[libvirt] [PATCH] qemu: Refresh state before starting the VCPUs

[Peter Krempa]

On Mon, Feb 04, 2019 at 13:36:24 +0100, Marc Hartmayer wrote:
> For normal starts (no incoming migration) the refresh of the QEMU
> state must be done before the VCPUs getting started since otherwise
> there might be a race condition between a possible shutdown of the
> guest OS and the QEMU monitor queries.
> 
> This fixes "qemu: migration: Refresh device information after
> transferring state" (93db7eea1b864).
> 
> Signed-off-by: Marc Hartmayer <mhartmay at linux.ibm.com>
> ---
>  src/qemu/qemu_process.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index dace5aaca102..2a3763f40d49 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -6929,10 +6929,17 @@ qemuProcessStart(virConnectPtr conn,
>      }
>      relabel = true;
>  
> -    if (incoming &&
> -        incoming->deferredURI &&
> -        qemuMigrationDstRun(driver, vm, incoming->deferredURI, asyncJob) < 0)
> -        goto stop;
> +    if (incoming) {
> +        if (incoming->deferredURI &&
> +            qemuMigrationDstRun(driver, vm, incoming->deferredURI, asyncJob) < 0)
> +            goto stop;
> +    } else {

This logic does not seem right ...

> +        /* Refresh state of devices from QEMU. During migration this
> +         * needs to happen after the state information is fully
> +         * transferred. */

as this comment clearly states that this should happen after migration.

Here it would happen only when migration is not done.


> +        if (qemuProcessRefreshState(driver, vm, asyncJob) < 0)
> +            goto stop;
> +    }
>  
>      if (qemuProcessFinishStartup(driver, vm, asyncJob,
>                                   !(flags & VIR_QEMU_PROCESS_START_PAUSED),
> @@ -6945,11 +6952,6 @@ qemuProcessStart(virConnectPtr conn,
>          /* Keep watching qemu log for errors during incoming migration, otherwise
>           * unset reporting errors from qemu log. */
>          qemuMonitorSetDomainLog(priv->mon, NULL, NULL, NULL);
> -
> -        /* Refresh state of devices from qemu. During migration this needs to
> -         * happen after the state information is fully transferred. */
> -        if (qemuProcessRefreshState(driver, vm, asyncJob) < 0)
> -            goto stop;
>      }
>  
>      ret = 0;
> -- 
> 2.17.0
> 
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