qemu: use query-cpus-fast in JSON monitor

Use query-cpus-fast instead of query-cpus if supported by QEMU.
Based on the QEMU_CAPS_QUERY_CPUS_FAST capability.

Signed-off-by: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>

src/qemu/qemu_domain.c

@@ -9035,15 +9035,19 @@ qemuDomainRefreshVcpuInfo(virQEMUDriverPtr driver,
     size_t maxvcpus = virDomainDefGetVcpusMax(vm->def);
     size_t i;
     bool hotplug;
+    bool fast;
     int rc;
     int ret = -1;
 
     hotplug = qemuDomainSupportsNewVcpuHotplug(vm);
+    fast = virQEMUCapsGet(QEMU_DOMAIN_PRIVATE(vm)->qemuCaps,
+                          QEMU_CAPS_QUERY_CPUS_FAST);
 
     if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
         return -1;
 
-    rc = qemuMonitorGetCPUInfo(qemuDomainGetMonitor(vm), &info, maxvcpus, hotplug);
+    rc = qemuMonitorGetCPUInfo(qemuDomainGetMonitor(vm), &info, maxvcpus,
+                               hotplug, fast);
 
     if (qemuDomainObjExitMonitor(driver, vm) < 0)
         goto cleanup;
@@ -9062,7 +9066,7 @@ qemuDomainRefreshVcpuInfo(virQEMUDriverPtr driver,
          * thread, but it runs every vCPU in that same thread. So it
          * is impossible to setup different affinity per thread.
          *
-         * What's more the 'query-cpus' command returns bizarre
+         * What's more the 'query-cpus[-fast]' command returns bizarre
          * data for the threads. It gives the TCG thread for the
          * vCPU 0, but for vCPUs 1-> N, it actually replies with
          * the main process thread ID.
@@ -9150,6 +9154,7 @@ qemuDomainRefreshVcpuHalted(virQEMUDriverPtr driver,
     virBitmapPtr haltedmap = NULL;
     size_t i;
     int ret = -1;
+    bool fast;
 
     /* Not supported currently for TCG, see qemuDomainRefreshVcpuInfo */
     if (vm->def->virtType == VIR_DOMAIN_VIRT_QEMU)
@@ -9163,8 +9168,10 @@ qemuDomainRefreshVcpuHalted(virQEMUDriverPtr driver,
     if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
         return -1;
 
-    haltedmap = qemuMonitorGetCpuHalted(qemuDomainGetMonitor(vm), maxvcpus);
+    fast = virQEMUCapsGet(QEMU_DOMAIN_PRIVATE(vm)->qemuCaps,
-
+                          QEMU_CAPS_QUERY_CPUS_FAST);
+    haltedmap = qemuMonitorGetCpuHalted(qemuDomainGetMonitor(vm), maxvcpus,
+                                        fast);
     if (qemuDomainObjExitMonitor(driver, vm) < 0 || !haltedmap)
         goto cleanup;
 

src/qemu/qemu_monitor.c

@@ -1847,15 +1847,16 @@ qemuMonitorGetCPUInfoLegacy(struct qemuMonitorQueryCpusEntry *cpuentries,
  *
  * This function stitches together data retrieved via query-hotpluggable-cpus
  * which returns entities on the hotpluggable level (which may describe more
- * than one guest logical vcpu) with the output of query-cpus, having an entry
+ * than one guest logical vcpu) with the output of query-cpus (or
- * per enabled guest logical vcpu.
+ * query-cpus-fast), having an entry per enabled guest logical vcpu.
  *
  * query-hotpluggable-cpus conveys following information:
  * - topology information and number of logical vcpus this entry creates
  * - device type name of the entry that needs to be used when hotplugging
- * - qom path in qemu which can be used to map the entry against query-cpus
+ * - qom path in qemu which can be used to map the entry against
+ *   query-cpus[-fast]
  *
- * query-cpus conveys following information:
+ * query-cpus[-fast] conveys following information:
  * - thread id of a given guest logical vcpu
  * - order in which the vcpus were inserted
  * - qom path to allow mapping the two together
@@ -1890,7 +1891,7 @@ qemuMonitorGetCPUInfoHotplug(struct qemuMonitorQueryHotpluggableCpusEntry *hotpl
     for (i = 0; i < nhotplugvcpus; i++)
         totalvcpus += hotplugvcpus[i].vcpus;
 
