qmp: add filtering of statistics by provider

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.

If a provider is specified more than once in the filter, each request
will be included separately in the output.

Extracted from a patch by Mark Kanda.

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 547de842fd..2e819beaeb 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;