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Re: [Qemu-devel] [PATCH] qmp: handle stop/cont in INMIGRATE state
From: |
Luiz Capitulino |
Subject: |
Re: [Qemu-devel] [PATCH] qmp: handle stop/cont in INMIGRATE state |
Date: |
Fri, 19 Oct 2012 10:23:21 -0300 |
On Fri, 19 Oct 2012 05:27:29 -0400 (EDT)
Paolo Bonzini <address@hidden> wrote:
> > What happens is that a stop command while in INMIGRATE state will just
> > be ignored. Actually, any stops while in a state that pauses vCPUs
> > are ignored.
> >
> > Also, I don't understand what you meant by "racy", care to elaborate?
>
> Case 1: Case 2:
> user runs qemu -incoming -S user runs qemu -incoming -S
> source connects cont command received
> cont command received source connects
>
> In case 1, the VM is resumed at the end of migration, in case 2 it
> is not and an error is reported on QMP. After this patch, it is always
> resumed.
>
> Case 1: Case 2:
> user runs qemu -incoming user runs qemu -incoming
> source connects stop command received
> stop command received source connects
>
> In case 1, the VM runs for a blink of an eye and then stops. In case
> 2 it just starts, with no error reported.
>
> > > In addition, there's nothing that really prevents the user from
> > > typing the block device's passwords before incoming migration is
> > > done, so we may as well allow that.
> >
> > Have you tried it? We seem to support that already.
>
> With HMP yes, with QMP no. You just get "An incoming migration is
> expected before this command can be executed" and no clue that disks
> are encrypted.
We could move the bdrv_iterate() calls before the RUN_STATE_INMIGRATE check
in qmp_cont(), but if this patch fixes all the cases you mention then let's
just apply it.