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Re: [Qemu-devel] [PATCH] virtio-9p: add savem handlers
From: |
Cornelia Huck |
Subject: |
Re: [Qemu-devel] [PATCH] virtio-9p: add savem handlers |
Date: |
Thu, 12 Nov 2015 15:39:02 +0100 |
On Thu, 12 Nov 2015 15:25:33 +0100
Greg Kurz <address@hidden> wrote:
> On Thu, 12 Nov 2015 13:50:20 +0100
> Cornelia Huck <address@hidden> wrote:
>
> > On Thu, 12 Nov 2015 09:28:21 +0100
> > Greg Kurz <address@hidden> wrote:
> >
> > > On Thu, 22 Oct 2015 19:38:42 +0200
> > > Greg Kurz <address@hidden> wrote:
> > >
> > > > We don't support migration of mounted 9p shares. This is handled by a
> > > > migration blocker.
> > > >
> > > > One would expect, however, to be able to migrate if the share is
> > > > unmounted.
> > > > Unfortunately virtio-9p-device does not register savevm handlers at all
> > > > !
> > > > Migration succeeds and leaves the guest with a dangling device...
> > > >
> > > > This patch simply registers migration handlers for virtio-9p-device.
> > > > Whether
> > > > migration is possible or not still depends on the migration blocker.
> > > >
> > > > Signed-off-by: Greg Kurz <address@hidden>
> > > > ---
> > >
> > > Ping ?
> > >
> > > > Michael, Aneesh,
> > > >
> > > > This is the same patch minus the call to unregister_savevm() since we
> > > > don't
> > > > have an unrealize handler.
> > > >
> > > > I decided to simply drop all the other patches. Hot-unplug support is
> > > > totally
> > > > missing and definitely needs more work. I'll try to come up with a
> > > > solution
> > > > in its own series.
> > > >
> > > > Cheers.
> > > >
> > > > --
> > > > Greg
> > > >
> > > > ---
> > > > hw/9pfs/virtio-9p-device.c | 11 +++++++++++
> > > > 1 file changed, 11 insertions(+)
> > > >
> > > > diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
> > > > index 93a407c45926..e3abcfaffb2a 100644
> > > > --- a/hw/9pfs/virtio-9p-device.c
> > > > +++ b/hw/9pfs/virtio-9p-device.c
> > > > @@ -43,6 +43,16 @@ static void virtio_9p_get_config(VirtIODevice *vdev,
> > > > uint8_t *config)
> > > > g_free(cfg);
> > > > }
> > > >
> > > > +static void virtio_9p_save(QEMUFile *f, void *opaque)
> > > > +{
> > > > + virtio_save(VIRTIO_DEVICE(opaque), f);
> > > > +}
> > > > +
> > > > +static int virtio_9p_load(QEMUFile *f, void *opaque, int version_id)
> > > > +{
> > > > + return virtio_load(VIRTIO_DEVICE(opaque), f, version_id);
> > > > +}
> > > > +
> > > > static void virtio_9p_device_realize(DeviceState *dev, Error **errp)
> > > > {
> > > > VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> > > > @@ -130,6 +140,7 @@ static void virtio_9p_device_realize(DeviceState
> > > > *dev, Error **errp)
> > > > }
> > > > v9fs_path_free(&path);
> > > >
> > > > + register_savevm(dev, "virtio-9p", -1, 1, virtio_9p_save,
> > > > virtio_9p_load, s);
> > > > return;
> > > > out:
> > > > g_free(s->ctx.fs_root);
> >
> > Probably dumb question: Is there no state in the V9fsState, or is it
> > simply irrelevant if there are no mounts?
>
> My understanding is that V9fsState has state but it is not used when
> there are no mounts... maybe worth mentioning in a comment or in the
> changelog ?
If V9fsState will look sensible after migration if there are no mounts,
I think it's worth adding a comment in the code.