We should guarantee that RAM will not be modified while VM has a stopped
state, otherwise it can lead to negative consequences during post-copy
migration. In RUN_STATE_FINISH_MIGRATE step, it's expected that RAM on
source side will not be modified as this could lead to non-consistent
vm state
on the destination side. Also RAM access during postcopy-ram migration
with
enabled release-ram capability can lead to sad consequences.
Let's add enable_backend() callback to avoid undesirable virtioqueue
changes
in the guest memory.
Signed-off-by: Pavel Butsykin <pbutsy...@virtuozzo.com>
---
hw/char/virtio-console.c | 21 +++++++++++++++++++++
hw/char/virtio-serial-bus.c | 7 +++++++
include/hw/virtio/virtio-serial.h | 3 +++
3 files changed, 31 insertions(+)
diff --git a/hw/char/virtio-console.c b/hw/char/virtio-console.c
index 0cb1668c8a..b55905892e 100644
--- a/hw/char/virtio-console.c
+++ b/hw/char/virtio-console.c
@@ -163,6 +163,26 @@ static void chr_event(void *opaque, int event)
}
}
+static void virtconsole_enable_backend(VirtIOSerialPort *port, bool
enable)
+{
+ VirtConsole *vcon = VIRTIO_CONSOLE(port);
+
+ if (!qemu_chr_fe_get_driver(&vcon->chr)) {
+ return;
+ }
+
+ if (enable) {
+ VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
+
+ qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
+ k->is_console ? NULL : chr_event,
+ vcon, NULL, false);
+ } else {
+ qemu_chr_fe_set_handlers(&vcon->chr, NULL, NULL,
+ NULL, NULL, NULL, false);
+ }
+}
+
static void virtconsole_realize(DeviceState *dev, Error **errp)
{
VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
@@ -233,6 +253,7 @@ static void virtserialport_class_init(ObjectClass
*klass, void *data)
k->unrealize = virtconsole_unrealize;
k->have_data = flush_buf;
k->set_guest_connected = set_guest_connected;
+ k->enable_backend = virtconsole_enable_backend;
k->guest_writable = guest_writable;
dc->props = virtserialport_properties;
}
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index f5bc173844..f0f18c8e7c 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -637,6 +637,13 @@ static void set_status(VirtIODevice *vdev,
uint8_t status)
if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
guest_reset(vser);
}
+
+ QTAILQ_FOREACH(port, &vser->ports, next) {
+ VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
+ if (vsc->enable_backend) {
+ vsc->enable_backend(port, vdev->vm_running);
+ }
+ }
}
static void vser_reset(VirtIODevice *vdev)
diff --git a/include/hw/virtio/virtio-serial.h
b/include/hw/virtio/virtio-serial.h
index b19c44727f..12657a9f39 100644
--- a/include/hw/virtio/virtio-serial.h
+++ b/include/hw/virtio/virtio-serial.h
@@ -58,6 +58,9 @@ typedef struct VirtIOSerialPortClass {
/* Guest opened/closed device. */
void (*set_guest_connected)(VirtIOSerialPort *port, int
guest_connected);
+ /* Enable/disable backend for virtio serial port */
+ void (*enable_backend)(VirtIOSerialPort *port, bool enable);
+
/* Guest is now ready to accept data (virtqueues set up). */
void (*guest_ready)(VirtIOSerialPort *port);