[Qemu-devel] [PATCH 6/6] trace: Add QAPI/QMP interfaces to query and control per-vCPU tracing state

["Lluís Vilanova" <vilanova@ac.upc.edu>]

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
---
 monitor.c       |    4 +-
 qapi/trace.json |   20 ++++++--
 qmp-commands.hx |   18 ++++++-
 trace/qmp.c     |  143 ++++++++++++++++++++++++++++++++++++++++++++-----------
 4 files changed, 147 insertions(+), 38 deletions(-)

diff --git a/monitor.c b/monitor.c
index 73eac17..0d090c8 100644
--- a/monitor.c
+++ b/monitor.c
@@ -888,7 +888,7 @@ static void hmp_trace_event(Monitor *mon, const QDict *qdict)
     bool new_state = qdict_get_bool(qdict, "option");
     Error *local_err = NULL;
 
-    qmp_trace_event_set_state(tp_name, new_state, true, true, &local_err);
+    qmp_trace_event_set_state(tp_name, new_state, true, true, false, 0, &local_err);
     if (local_err) {
         error_report_err(local_err);
     }
@@ -1047,7 +1047,7 @@ static void hmp_info_cpustats(Monitor *mon, const QDict *qdict)
 
 static void hmp_info_trace_events(Monitor *mon, const QDict *qdict)
 {
-    TraceEventInfoList *events = qmp_trace_event_get_state("*", NULL);
+    TraceEventInfoList *events = qmp_trace_event_get_state("*", false, 0, NULL);
     TraceEventInfoList *elem;
 
     for (elem = events; elem != NULL; elem = elem->next) {
diff --git a/qapi/trace.json b/qapi/trace.json
index 01b0a52..b9f2e65 100644
--- a/qapi/trace.json
+++ b/qapi/trace.json
@@ -1,6 +1,6 @@
 # -*- mode: python -*-
 #
-# Copyright (C) 2011-2014 Lluís Vilanova <vilanova@ac.upc.edu>
+# Copyright (C) 2011-2016 Lluís Vilanova <vilanova@ac.upc.edu>
 #
 # This work is licensed under the terms of the GNU GPL, version 2 or later.
 # See the COPYING file in the top-level directory.
@@ -29,11 +29,12 @@
 #
 # @name: Event name.
 # @state: Tracing state.
+# @vcpu: Whether this is a per-vCPU event (since 2.6).
 #
 # Since 2.2
 ##
 { 'struct': 'TraceEventInfo',
-  'data': {'name': 'str', 'state': 'TraceEventState'} }
+  'data': {'name': 'str', 'state': 'TraceEventState', 'vcpu': 'bool'} }
 
 ##
 # @trace-event-get-state:
@@ -41,13 +42,18 @@
 # Query the state of events.
 #
 # @name: Event name pattern (case-sensitive glob).
+# @vcpu: #optional The vCPU to check (any by default; since 2.6).
 #
 # Returns: a list of @TraceEventInfo for the matching events
 #
+# For any event without the "vcpu" property:
+# - If @name is a pattern and @vcpu is set, events are ignored.
+# - If @name is not a pattern and @vcpu is set, an error is raised.
+#
 # Since 2.2
 ##
 { 'command': 'trace-event-get-state',
-  'data': {'name': 'str'},
+  'data': {'name': 'str', '*vcpu': 'int'},
   'returns': ['TraceEventInfo'] }
 
 ##
@@ -58,8 +64,14 @@
 # @name: Event name pattern (case-sensitive glob).
 # @enable: Whether to enable tracing.
 # @ignore-unavailable: #optional Do not match unavailable events with @name.
+# @vcpu: #optional The vCPU to act upon (all by default; since 2.6).
+#
+# For any event without the "vcpu" property:
+# - If @name is a pattern and @vcpu is set, events are ignored.
+# - If @name is not a pattern and @vcpu is set, an error is raised.
 #
 # Since 2.2
 ##
 { 'command': 'trace-event-set-state',
-  'data': {'name': 'str', 'enable': 'bool', '*ignore-unavailable': 'bool'} }
+  'data': {'name': 'str', 'enable': 'bool', '*ignore-unavailable': 'bool',
+           '*vcpu': 'int'} }
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 085dc7d..1e4f9a7 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -4596,7 +4596,7 @@ EQMP
 
     {
         .name       = "trace-event-get-state",
-        .args_type  = "name:s",
+        .args_type  = "name:s,vcpu:i?",
         .mhandler.cmd_new = qmp_marshal_trace_event_get_state,
     },
 
@@ -4606,6 +4606,11 @@ trace-event-get-state
 
 Query the state of events.
 
