docs: reSTify virtio-balloon-stats documentation and move to docs/interop

The virtio-balloon-stats documentation might be useful for people that
are implementing software that talks to QEMU via QMP, so this should
reside in the docs/interop/ directory. While we're at it, also convert
the file to restructured text and mention it in the MAINTAINERS file.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220105115245.420945-1-thuth@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

MAINTAINERS

@@ -1932,6 +1932,7 @@ virtio-balloon
 M: Michael S. Tsirkin <mst@redhat.com>
 M: David Hildenbrand <david@redhat.com>
 S: Maintained
+F: docs/interop/virtio-balloon-stats.rst
 F: hw/virtio/virtio-balloon*.c
 F: include/hw/virtio/virtio-balloon.h
 F: softmmu/balloon.c

docs/interop/index.rst

@@ -22,3 +22,4 @@ are useful for making QEMU interoperate with other software.
    vhost-user
    vhost-user-gpu
    vhost-vdpa
+   virtio-balloon-stats

docs/interop/virtio-balloon-stats.rst

@@ -1,4 +1,4 @@
-virtio balloon memory statistics
+Virtio balloon memory statistics
 ================================
 
 The virtio balloon driver supports guest memory statistics reporting. These
@@ -9,10 +9,12 @@ Before querying the available stats, clients first have to enable polling.
 This is done by writing a time interval value (in seconds) to the
 guest-stats-polling-interval property. This value can be:
 
-  > 0  enables polling in the specified interval. If polling is already
+  > 0
+       enables polling in the specified interval. If polling is already
        enabled, the polling time interval is changed to the new value
 
-  0    disables polling. Previous polled statistics are still valid and
+  0
+       disables polling. Previous polled statistics are still valid and
        can be queried.
 
 Once polling is enabled, the virtio-balloon device in QEMU will start
@@ -22,7 +24,7 @@ interval.
 To retrieve those stats, clients have to query the guest-stats property,
 which will return a dictionary containing:
 
-  o A key named 'stats', containing all available stats. If the guest
+  * A key named 'stats', containing all available stats. If the guest
     doesn't support a particular stat, or if it couldn't be retrieved,
     its value will be -1. Currently, the following stats are supported:
 
@@ -37,7 +39,7 @@ which will return a dictionary containing:
       - stat-htlb-pgalloc
       - stat-htlb-pgfail
 
-  o A key named last-update, which contains the last stats update
+  * A key named last-update, which contains the last stats update
     timestamp in seconds. Since this timestamp is generated by the host,
     a buggy guest can't influence its value. The value is 0 if the guest
     has not updated the stats (yet).
@@ -61,32 +63,32 @@ It's also important to note the following:
    respond to the request the timer will never be re-armed, which has
    the same effect as disabling polling
 
-Here are a few examples. QEMU is started with '-device virtio-balloon',
+Here are a few examples. QEMU is started with ``-device virtio-balloon``,
-which generates '/machine/peripheral-anon/device[1]' as the QOM path for
+which generates ``/machine/peripheral-anon/device[1]`` as the QOM path for
 the balloon device.
 
-Enable polling with 2 seconds interval:
+Enable polling with 2 seconds interval::
 
-{ "execute": "qom-set",
+  { "execute": "qom-set",
                "arguments": { "path": "/machine/peripheral-anon/device[1]",
                "property": "guest-stats-polling-interval", "value": 2 } }
 
-{ "return": {} }
+  { "return": {} }
 
-Change polling to 10 seconds:
+Change polling to 10 seconds::
 
-{ "execute": "qom-set",
+  { "execute": "qom-set",
                "arguments": { "path": "/machine/peripheral-anon/device[1]",
                "property": "guest-stats-polling-interval", "value": 10 } }
 
-{ "return": {} }
+  { "return": {} }
 
-Get stats:
+Get stats::
 
-{ "execute": "qom-get",
+  { "execute": "qom-get",
                "arguments": { "path": "/machine/peripheral-anon/device[1]",
                "property": "guest-stats" } }
-{
+  {
     "return": {
         "stats": {
             "stat-swap-out": 0,
@@ -98,12 +100,12 @@ Get stats:
         },
         "last-update": 1358529861
     }
-}
+  }
 
-Disable polling:
+Disable polling::
 
-{ "execute": "qom-set",
+  { "execute": "qom-set",
                "arguments": { "path": "/machine/peripheral-anon/device[1]",
                "property": "stats-polling-interval", "value": 0 } }
 
-{ "return": {} }
+  { "return": {} }