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Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legac
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest |
Date: |
Thu, 11 Jun 2015 14:13:51 +0200 |
On Thu, Jun 11, 2015 at 02:10:48PM +0200, Thibaut Collet wrote:
> I am not sure to understand your remark:
>
> > It needs to be sent when backend is activated by guest kick
> > (in case of virtio 1, it's possible to use DRIVER_OK for this).
> > This does not happen when VM still runs on source.
>
> Could you confirm rarp can be sent by backend when the
> VHOST_USER_SET_VRING_KICK message is received by the backend ?
No - the time to send pakets is when you start processing
the rings.
And the time to do that is when you detect a kick on
an eventfd, not when said fd is set.
> At this time the migration is completed and there is no risk of confusing the
> switch.
> In this case:
> - there are nothing to do in QEMU to manage legacy guest with
> no GUEST_ANNOUNCE.
> - All the job is done by the backend on the VHOST_USER_SET_VRING_KICK
> reception. Maybe switch notification of live migration is done with a small
> delay but it works
> - This patch can be discarded.
>
>
> On Thu, Jun 11, 2015 at 12:38 PM, Michael S. Tsirkin <address@hidden> wrote:
>
> On Thu, Jun 11, 2015 at 01:54:22PM +0800, Jason Wang wrote:
> >
> >
> > On 06/11/2015 01:49 PM, Thibaut Collet wrote:
> > > > Yes, but still need a mechanism to notify the backend of migration
> > > > completion from qemu side if GUEST_ANNOUNCE is not negotiated.
> > >
> > > backend is aware of a connection with the guest (with the feature
> > > negociation) and can send a rarp. This rarp will be always sent by the
> > > backend when a VM is launched (first start or live migration
> > > completion) if the GUEST_ANOUNCE is not supported.
> > > In this case the issue is solved without done everything by QEMU.
> >
> > The issue is during migration guest network is still active. So sending
> > rarp too early in the destination (e.g during VM is launched) may
> > confuse the switch. We want it to be sent exactly when the migration is
> > completed in destination.
>
> It needs to be sent when backend is activated by guest kick
> (in case of virtio 1, it's possible to use DRIVER_OK for this).
> This does not happen when VM still runs on source.
>
> > > If sending a rarp message on the start of te VM is not accceptable, we
> > > must provide a mechanism similar of the one I have implemented. The
> > > message content can be empty as the backend is able to create the rarp
> > > message.
> >
> > Yes.
>
>
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, (continued)
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Thibaut Collet, 2015/06/10
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Michael S. Tsirkin, 2015/06/10
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Thibaut Collet, 2015/06/10
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Michael S. Tsirkin, 2015/06/10
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Thibaut Collet, 2015/06/11
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Jason Wang, 2015/06/11
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Thibaut Collet, 2015/06/11
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Jason Wang, 2015/06/11
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Michael S. Tsirkin, 2015/06/11
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Thibaut Collet, 2015/06/11
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Thibaut Collet, 2015/06/11
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Jason Wang, 2015/06/12
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Thibaut Collet, 2015/06/12
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Michael S. Tsirkin, 2015/06/12
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Jason Wang, 2015/06/15
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Michael S. Tsirkin, 2015/06/15
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Thibaut Collet, 2015/06/15
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Michael S. Tsirkin, 2015/06/15
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Thibaut Collet, 2015/06/15
- Re: [Qemu-devel] [PATCH v3 2/2] vhost user: Add RARP injection for legacy guest, Jason Wang, 2015/06/16