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(-)
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
--
1.7.3.5
