Following the recent refactor of virtio notfiers [1], more specifically the patch 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. Since vhost-scsi uses the legacy interface, this value is not updated.
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 module 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 --- hw/scsi/vhost-scsi.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c index 5b26946..1c6e6d4 100644 --- a/hw/scsi/vhost-scsi.c +++ b/hw/scsi/vhost-scsi.c @@ -95,6 +95,7 @@ static int vhost_scsi_start(VHostSCSI *s) if (ret < 0) { return ret; } + VIRTIO_BUS(qbus)->ioeventfd_started = true; s->dev.acked_features = vdev->guest_features; ret = vhost_dev_start(&s->dev, vdev); @@ -152,6 +153,7 @@ static void vhost_scsi_stop(VHostSCSI *s) vhost_scsi_clear_endpoint(s); vhost_dev_stop(&s->dev, vdev); vhost_dev_disable_notifiers(&s->dev, vdev); + VIRTIO_BUS(qbus)->ioeventfd_started = false; } static uint64_t vhost_scsi_get_features(VirtIODevice *vdev, -- 1.9.4
