On Thu, 2011-02-03 at 11:47 +0530, Amit Shah wrote:
> Add a compat property for older machine types. When this is used (via
> -M pc-0.13, for example), the new flow control mechanisms will not be
> used. This is done to keep migration from a machine started with older
> type on a pc-0.14+ qemu to an older machine working.
>
> The property is named 'flow_control' and defaults to on.
>
> Reported-by: Alex Williamson <alex.william...@redhat.com>
> Signed-off-by: Amit Shah <amit.s...@redhat.com>
> ---
> hw/pc_piix.c | 16 ++++++++++
> hw/virtio-pci.c | 2 +
> hw/virtio-serial-bus.c | 77
> +++++++++++++++++++++++++++++++++++++++++-------
> hw/virtio-serial.h | 12 +++++++
> 4 files changed, 96 insertions(+), 11 deletions(-)
Acked-by: Alex Williamson <alex.william...@redhat.com>
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 7b74473..05b0449 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -243,6 +243,10 @@ static QEMUMachine pc_machine_v0_13 = {
> .driver = "PCI",
> .property = "command_serr_enable",
> .value = "off",
> + },{
> + .driver = "virtio-serial-pci",
> + .property = "flow_control",
> + .value = stringify(0),
> },
> { /* end of list */ }
> },
> @@ -263,6 +267,10 @@ static QEMUMachine pc_machine_v0_12 = {
> .property = "vectors",
> .value = stringify(0),
> },{
> + .driver = "virtio-serial-pci",
> + .property = "flow_control",
> + .value = stringify(0),
> + },{
> .driver = "VGA",
> .property = "rombar",
> .value = stringify(0),
> @@ -298,6 +306,10 @@ static QEMUMachine pc_machine_v0_11 = {
> .property = "vectors",
> .value = stringify(0),
> },{
> + .driver = "virtio-serial-pci",
> + .property = "flow_control",
> + .value = stringify(0),
> + },{
> .driver = "ide-drive",
> .property = "ver",
> .value = "0.11",
> @@ -341,6 +353,10 @@ static QEMUMachine pc_machine_v0_10 = {
> .property = "vectors",
> .value = stringify(0),
> },{
> + .driver = "virtio-serial-pci",
> + .property = "flow_control",
> + .value = stringify(0),
> + },{
> .driver = "virtio-net-pci",
> .property = "vectors",
> .value = stringify(0),
> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
> index 952b5d2..530ce9d 100644
> --- a/hw/virtio-pci.c
> +++ b/hw/virtio-pci.c
> @@ -904,6 +904,8 @@ static PCIDeviceInfo virtio_info[] = {
> DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
> DEFINE_PROP_UINT32("max_ports", VirtIOPCIProxy,
> serial.max_virtserial_ports, 31),
> + DEFINE_PROP_UINT32("flow_control", VirtIOPCIProxy,
> + serial.flow_control, 1),
> DEFINE_PROP_END_OF_LIST(),
> },
> .qdev.reset = virtio_pci_reset,
> diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
> index 1753785..f681646 100644
> --- a/hw/virtio-serial-bus.c
> +++ b/hw/virtio-serial-bus.c
> @@ -49,6 +49,8 @@ struct VirtIOSerial {
> uint32_t *ports_map;
>
> struct virtio_console_config config;
> +
> + bool flow_control;
> };
>
> static VirtIOSerialPort *find_port_by_id(VirtIOSerial *vser, uint32_t id)
> @@ -123,12 +125,46 @@ static void discard_vq_data(VirtQueue *vq, VirtIODevice
> *vdev)
> virtio_notify(vdev, vq);
> }
>
> +static void do_flush_queued_data_no_flow_control(VirtIOSerialPort *port,
> + VirtQueue *vq,
> + VirtIODevice *vdev)
> +{
> + VirtQueueElement elem;
> +
> + while (!port->throttled && virtqueue_pop(vq, &elem)) {
> + uint8_t *buf;
> + size_t ret, buf_size;
> +
> + buf_size = iov_size(elem.out_sg, elem.out_num);
> + buf = qemu_malloc(buf_size);
> + ret = iov_to_buf(elem.out_sg, elem.out_num, buf, 0, buf_size);
> +
> + /*
> + * have_data has been modified to return the number of bytes
> + * successfully consumed. We can't act upon that information
> + * in the no-flow-control implementation, so we'll discard it
> + * here. No callers currently use flow control, but they
> + * should take this into account for backward compatibility.
