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Re: [Qemu-devel] [PATCH 2/5] virtio: Migrate the "start_on_kick" flag
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH 2/5] virtio: Migrate the "start_on_kick" flag |
Date: |
Mon, 3 Jun 2019 17:03:06 -0400 |
On Mon, Jun 03, 2019 at 10:16:39PM +0200, Greg Kurz wrote:
> On Wed, 29 May 2019 15:09:52 +0800
> address@hidden wrote:
>
> > From: Xie Yongji <address@hidden>
> >
> > We should migrate the "start_on_kick" flag so that we
> > would not miss starting device on kicking at startup
> > after migration.
> >
>
> Hmm... IIUC "start_on_kick" means "virtio 1.0 transitional device that has
> not been started yet", ie:
>
> !vdev->started &&
> (virtio_host_has_feature(vdev, VIRTIO_F_VERSION_1) &&
> !virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1))
Or a legacy device I guess?
> If so, not sure why you need this extra field in the first place, but
> you probably don't need to migrate it. Just recalculate in a post load
> callback.
>
> > Signed-off-by: Xie Yongji <address@hidden>
> > ---
> > hw/virtio/virtio.c | 19 +++++++++++++++++++
> > 1 file changed, 19 insertions(+)
> >
> > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > index fc8fca81ad..4d4ff67791 100644
> > --- a/hw/virtio/virtio.c
> > +++ b/hw/virtio/virtio.c
> > @@ -1802,6 +1802,13 @@ static bool virtio_started_needed(void *opaque)
> > return vdev->started;
> > }
> >
> > +static bool virtio_start_on_kick_needed(void *opaque)
> > +{
> > + VirtIODevice *vdev = opaque;
> > +
> > + return vdev->start_on_kick;
> > +}
> > +
> > static const VMStateDescription vmstate_virtqueue = {
> > .name = "virtqueue_state",
> > .version_id = 1,
> > @@ -1941,6 +1948,17 @@ static const VMStateDescription
> > vmstate_virtio_started = {
> > }
> > };
> >
> > +static const VMStateDescription vmstate_virtio_start_on_kick = {
> > + .name = "virtio/start_on_kick",
> > + .version_id = 1,
> > + .minimum_version_id = 1,
> > + .needed = &virtio_start_on_kick_needed,
> > + .fields = (VMStateField[]) {
> > + VMSTATE_BOOL(start_on_kick, VirtIODevice),
> > + VMSTATE_END_OF_LIST()
> > + }
> > +};
> > +
> > static const VMStateDescription vmstate_virtio = {
> > .name = "virtio",
> > .version_id = 1,
> > @@ -1957,6 +1975,7 @@ static const VMStateDescription vmstate_virtio = {
> > &vmstate_virtio_broken,
> > &vmstate_virtio_extra_state,
> > &vmstate_virtio_started,
> > + &vmstate_virtio_start_on_kick,
> > NULL
> > }
> > };