed by another start. Since ioeventfd_started was never set to true, the 'stop' operation triggered by virtio_bus_set_host_notifier() will not result in a call to virtio_pci_ioeventfd_assign(assign=false). This leaves the memory regions with stale notifiers and results on the next start triggering the following assertion: kvm_mem_ioeventfd_add: error adding ioeventfd: File exists Aborted This patch updates ioeventfd_started whenever the notifiers are set or cleared, fixing this issue. Signed-off-by: Felipe Franciosi <[email protected]> [1] http://lists.nongnu.org/archive/html/qemu-devel/2016-10/msg07748.html [2] http://lists.nongnu.org/archive/html/qemu-devel/2016-10/msg07760.html Fixes: ed08a2a0b ("virtio: use virtio_bus_set_host_notifier to start/stop ioeventfd") Reviewed-by: Michael S. Tsirkin <[email protected]> Signed-off-by: Michael S. Tsirkin <[email protected]> Tested-by: Christian Borntraeger <[email protected]> --- hw/virtio/vhost.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 131f164..1290963 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -1205,6 +1205,7 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev) goto fail_vq; } } + VIRTIO_BUS(qbus)->ioeventfd_started = true; return 0; fail_vq: @@ -1239,6 +1240,7 @@ void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev) } assert (r >= 0); } + VIRTIO_BUS(qbus)->ioeventfd_started = false; virtio_device_start_ioeventfd(vdev); } -- MST