+Arguments:
+
+- "name": Event name pattern (json-string).
+- "vcpu": Specific vCPU to query, any vCPU by default (json-int, optional).
+
 Example:
 
 -> { "execute": "trace-event-get-state", "arguments": { "name": "qemu_memalign" } }
@@ -4614,7 +4619,7 @@ EQMP
 
     {
         .name       = "trace-event-set-state",
-        .args_type  = "name:s,enable:b,ignore-unavailable:b?",
+        .args_type  = "name:s,enable:b,ignore-unavailable:b?,vcpu:i?",
         .mhandler.cmd_new = qmp_marshal_trace_event_set_state,
     },
 
@@ -4624,6 +4629,14 @@ trace-event-set-state
 
 Set the state of events.
 
+Arguments:
+
+- "name": Event name pattern (json-string).
+- "enable": Whether to enable or disable the event (json-bool).
+- "ignore-unavailable": Whether to ignore errors for events that cannot be
+  changed (json-bool, optional).
+- "vcpu": Specific vCPU to set, all vCPUs by default (json-int, optional).
+
 Example:
 
 -> { "execute": "trace-event-set-state", "arguments": { "name": "qemu_memalign", "enable": "true" } }
@@ -4692,7 +4705,6 @@ Move mouse pointer to absolute coordinates (20000, 400).
                { "type": "abs", "data" : { "axis": "X", "value" : 20000 } },
                { "type": "abs", "data" : { "axis": "Y", "value" : 400 } } ] } }
 <- { "return": {} }
-
 EQMP
 
     {
diff --git a/trace/qmp.c b/trace/qmp.c
index 6320b4b..876e789 100644
--- a/trace/qmp.c
+++ b/trace/qmp.c
@@ -1,7 +1,7 @@
 /*
  * QMP commands for tracing events.
  *
- * Copyright (C) 2014 Lluís Vilanova <vilanova@ac.upc.edu>
+ * Copyright (C) 2014-2016 Lluís Vilanova <vilanova@ac.upc.edu>
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
@@ -13,63 +13,148 @@
 #include "trace/control.h"
 
 
-TraceEventInfoList *qmp_trace_event_get_state(const char *name, Error **errp)
+static bool get_cpu(bool has_vcpu, int vcpu, CPUState **cpu, Error **errp)
+{
+    if (has_vcpu) {
+        *cpu = qemu_get_cpu(vcpu);
+        if (*cpu == NULL) {
+            error_setg(errp, "invalid vCPU index %u", vcpu);
+            return false;
+        }
+    } else {
+        *cpu = NULL;
+    }
+    return true;
+}
+
+static bool check_events(bool has_vcpu, bool ignore_unavailable, bool is_pattern,
+                         const char *name, Error **errp)
+{
+    if (!is_pattern) {
+        TraceEvent *ev = trace_event_name(name);
+
+        /* error for non-existing event */
+        if (ev == NULL) {
+            error_setg(errp, "unknown event \"%s\"", name);
+            return false;
+        }
+
+        /* error for non-vcpu event */
+        if (has_vcpu && trace_event_get_cpu_id(ev) == trace_event_cpu_count()) {
+            error_setg(errp, "event \"%s\" is not vCPU-specific", name);
+            return false;
+        }
+
+        /* error for unavailable event */
+        if (!ignore_unavailable && !trace_event_get_state_static(ev)) {
+            error_setg(errp, "event \"%s\" is disabled", name);
+            return false;
+        }
+
+        return true;
+    } else {
+        /* error for unavailable events */
+        TraceEvent *ev = NULL;
+        while ((ev = trace_event_pattern(name, ev)) != NULL) {
+            if (!ignore_unavailable && !trace_event_get_state_static(ev)) {
+                error_setg(errp, "event \"%s\" is disabled", trace_event_get_name(ev));
+                return false;
+            }
+        }
+        return true;
+    }
+}
+
+TraceEventInfoList *qmp_trace_event_get_state(const char *name,
+                                              bool has_vcpu, int64_t vcpu,
+                                              Error **errp)
 {
     TraceEventInfoList *events = NULL;
-    bool found = false;
     TraceEvent *ev;
+    bool is_pattern = trace_event_is_pattern(name);
+    CPUState *cpu;
 
