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Re: [Qemu-devel] [PATCH v3 0/5] virtio-9p: hotplug and migration support
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v3 0/5] virtio-9p: hotplug and migration support |
Date: |
Tue, 20 Oct 2015 22:39:41 +0300 |
On Tue, Oct 20, 2015 at 08:00:53PM +0200, Greg Kurz wrote:
> On Tue, 20 Oct 2015 15:53:08 +0300
> "Michael S. Tsirkin" <address@hidden> wrote:
>
> > On Tue, Oct 20, 2015 at 11:16:40AM +0200, Greg Kurz wrote:
> > > We already have a blocker to prevent migration of an active virtio-9p
> > > device.
> > > But in fact, there is no migration support at all for 9p, even if the
> > > device
> > > is considered to be quiescent (when the VirtFS share is not mounted):
> > > migration
> > > succeeds but the device is lost in the restarted guest.
> > > Hotunplug of a virtio-9p device is not supported either (no unrealize
> > > handler)
> > > and leads to a QEMU crash on the source node, if one unplugs and migrates.
> > >
> > > This series tries to fix that and brings hotplug and migration support of
> > > *quiescent* virtio-9p devices.
> > >
> > > v2->v3:
> > > - renamed QDEV handler @unpluggable to @unplug_is_blocked (patches 2/5
> > > and 3/5)
> > >
> > > v1->v2:
> > > - introduced unplug blocker (patches 2/5 and 3/5)
> > > - moved fixes to separate patches (see individual changelogs)
> >
> > I have some doubts about how hotunplug is handled, but migration
> > looks ok.
> > Is there a dependency, or can I just pick savevm things meanwhile?
> >
>
> Well... you can drop the unplug blocker patches (2/5 and 3/5) but the
> savevm patch (5/5) modifies a function introduced by the unrealize
> patch (4/5):
>
> @@ -146,6 +157,7 @@ static void virtio_9p_device_unrealize(DeviceState *dev,
> Error **errp)
> v9fs_release_worker_threads();
> g_free(s->ctx.fs_root);
> g_free(s->tag);
> + unregister_savevm(dev, "virtio-9p", s);
> virtio_cleanup(vdev);
> }
>
> and not having an unrealize handler calling unregister_savevm() means
> unplug will succeed and leave a dangling pointer in the vm_change_state
> list... This causes a systematic crash of the source QEMU when attempting
> a migration.
OK ... could you pls re-arrange it so that savevm can be applied first?
> > > ---
> > >
> > > Greg Kurz (5):
> > > virtio-9p-coth: fix init function
> > > qdev: add the @unplug_is_blocked handler
> > > virtio-9p: block hot-unplug when device is active
> > > virtio-9p: add unrealize handler
> > > virtio-9p: add savem handlers
> > >
> > >
> > > hw/9pfs/virtio-9p-coth.c | 22 ++++++++++++++++++----
> > > hw/9pfs/virtio-9p-coth.h | 2 ++
> > > hw/9pfs/virtio-9p-device.c | 24 ++++++++++++++++++++++++
> > > hw/9pfs/virtio-9p.c | 14 ++++++++++++++
> > > hw/9pfs/virtio-9p.h | 2 ++
> > > hw/core/qdev.c | 4 ++++
> > > hw/s390x/virtio-ccw.c | 8 ++++++++
> > > hw/virtio/virtio-pci.c | 8 ++++++++
> > > include/hw/qdev-core.h | 4 ++++
> > > 9 files changed, 84 insertions(+), 4 deletions(-)
> >
- [Qemu-devel] [PATCH v3 0/5] virtio-9p: hotplug and migration support, Greg Kurz, 2015/10/20
- [Qemu-devel] [PATCH v3 2/5] qdev: add the @unplug_is_blocked handler, Greg Kurz, 2015/10/20
- [Qemu-devel] [PATCH v3 1/5] virtio-9p-coth: fix init function, Greg Kurz, 2015/10/20
- [Qemu-devel] [PATCH v3 3/5] virtio-9p: block hot-unplug when device is active, Greg Kurz, 2015/10/20
- [Qemu-devel] [PATCH v3 4/5] virtio-9p: add unrealize handler, Greg Kurz, 2015/10/20
- [Qemu-devel] [PATCH v3 5/5] virtio-9p: add savem handlers, Greg Kurz, 2015/10/20
- Re: [Qemu-devel] [PATCH v3 0/5] virtio-9p: hotplug and migration support, Michael S. Tsirkin, 2015/10/20