-    /* trim '/thread...' suffix from the data returned by query-cpus */
+    /* trim '/thread...' suffix from the data returned by query-cpus[-fast] */
     for (i = 0; i < ncpuentries; i++) {
         if (cpuentries[i].qom_path &&
             (tmp = strstr(cpuentries[i].qom_path, "/thread")))
@@ -1903,7 +1904,7 @@ qemuMonitorGetCPUInfoHotplug(struct qemuMonitorQueryHotpluggableCpusEntry *hotpl
     }
 
     /* Note the order in which the hotpluggable entities are inserted by
-     * matching them to the query-cpus entries */
+     * matching them to the query-cpus[-fast] entries */
     for (i = 0; i < ncpuentries; i++) {
         for (j = 0; j < nhotplugvcpus; j++) {
             if (!cpuentries[i].qom_path ||
@@ -1958,7 +1959,7 @@ qemuMonitorGetCPUInfoHotplug(struct qemuMonitorQueryHotpluggableCpusEntry *hotpl
         }
 
         if (anyvcpu == maxvcpus) {
-            VIR_DEBUG("too many query-cpus entries for a given "
+            VIR_DEBUG("too many query-cpus[-fast] entries for a given "
                       "query-hotpluggable-cpus entry");
             return -1;
         }
@@ -1986,6 +1987,7 @@ qemuMonitorGetCPUInfoHotplug(struct qemuMonitorQueryHotpluggableCpusEntry *hotpl
  * @vcpus: pointer filled by array of qemuMonitorCPUInfo structures
  * @maxvcpus: total possible number of vcpus
  * @hotplug: query data relevant for hotplug support
+ * @fast: use QMP query-cpus-fast if supported
  *
  * Detects VCPU information. If qemu doesn't support or fails reporting
  * information this function will return success as other parts of libvirt
@@ -1998,7 +2000,8 @@ int
 qemuMonitorGetCPUInfo(qemuMonitorPtr mon,
                       qemuMonitorCPUInfoPtr *vcpus,
                       size_t maxvcpus,
-                      bool hotplug)
+                      bool hotplug,
+                      bool fast)
 {
     struct qemuMonitorQueryHotpluggableCpusEntry *hotplugcpus = NULL;
     size_t nhotplugcpus = 0;
@@ -2024,7 +2027,8 @@ qemuMonitorGetCPUInfo(qemuMonitorPtr mon,
         goto cleanup;
 
     if (mon->json)
-        rc = qemuMonitorJSONQueryCPUs(mon, &cpuentries, &ncpuentries, hotplug);
+        rc = qemuMonitorJSONQueryCPUs(mon, &cpuentries, &ncpuentries, hotplug,
+                                      fast);
     else
         rc = qemuMonitorTextQueryCPUs(mon, &cpuentries, &ncpuentries);
 
@@ -2062,11 +2066,12 @@ qemuMonitorGetCPUInfo(qemuMonitorPtr mon,
  * qemuMonitorGetCpuHalted:
  *
  * Returns a bitmap of vcpu id's that are halted. The id's correspond to the
- * 'CPU' field as reported by query-cpus'.
+ * 'CPU' field as reported by query-cpus[-fast]'.
  */
 virBitmapPtr
 qemuMonitorGetCpuHalted(qemuMonitorPtr mon,
-                        size_t maxvcpus)
+                        size_t maxvcpus,
+                        bool fast ATTRIBUTE_UNUSED)
 {
     struct qemuMonitorQueryCpusEntry *cpuentries = NULL;
     size_t ncpuentries = 0;
@@ -2077,7 +2082,8 @@ qemuMonitorGetCpuHalted(qemuMonitorPtr mon,
     QEMU_CHECK_MONITOR_NULL(mon);
 
     if (mon->json)
-        rc = qemuMonitorJSONQueryCPUs(mon, &cpuentries, &ncpuentries, false);
+        rc = qemuMonitorJSONQueryCPUs(mon, &cpuentries, &ncpuentries, false,
+                                      false);
     else
         rc = qemuMonitorTextQueryCPUs(mon, &cpuentries, &ncpuentries);
 