+    /* Check provided vcpu */
+    if (!get_cpu(has_vcpu, vcpu, &cpu, errp)) {
+        return NULL;
+    }
+
+    /* Check events */
+    if (!check_events(has_vcpu, true, is_pattern, name, errp)) {
+        return NULL;
+    }
+
+    /* Get states (all errors checked above) */
     ev = NULL;
     while ((ev = trace_event_pattern(name, ev)) != NULL) {
-        TraceEventInfoList *elem = g_new(TraceEventInfoList, 1);
+        TraceEventInfoList *elem;
+        bool is_vcpu = trace_event_get_cpu_id(ev) != trace_event_cpu_count();
+        if (has_vcpu && !is_vcpu) {
+            continue;
+        }
+
+        elem = g_new(TraceEventInfoList, 1);
         elem->value = g_new(TraceEventInfo, 1);
+        elem->value->vcpu = is_vcpu;
         elem->value->name = g_strdup(trace_event_get_name(ev));
+
         if (!trace_event_get_state_static(ev)) {
             elem->value->state = TRACE_EVENT_STATE_UNAVAILABLE;
-        } else if (!trace_event_get_state_dynamic(ev)) {
-            elem->value->state = TRACE_EVENT_STATE_DISABLED;
         } else {
-            elem->value->state = TRACE_EVENT_STATE_ENABLED;
+            if (has_vcpu) {
+                if (is_vcpu) {
+                    if (trace_event_get_cpu_state_dynamic(cpu, ev)) {
+                        elem->value->state = TRACE_EVENT_STATE_ENABLED;
+                    } else {
+                        elem->value->state = TRACE_EVENT_STATE_DISABLED;
+                    }
+                }
+                /* else: already skipped above */
+            } else {
+                if (trace_event_get_state_dynamic(ev)) {
+                    elem->value->state = TRACE_EVENT_STATE_ENABLED;
+                } else {
+                    elem->value->state = TRACE_EVENT_STATE_DISABLED;
+                }
+            }
         }
         elem->next = events;
         events = elem;
-        found = true;
-    }
-
-    if (!found && !trace_event_is_pattern(name)) {
-        error_setg(errp, "unknown event \"%s\"", name);
     }
 
     return events;
 }
 
 void qmp_trace_event_set_state(const char *name, bool enable,
-                               bool has_ignore_unavailable,
-                               bool ignore_unavailable, Error **errp)
+                               bool has_ignore_unavailable, bool ignore_unavailable,
+                               bool has_vcpu, int64_t vcpu,
+                               Error **errp)
 {
-    bool found = false;
     TraceEvent *ev;
+    bool is_pattern = trace_event_is_pattern(name);
+    CPUState *cpu;
 
-    /* Check all selected events are dynamic */
-    ev = NULL;
-    while ((ev = trace_event_pattern(name, ev)) != NULL) {
-        found = true;
-        if (!(has_ignore_unavailable && ignore_unavailable) &&
-            !trace_event_get_state_static(ev)) {
-            error_setg(errp, "cannot set dynamic tracing state for \"%s\"",
-                       trace_event_get_name(ev));
-            return;
-        }
+    /* Check provided vcpu */
+    if (!get_cpu(has_vcpu, vcpu, &cpu, errp)) {
+        return;
     }
-    if (!found && !trace_event_is_pattern(name)) {
-        error_setg(errp, "unknown event \"%s\"", name);
+
+    /* Check events */
+    if (!check_events(has_vcpu, has_ignore_unavailable && ignore_unavailable,
+                      is_pattern, name, errp)) {
         return;
     }
 
-    /* Apply changes */
+    /* Apply changes (all errors checked above) */
     ev = NULL;
     while ((ev = trace_event_pattern(name, ev)) != NULL) {
-        if (trace_event_get_state_static(ev)) {
+        if (!trace_event_get_state_static(ev) ||
+            (has_vcpu && trace_event_get_cpu_id(ev) == trace_event_cpu_count())) {
+            continue;
+        }
+        if (has_vcpu) {
+            trace_event_set_cpu_state_dynamic(cpu, ev, enable);
+        } else {
             trace_event_set_state_dynamic(ev, enable);
         }
     }