On 12/19/2017 02:45 AM, Peter Xu wrote:
> After this patch, we will allow QMP clients to enable QMP capabilities
> when sending the first "qmp_capabilities" command. Originally we are
> starting QMP session with no arguments like:
>
> { "execute": "qmp_capabilities" }
>
> Now we can enable some QMP capabilities using (take OOB as example,
> which is the only one capability that we support):
>
> { "execute": "qmp_capabilities",
> "argument": { "enable": [ "oob" ] } }
>
> When the "argument" key is not provided, no capability is enabled.
>
> For capability "oob", the monitor needs to be run on dedicated IO
> thread, otherwise the command will fail. For example, trying to enable
> OOB on a MUXed typed QMP monitor will fail.
>
> One thing to mention is that, QMP capabilities are per-monitor, and also
> when the connection is closed due to some reason, the capabilities will
> be reset.
>
> Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> monitor.c | 65
> +++++++++++++++++++++++++++++++++++++++++++++++++++++---
> qapi-schema.json | 15 ++++++++++---
> 2 files changed, 74 insertions(+), 6 deletions(-)
>
> @@ -1044,6 +1079,20 @@ void qmp_qmp_capabilities(Error **errp)
> return;
> }
>
> + /* Enable QMP capabilities provided by the guest if applicable. */
> + if (has_enable) {
> + qmp_caps_check(cur_mon, enable, &local_err);
> + if (local_err) {
> + /*
> + * Failed check on either of the capabilities will fail
s/either/any/
> + * the apply of all.
s/apply/application/
or even a more verbose
will fail the entire command (and thus not apply any of the other
capabilities that were also requested).
> @@ -3950,6 +3999,10 @@ static QObject *get_qmp_greeting(void)
> qmp_marshal_query_version(NULL, &ver, NULL);
>
> for (cap = 0; cap < QMP_CAPABILITY__MAX; cap++) {
> + if (!mon->use_io_thr && cap == QMP_CAPABILITY_OOB) {
> + /* Monitors that are not using IOThread won't support OOB */
> + continue;
> + }
> qlist_append(cap_list, qstring_from_str(QMPCapability_str(cap)));
I think this hunk belongs in the previous patch - the server should not
advertise 'oob' in the greeting if it will not be able to honor it.
> +++ b/qapi-schema.json
> @@ -102,21 +102,30 @@
> #
> # Enable QMP capabilities.
> #
> -# Arguments: None.
> +# Arguments:
> +#
> +# @enable: List of QMPCapabilities to enable, which is optional.
Maybe document that this list must not include any capabilities that
were not mentioned in the server's initial greeting.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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