From 55289fb036481396466d7825fa01d829c891108c Mon Sep 17 00:00:00 2001 From: Pavel Butsykin Date: Tue, 19 Sep 2017 15:07:33 +0300 Subject: virtio-serial: add enable_backend callback 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 Message-Id: <20170919120733.22020-1-pbutsykin@virtuozzo.com> Signed-off-by: Paolo Bonzini --- hw/char/virtio-console.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'hw/char/virtio-console.c') diff --git a/hw/char/virtio-console.c b/hw/char/virtio-console.c index 198b2a89c0..172c72d06c 100644 --- a/hw/char/virtio-console.c +++ b/hw/char/virtio-console.c @@ -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; } -- cgit v1.2.3