diff options
| -rw-r--r-- | hw/char/virtio-serial-bus.c | 31 | ||||
| -rw-r--r-- | include/hw/virtio/virtio-serial.h | 11 |
2 files changed, 42 insertions, 0 deletions
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c index c86814f059..d14e872d34 100644 --- a/hw/char/virtio-serial-bus.c +++ b/hw/char/virtio-serial-bus.c @@ -465,6 +465,37 @@ static void handle_output(VirtIODevice *vdev, VirtQueue *vq) static void handle_input(VirtIODevice *vdev, VirtQueue *vq) { + /* + * Users of virtio-serial would like to know when guest becomes + * writable again -- i.e. if a vq had stuff queued up and the + * guest wasn't reading at all, the host would not be able to + * write to the vq anymore. Once the guest reads off something, + * we can start queueing things up again. However, this call is + * made for each buffer addition by the guest -- even though free + * buffers existed prior to the current buffer addition. This is + * done so as not to maintain previous state, which will need + * additional live-migration-related changes. + */ + VirtIOSerial *vser; + VirtIOSerialPort *port; + VirtIOSerialPortClass *vsc; + + vser = VIRTIO_SERIAL(vdev); + port = find_port_by_vq(vser, vq); + + if (!port) { + return; + } + vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port); + + /* + * If guest_connected is false, this call is being made by the + * early-boot queueing up of descriptors, which is just noise for + * the host apps -- don't disturb them in that case. + */ + if (port->guest_connected && port->host_connected && vsc->guest_writable) { + vsc->guest_writable(port); + } } static uint32_t get_features(VirtIODevice *vdev, uint32_t features) diff --git a/include/hw/virtio/virtio-serial.h b/include/hw/virtio/virtio-serial.h index ccf8459829..18d1bccd0b 100644 --- a/include/hw/virtio/virtio-serial.h +++ b/include/hw/virtio/virtio-serial.h @@ -60,6 +60,17 @@ typedef struct VirtIOSerialPortClass { /* Guest is now ready to accept data (virtqueues set up). */ void (*guest_ready)(VirtIOSerialPort *port); + /* + * Guest has enqueued a buffer for the host to write into. + * Called each time a buffer is enqueued by the guest; + * irrespective of whether there already were free buffers the + * host could have consumed. + * + * This is dependent on both the guest and host end being + * connected. + */ + void (*guest_writable)(VirtIOSerialPort *port); + /* * Guest wrote some data to the port. This data is handed over to * the app via this callback. The app can return a size less than |