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Re: [Qemu-devel] [PATCH 1/4] migration: allow unplug during migration fo
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 1/4] migration: allow unplug during migration for failover devices |
Date: |
Thu, 23 May 2019 16:37:58 +0100 |
User-agent: |
Mutt/1.11.4 (2019-03-13) |
* Jens Freimann (address@hidden) wrote:
> On Tue, May 21, 2019 at 10:33:36AM +0100, Dr. David Alan Gilbert wrote:
> > * Jens Freimann (address@hidden) wrote:
> > > In "b06424de62 migration: Disable hotplug/unplug during migration" we
> > > added a check to disable unplug for all devices until we have figured
> > > out what works. For failover primary devices qdev_unplug() is called
> > > from the migration handler, i.e. during migration.
> > >
> > > This patch adds a flag to DeviceState which is set to false for all
> > > devices and makes an exception for vfio-pci devices that are also
> > > primary devices in a failover pair.
> > >
> > > Signed-off-by: Jens Freimann <address@hidden>
> >
> > So I think this is safe in your case, because you trigger the unplug
> > right at the start of migration during setup and plug after failure;
> > however it's not generally safe - I can't unplug a device while the
> > migration is actually in progress.
>
> I tried to limit it to only allow it in failover case. You're saying
> it's missing something and not strict enough? I could allow it only
> during migration setup. I guess we'll need a similar exception for
> failover in libvirt.
I might be wrong, but I think with your patch I could hot unplug your
device part way through migration; where as I think you only care about
it doing it at a very specific point during setup.
(I still would prefer the hotplug to be done outside qemu, but still
that's separate).
Dave
> regards,
> Jens
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [PATCH 0/4] add failover feature for assigned network devices, Jens Freimann, 2019/05/17
- [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Jens Freimann, 2019/05/17
- Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Dr. David Alan Gilbert, 2019/05/21
- Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Jens Freimann, 2019/05/30
- Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Michael S. Tsirkin, 2019/05/30
- Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Dr. David Alan Gilbert, 2019/05/30
- Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Michael S. Tsirkin, 2019/05/30
- Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Eduardo Habkost, 2019/05/30
- Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Michael S. Tsirkin, 2019/05/30
- Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Eduardo Habkost, 2019/05/31
- Re: [Qemu-devel] [PATCH 3/4] net/virtio: add failover support, Michael S. Tsirkin, 2019/05/31