[PATCH 5/8] qmp: add filtering of statistics by provider

[Paolo Bonzini]

Allow retrieving the statistics from a specific provider only.
This can be used in the future by HMP commands such as "info
sync-profile" or "info profile".  The next patch also adds
filter-by-provider capabilities to the HMP equivalent of
query-stats, "info stats".

Example:

{ "execute": "query-stats",
  "arguments": {
    "target": "vm",
    "providers": [
      { "provider": "kvm" } ] } }

The QAPI is a bit more verbose than just a list of StatsProvider,
so that it can be subsequently extended with filtering of statistics
by name.

Extracted from a patch by Mark Kanda.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 accel/kvm/kvm-all.c     |  3 ++-
 include/monitor/stats.h |  4 +++-
 monitor/hmp-cmds.c      |  2 +-
 monitor/qmp-cmds.c      | 45 ++++++++++++++++++++++++++++++++---------
 qapi/stats.json         | 17 ++++++++++++++--
 5 files changed, 56 insertions(+), 15 deletions(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 3ee431a431..461b6cf927 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2644,7 +2644,8 @@ static int kvm_init(MachineState *ms)
     }
 
     if (kvm_check_extension(kvm_state, KVM_CAP_BINARY_STATS_FD)) {
-        add_stats_callbacks(query_stats_cb, query_stats_schemas_cb);
+        add_stats_callbacks(STATS_PROVIDER_KVM, query_stats_cb,
+                            query_stats_schemas_cb);
     }
 
     return 0;
diff --git a/include/monitor/stats.h b/include/monitor/stats.h
index 8c50feeaa9..840c4ed08e 100644
--- a/include/monitor/stats.h
+++ b/include/monitor/stats.h
@@ -17,10 +17,12 @@ typedef void SchemaRetrieveFunc(StatsSchemaList **result, 
Error **errp);
 /*
  * Register callbacks for the QMP query-stats command.
  *
+ * @provider: stats provider
  * @stats_fn: routine to query stats:
  * @schema_fn: routine to query stat schemas:
  */
-void add_stats_callbacks(StatRetrieveFunc *stats_fn,
+void add_stats_callbacks(StatsProvider provider,
+                         StatRetrieveFunc *stats_fn,
                          SchemaRetrieveFunc *schemas_fn);
 
 /*
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index c0cb440902..8d2c4792d5 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -2394,7 +2394,7 @@ void hmp_info_stats(Monitor *mon, const QDict *qdict)
         goto exit_no_print;
     }
 
-    schema = qmp_query_stats_schemas(&err);
+    schema = qmp_query_stats_schemas(false, 0, &err);
     if (err) {
         goto exit;
     }
diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
index ebf6f49446..7be0e7414a 100644
--- a/monitor/qmp-cmds.c
+++ b/monitor/qmp-cmds.c
@@ -445,6 +445,7 @@ HumanReadableText *qmp_x_query_irq(Error **errp)
 }
 
 typedef struct StatsCallbacks {
+    StatsProvider provider;
     StatRetrieveFunc *stats_cb;
     SchemaRetrieveFunc *schemas_cb;
     QTAILQ_ENTRY(StatsCallbacks) next;
@@ -453,16 +454,34 @@ typedef struct StatsCallbacks {
 static QTAILQ_HEAD(, StatsCallbacks) stats_callbacks =
     QTAILQ_HEAD_INITIALIZER(stats_callbacks);
 
-void add_stats_callbacks(StatRetrieveFunc *stats_fn,
+void add_stats_callbacks(StatsProvider provider,
+                         StatRetrieveFunc *stats_fn,
                          SchemaRetrieveFunc *schemas_fn)
 {
     StatsCallbacks *entry = g_new(StatsCallbacks, 1);
+    entry->provider = provider;
     entry->stats_cb = stats_fn;
     entry->schemas_cb = schemas_fn;
 
     QTAILQ_INSERT_TAIL(&stats_callbacks, entry, next);
 }
 
+static bool stats_provider_requested(StatsProvider provider,
+                                     StatsFilter *filter)
+{
+    StatsRequestList *request;
+
+    if (!filter->has_providers) {
+        return true;
+    }
+    for (request = filter->providers; request; request = request->next) {
+        if (request->value->provider == provider) {
+            return true;
+        }
+    }
+    return false;
+}
+
 StatsResultList *qmp_query_stats(StatsFilter *filter, Error **errp)
 {
     StatsResultList *stats_results = NULL;
@@ -487,27 +506,33 @@ StatsResultList *qmp_query_stats(StatsFilter *filter, 
Error **errp)
     }
 
     QTAILQ_FOREACH(entry, &stats_callbacks, next) {
-        entry->stats_cb(&stats_results, filter->target, targets, errp);
-        if (*errp) {
-            qapi_free_StatsResultList(stats_results);
-            return NULL;
+        if (stats_provider_requested(entry->provider, filter)) {
+            entry->stats_cb(&stats_results, filter->target, targets, errp);
+            if (*errp) {
+                qapi_free_StatsResultList(stats_results);
+                return NULL;
+            }
         }
     }
 
     return stats_results;
 }
 
-StatsSchemaList *qmp_query_stats_schemas(Error **errp)
+StatsSchemaList *qmp_query_stats_schemas(bool has_provider,
+                                         StatsProvider provider,
+                                         Error **errp)
 {
     StatsSchemaList *stats_results = NULL;
     StatsCallbacks *entry;
     ERRP_GUARD();
 
     QTAILQ_FOREACH(entry, &stats_callbacks, next) {
-        entry->schemas_cb(&stats_results, errp);
-        if (*errp) {
-            qapi_free_StatsSchemaList(stats_results);
-            return NULL;
+        if (!has_provider || provider == entry->provider) {
+            entry->schemas_cb(&stats_results, errp);
+            if (*errp) {
+                qapi_free_StatsSchemaList(stats_results);
+                return NULL;
+            }
         }
     }
 
diff --git a/qapi/stats.json b/qapi/stats.json
index e8ed907793..b75bb86124 100644
--- a/qapi/stats.json
+++ b/qapi/stats.json
@@ -68,6 +68,18 @@
 { 'enum': 'StatsTarget',
   'data': [ 'vm', 'vcpu' ] }
 
+##
+# @StatsRequest:
+#
+# Indicates a set of statistics that should be returned by query-stats.
+#
+# @provider: provider for which to return statistics.
+#
+# Since: 7.1
+##
+{ 'struct': 'StatsRequest',
+  'data': { 'provider': 'StatsProvider' } }
+
 ##
 # @StatsVCPUFilter:
 #
@@ -85,11 +97,12 @@
 # request statistics and optionally the required subset of information for
 # that target:
 # - which vCPUs to request statistics for
+# - which provider to request statistics from
 #
 # Since: 7.1
 ##
 { 'union': 'StatsFilter',
-        'base': { 'target': 'StatsTarget' },
+        'base': { 'target': 'StatsTarget', '*providers': [ 'StatsRequest' ] },
   'discriminator': 'target',
   'data': { 'vcpu': 'StatsVCPUFilter' } }
 
@@ -225,5 +238,5 @@
 # Since: 7.1
 ##
 { 'command': 'query-stats-schemas',
-  'data': { },
+  'data': { '*provider': 'StatsProvider' },
   'returns': [ 'StatsSchema' ] }
-- 
2.36.0