Add migration capabilities

The management can query the current migration capabilities using
query-migrate-capabilities QMP command.
The user can use 'info migrate_capabilities' HMP command.
Currently only XBZRLE capability is available.

Signed-off-by: Orit Wasserman <owasserm@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

8 files changed, 140 insertions, 0 deletions

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 9bbc7f7555..8b948022ee 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1417,6 +1417,8 @@ show CPU statistics
 show user network stack connection states
 @item info migrate
 show migration status
+@item info migrate_capabilities
+show current migration capabilities
 @item info balloon
 show balloon information
 @item info qtree
diff --git a/hmp.c b/hmp.c
index 25688ab0e2..a17f13b503 100644
--- a/hmp.c
+++ b/hmp.c
@@ -131,8 +131,21 @@ void hmp_info_mice(Monitor *mon)
 void hmp_info_migrate(Monitor *mon)
 {
     MigrationInfo *info;
+    MigrationCapabilityStatusList *caps, *cap;
 
     info = qmp_query_migrate(NULL);
+    caps = qmp_query_migrate_capabilities(NULL);
+
+    /* do not display parameters during setup */
+    if (info->has_status && caps) {
+        monitor_printf(mon, "capabilities: ");
+        for (cap = caps; cap; cap = cap->next) {
+            monitor_printf(mon, "%s: %s ",
+                           MigrationCapability_lookup[cap->value->capability],
+                           cap->value->state ? "on" : "off");
+        }
+        monitor_printf(mon, "\n");
+    }
 
     if (info->has_status) {
         monitor_printf(mon, "Migration status: %s\n", info->status);
@@ -159,6 +172,26 @@ void hmp_info_migrate(Monitor *mon)
     }
 
     qapi_free_MigrationInfo(info);
+    qapi_free_MigrationCapabilityStatusList(caps);
+}
+
+void hmp_info_migrate_capabilities(Monitor *mon)
+{
+    MigrationCapabilityStatusList *caps, *cap;
+
+    caps = qmp_query_migrate_capabilities(NULL);
+
+    if (caps) {
+        monitor_printf(mon, "capabilities: ");
+        for (cap = caps; cap; cap = cap->next) {
+            monitor_printf(mon, "%s: %s ",
+                           MigrationCapability_lookup[cap->value->capability],
+                           cap->value->state ? "on" : "off");
+        }
+        monitor_printf(mon, "\n");
+    }
+
+    qapi_free_MigrationCapabilityStatusList(caps);
 }
 
 void hmp_info_cpus(Monitor *mon)
diff --git a/hmp.h b/hmp.h
index 8d2b0d76da..d111351423 100644
--- a/hmp.h
+++ b/hmp.h
@@ -25,6 +25,7 @@ void hmp_info_uuid(Monitor *mon);
 void hmp_info_chardev(Monitor *mon);
 void hmp_info_mice(Monitor *mon);
 void hmp_info_migrate(Monitor *mon);
+void hmp_info_migrate_capabilities(Monitor *mon);
 void hmp_info_cpus(Monitor *mon);
 void hmp_info_block(Monitor *mon);
 void hmp_info_blockstats(Monitor *mon);
diff --git a/migration.c b/migration.c
index 8db1b433f0..fb620ac0f8 100644
--- a/migration.c
+++ b/migration.c
@@ -113,6 +113,30 @@ uint64_t migrate_max_downtime(void)
     return max_downtime;
 }
 
+MigrationCapabilityStatusList *qmp_query_migrate_capabilities(Error **errp)
+{
+    MigrationCapabilityStatusList *head = NULL;
+    MigrationCapabilityStatusList *caps;
+    MigrationState *s = migrate_get_current();
+    int i;
+
+    for (i = 0; i < MIGRATION_CAPABILITY_MAX; i++) {
+        if (head == NULL) {
+            head = g_malloc0(sizeof(*caps));
+            caps = head;
+        } else {
+            caps->next = g_malloc0(sizeof(*caps));
+            caps = caps->next;
+        }
+        caps->value =
+            g_malloc(sizeof(*caps->value));
+        caps->value->capability = i;
+        caps->value->state = s->enabled_capabilities[i];
+    }
+
+    return head;
+}
+
 MigrationInfo *qmp_query_migrate(Error **errp)
 {
     MigrationInfo *info = g_malloc0(sizeof(*info));
@@ -375,10 +399,16 @@ static MigrationState *migrate_init(const MigrationParams *params)
 {
     MigrationState *s = migrate_get_current();
     int64_t bandwidth_limit = s->bandwidth_limit;
+    bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
+
+    memcpy(enabled_capabilities, s->enabled_capabilities,
+           sizeof(enabled_capabilities));
 
