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[Qemu-devel] [RFC v3 13/27] qmp: negociate QMP capabilities
From: |
Peter Xu |
Subject: |
[Qemu-devel] [RFC v3 13/27] qmp: negociate QMP capabilities |
Date: |
Mon, 6 Nov 2017 17:46:29 +0800 |
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.
Signed-off-by: Peter Xu <address@hidden>
---
monitor.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
qapi-schema.json | 15 ++++++++++++---
2 files changed, 68 insertions(+), 4 deletions(-)
diff --git a/monitor.c b/monitor.c
index dd192b6b91..dba56fbcdf 100644
--- a/monitor.c
+++ b/monitor.c
@@ -167,6 +167,7 @@ typedef struct {
* mode.
*/
QmpCommandList *commands;
+ bool qmp_caps[QMP_CAPABILITY__MAX];
} MonitorQMP;
/*
@@ -1037,8 +1038,42 @@ static void monitor_init_qmp_commands(void)
qmp_marshal_qmp_capabilities, QCO_NO_OPTIONS);
}
-void qmp_qmp_capabilities(Error **errp)
+static void qmp_caps_check(Monitor *mon, QMPCapabilityList *list,
+ Error **errp)
+{
+ for (; list; list = list->next) {
+ assert(list->value < QMP_CAPABILITY__MAX);
+ switch (list->value) {
+ case QMP_CAPABILITY_OOB:
+ if (!mon->use_io_thr) {
+ /*
+ * Out-Of-Band only works with monitors that are
+ * running on dedicated IOThread.
+ */
+ error_setg(errp, "This monitor does not support "
+ "Out-Of-Band (OOB)");
+ return;
+ }
+ break;
+ default:
+ break;
+ }
+ }
+}
+
+/* This function should only be called after capabilities are checked. */
+static void qmp_caps_apply(Monitor *mon, QMPCapabilityList *list)
+{
+ for (; list; list = list->next) {
+ mon->qmp.qmp_caps[list->value] = true;
+ }
+}
+
+void qmp_qmp_capabilities(bool has_enable, QMPCapabilityList *enable,
+ Error **errp)
{
+ Error *local_err = NULL;
+
if (cur_mon->qmp.commands == &qmp_commands) {
error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
"Capabilities negotiation is already complete, command "
@@ -1046,6 +1081,20 @@ 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
+ * the apply of all.
+ */
+ error_propagate(errp, local_err);
+ return;
+ }
+ qmp_caps_apply(cur_mon, enable);
+ }
+
cur_mon->qmp.commands = &qmp_commands;
}
@@ -3963,6 +4012,11 @@ static QObject *get_qmp_greeting(void)
return QOBJECT(result);
}
+static void monitor_qmp_caps_reset(Monitor *mon)
+{
+ memset(mon->qmp.qmp_caps, 0, sizeof(mon->qmp.qmp_caps));
+}
+
static void monitor_qmp_event(void *opaque, int event)
{
QObject *data;
@@ -3971,6 +4025,7 @@ static void monitor_qmp_event(void *opaque, int event)
switch (event) {
case CHR_EVENT_OPENED:
mon->qmp.commands = &qmp_cap_negotiation_commands;
+ monitor_qmp_caps_reset(mon);
data = get_qmp_greeting();
monitor_json_emitter(mon, data);
qobject_decref(data);
diff --git a/qapi-schema.json b/qapi-schema.json
index 03201578b4..531fd4c0db 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -102,21 +102,30 @@
#
# Enable QMP capabilities.
#
-# Arguments: None.
+# Arguments:
+#
+# @enable: List of QMPCapabilities to enable, which is optional.
+# If not provided, it means no QMP capabilities will be
+# enabled. (since 2.12)
#
# Example:
#
-# -> { "execute": "qmp_capabilities" }
+# -> { "execute": "qmp_capabilities",
+# "arguments": { "enable": [ "oob" ] } }
# <- { "return": {} }
#
# Notes: This command is valid exactly when first connecting: it must be
# issued before any other command will be accepted, and will fail once the
# monitor is accepting other commands. (see qemu docs/interop/qmp-spec.txt)
#
+# QMP client needs to explicitly enable QMP capabilities, otherwise
+# all the QMP capabilities will be turned off by default.
+#
# Since: 0.13
#
##
-{ 'command': 'qmp_capabilities' }
+{ 'command': 'qmp_capabilities',
+ 'data': { '*enable': [ 'QMPCapability' ] } }
##
# @QMPCapability:
--
2.13.5
- [Qemu-devel] [RFC v3 09/27] monitor: let mon_list be tail queue, (continued)
[Qemu-devel] [RFC v3 11/27] monitor: allow to use IO thread for parsing, Peter Xu, 2017/11/06
[Qemu-devel] [RFC v3 12/27] qmp: introduce QMPCapability, Peter Xu, 2017/11/06
[Qemu-devel] [RFC v3 13/27] qmp: negociate QMP capabilities,
Peter Xu <=
[Qemu-devel] [RFC v3 14/27] qmp: introduce some capability helpers, Peter Xu, 2017/11/06
[Qemu-devel] [RFC v3 15/27] monitor: introduce monitor_qmp_respond(), Peter Xu, 2017/11/06
[Qemu-devel] [RFC v3 16/27] monitor: let monitor_{suspend|resume} thread safe, Peter Xu, 2017/11/06
[Qemu-devel] [RFC v3 17/27] monitor: separate QMP parser and dispatcher, Peter Xu, 2017/11/06
[Qemu-devel] [RFC v3 18/27] qmp: add new event "request-dropped", Peter Xu, 2017/11/06