haraldwolff/qemu-patch-raspberry4
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virtio-serial: add enable_backend callback

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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 <pbutsykin@virtuozzo.com>
Message-Id: <20170919120733.22020-1-pbutsykin@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Pavel Butsykin 2017-09-19 15:07:33 +03:00 committed by Paolo Bonzini
parent b62b7ed0fc
commit 55289fb036
3 changed files with 31 additions and 0 deletions
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21
hw/char/virtio-console.c
View file

@ -187,6 +187,26 @@ static int chr_be_change(void *opaque)
return 0;
}
static void virtconsole_enable_backend(VirtIOSerialPort *port, bool enable)
{
VirtConsole *vcon = VIRTIO_CONSOLE(port);
if (!qemu_chr_fe_backend_connected(&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,
chr_be_change, vcon, NULL, false);
} else {
qemu_chr_fe_set_handlers(&vcon->chr, NULL, NULL, NULL,
NULL, NULL, NULL, false);
}
}
static void virtconsole_realize(DeviceState *dev, Error **errp)
{
VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
@ -258,6 +278,7 @@ 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;
}

7
hw/char/virtio-serial-bus.c
View file

@ -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)

3
include/hw/virtio/virtio-serial.h
View file

@ -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);