     memset(s, 0, sizeof(*s));
     s->bandwidth_limit = bandwidth_limit;
     s->params = *params;
+    memcpy(s->enabled_capabilities, enabled_capabilities,
+           sizeof(enabled_capabilities));
 
     s->bandwidth_limit = bandwidth_limit;
     s->state = MIG_STATE_SETUP;
diff --git a/migration.h b/migration.h
index 57572a61e9..713aae0253 100644
--- a/migration.h
+++ b/migration.h
@@ -19,6 +19,7 @@
 #include "notify.h"
 #include "error.h"
 #include "vmstate.h"
+#include "qapi-types.h"
 
 struct MigrationParams {
     bool blk;
@@ -39,6 +40,7 @@ struct MigrationState
     void *opaque;
     MigrationParams params;
     int64_t total_time;
+    bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
 };
 
 void process_incoming_migration(QEMUFile *f);
diff --git a/monitor.c b/monitor.c
index 49dccfe854..13b681ab48 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2655,6 +2655,13 @@ static mon_cmd_t info_cmds[] = {
         .mhandler.info = hmp_info_migrate,
     },
     {
+        .name       = "migrate_capabilities",
+        .args_type  = "",
+        .params     = "",
+        .help       = "show current migration capabilities",
+        .mhandler.info = hmp_info_migrate_capabilities,
+    },
+    {
         .name       = "balloon",
         .args_type  = "",
         .params     = "",
diff --git a/qapi-schema.json b/qapi-schema.json
index bd9c450029..f0d4510abe 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -306,6 +306,45 @@
 { 'command': 'query-migrate', 'returns': 'MigrationInfo' }
 
 ##
+# @MigrationCapability
+#
+# Migration capabilities enumeration
+#
+# @xbzrle: Migration supports xbzrle (Xor Based Zero Run Length Encoding).
+#          This feature allows us to minimize migration traffic for certain work
+#          loads, by sending compressed difference of the pages
+#
+# Since: 1.2
+##
+{ 'enum': 'MigrationCapability',
+  'data': ['xbzrle'] }
+
+##
+# @MigrationCapabilityStatus
+#
+# Migration capability information
+#
+# @capability: capability enum
+#
+# @state: capability state bool
+#
+# Since: 1.2
+##
+{ 'type': 'MigrationCapabilityStatus',
+  'data': { 'capability' : 'MigrationCapability', 'state' : 'bool' } }
+
+##
+# @query-migrate-capabilities
+#
+# Returns information about the current migration capabilities status
+#
+# Returns: @MigrationCapabilitiesStatus
+#
+# Since: 1.2
+##
+{ 'command': 'query-migrate-capabilities', 'returns':   ['MigrationCapabilityStatus']}
+
+##
 # @MouseInfo:
 #
 # Information about a mouse device.
diff --git a/qmp-commands.hx b/qmp-commands.hx
index ac466382c0..cb8176686d 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -2143,6 +2143,32 @@ EQMP
     },
 
 SQMP
+query-migrate-capabilities
+-------
+
+Query current migration capabilities
+
+- "capabilities": migration capabilities state
+         - "xbzrle" : XBZRLE state (json-bool)
+
+Arguments:
+
+Example:
+
+-> { "execute": "query-migrate-capabilities" }
+<- { "return": {
+        "capabilities" :  [ { "capability" : "xbzrle", "state" : false } ]
+     }
+   }
+EQMP
+
+    {
+        .name       = "query-migrate-capabilities",
+        .args_type  = "",
+        .mhandler.cmd_new = qmp_marshal_input_query_migrate_capabilities,
+    },
+
+SQMP
 query-balloon
 -------------