> + */
> + port->info->have_data(port, buf, ret);
> + qemu_free(buf);
> +
> + virtqueue_push(vq, &elem, 0);
> + }
> + virtio_notify(vdev, vq);
> +}
> +
> static void do_flush_queued_data(VirtIOSerialPort *port, VirtQueue *vq,
> VirtIODevice *vdev)
> {
> assert(port);
> assert(virtio_queue_ready(vq));
>
> + if (!virtio_serial_flow_control_enabled(port)) {
> + do_flush_queued_data_no_flow_control(port, vq, vdev);
> + return;
> + }
> +
> while (!port->throttled) {
> unsigned int i;
>
> @@ -296,6 +332,15 @@ void virtio_serial_throttle_port(VirtIOSerialPort *port,
> bool throttle)
> flush_queued_data(port);
> }
>
> +bool virtio_serial_flow_control_enabled(VirtIOSerialPort *port)
> +{
> + if (!port) {
> + return false;
> + }
> +
> + return port->vser->flow_control;
> +}
> +
> /* Guest wants to notify us of some event */
> static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len)
> {
> @@ -533,17 +578,19 @@ static void virtio_serial_save(QEMUFile *f, void
> *opaque)
> qemu_put_byte(f, port->guest_connected);
> qemu_put_byte(f, port->host_connected);
>
> - elem_popped = 0;
> - if (port->elem.out_num) {
> - elem_popped = 1;
> - }
> - qemu_put_be32s(f, &elem_popped);
> - if (elem_popped) {
> - qemu_put_be32s(f, &port->iov_idx);
> - qemu_put_be64s(f, &port->iov_offset);
> + if (virtio_serial_flow_control_enabled(port)) {
> + elem_popped = 0;
> + if (port->elem.out_num) {
> + elem_popped = 1;
> + }
> + qemu_put_be32s(f, &elem_popped);
> + if (elem_popped) {
> + qemu_put_be32s(f, &port->iov_idx);
> + qemu_put_be64s(f, &port->iov_offset);
>
> - qemu_put_buffer(f, (unsigned char *)&port->elem,
> - sizeof(port->elem));
> + qemu_put_buffer(f, (unsigned char *)&port->elem,
> + sizeof(port->elem));
> + }
> }
> }
> }
> @@ -816,6 +863,7 @@ VirtIODevice *virtio_serial_init(DeviceState *dev,
> virtio_serial_conf *conf)
> VirtIOSerial *vser;
> VirtIODevice *vdev;
> uint32_t i, max_supported_ports;
> + unsigned int savevm_ver;
>
> if (!conf->max_virtserial_ports)
> return NULL;
> @@ -881,11 +929,18 @@ VirtIODevice *virtio_serial_init(DeviceState *dev,
> virtio_serial_conf *conf)
>
> vser->qdev = dev;
>
> + vser->flow_control = true;
> + savevm_ver = 3;
> + if (!conf->flow_control) {
> + vser->flow_control = false;
> + savevm_ver = 2;
> + }
> +
> /*
> * Register for the savevm section with the virtio-console name
> * to preserve backward compat
> */
> - register_savevm(dev, "virtio-console", -1, 3, virtio_serial_save,
> + register_savevm(dev, "virtio-console", -1, savevm_ver,
> virtio_serial_save,
> virtio_serial_load, vser);
>
> return vdev;
> diff --git a/hw/virtio-serial.h b/hw/virtio-serial.h
> index de624c3..57d2dee 100644
> --- a/hw/virtio-serial.h
> +++ b/hw/virtio-serial.h
> @@ -48,6 +48,13 @@ struct virtio_console_control {
> struct virtio_serial_conf {
> /* Max. number of ports we can have for a the virtio-serial device */
> uint32_t max_virtserial_ports;
> +
> + /*
> + * Should this device behave the way it did in prior to pc-0.14
> + * (ie. no flow control)? This will be necessary to allow
> + * migrations from a pre-0.14-machine type to older qemu code
> + */
> + uint32_t flow_control;
> };
>
> /* Some events for the internal messages (control packets) */
> @@ -204,4 +211,9 @@ size_t virtio_serial_guest_ready(VirtIOSerialPort *port);
> */
> void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle);
>
> +/*
> + * Does this machine type disable the use of flow control?
> + */
> +bool virtio_serial_flow_control_enabled(VirtIOSerialPort *port);
> +
> #endif