src/qemu/qemu_monitor.h

@@ -542,8 +542,11 @@ void qemuMonitorCPUInfoFree(qemuMonitorCPUInfoPtr list,
 int qemuMonitorGetCPUInfo(qemuMonitorPtr mon,
                           qemuMonitorCPUInfoPtr *vcpus,
                           size_t maxvcpus,
-                          bool hotplug);
+                          bool hotplug,
-virBitmapPtr qemuMonitorGetCpuHalted(qemuMonitorPtr mon, size_t maxvcpus);
+                          bool fast);
+virBitmapPtr qemuMonitorGetCpuHalted(qemuMonitorPtr mon,
+                                     size_t maxvcpus,
+                                     bool fast);
 
 int qemuMonitorGetVirtType(qemuMonitorPtr mon,
                            virDomainVirtType *virtType);

src/qemu/qemu_monitor_json.c

@@ -1532,7 +1532,8 @@ int qemuMonitorJSONSystemReset(qemuMonitorPtr mon)
 static int
 qemuMonitorJSONExtractCPUInfo(virJSONValuePtr data,
                               struct qemuMonitorQueryCpusEntry **entries,
-                              size_t *nentries)
+                              size_t *nentries,
+                              bool fast)
 {
     struct qemuMonitorQueryCpusEntry *cpus = NULL;
     int ret = -1;
@@ -1557,11 +1558,19 @@ qemuMonitorJSONExtractCPUInfo(virJSONValuePtr data,
         }
 
         /* Some older qemu versions don't report the thread_id so treat this as
-         * non-fatal, simply returning no data */
+         * non-fatal, simply returning no data.
-        ignore_value(virJSONValueObjectGetNumberInt(entry, "CPU", &cpuid));
+         * The return data of query-cpus-fast has different field names
-        ignore_value(virJSONValueObjectGetNumberInt(entry, "thread_id", &thread));
+         */
-        ignore_value(virJSONValueObjectGetBoolean(entry, "halted", &halted));
+        if (fast) {
-        qom_path = virJSONValueObjectGetString(entry, "qom_path");
+            ignore_value(virJSONValueObjectGetNumberInt(entry, "cpu-index", &cpuid));
+            ignore_value(virJSONValueObjectGetNumberInt(entry, "thread-id", &thread));
+            qom_path = virJSONValueObjectGetString(entry, "qom-path");
+        } else {
+            ignore_value(virJSONValueObjectGetNumberInt(entry, "CPU", &cpuid));
+            ignore_value(virJSONValueObjectGetNumberInt(entry, "thread_id", &thread));
+            ignore_value(virJSONValueObjectGetBoolean(entry, "halted", &halted));
+            qom_path = virJSONValueObjectGetString(entry, "qom_path");
+        }
 
         cpus[i].qemu_id = cpuid;
         cpus[i].tid = thread;
@@ -1586,10 +1595,12 @@ qemuMonitorJSONExtractCPUInfo(virJSONValuePtr data,
  * @mon: monitor object
  * @entries: filled with detected entries on success
  * @nentries: number of entries returned
+ * @force: force exit on error
+ * @fast: use query-cpus-fast
  *
  * Queries qemu for cpu-related information. Failure to execute the command or
  * extract results does not produce an error as libvirt can continue without
- * this information.
+ * this information, unless the caller has specified @force == true.
  *
  * Returns 0 on success, -1 on a fatal error (oom ...) and -2 if the
  * query failed gracefully.
@@ -1598,13 +1609,19 @@ int
 qemuMonitorJSONQueryCPUs(qemuMonitorPtr mon,
                          struct qemuMonitorQueryCpusEntry **entries,
                          size_t *nentries,
-                         bool force)
+                         bool force,
+                         bool fast)
 {
     int ret = -1;
-    virJSONValuePtr cmd = qemuMonitorJSONMakeCommand("query-cpus", NULL);
+    virJSONValuePtr cmd;
     virJSONValuePtr reply = NULL;
     virJSONValuePtr data;
 
+    if (fast)
+        cmd = qemuMonitorJSONMakeCommand("query-cpus-fast", NULL);
+    else
+        cmd = qemuMonitorJSONMakeCommand("query-cpus", NULL);
+
     if (!cmd)
         return -1;
 
@@ -1619,7 +1636,7 @@ qemuMonitorJSONQueryCPUs(qemuMonitorPtr mon,
         goto cleanup;
     }
 
-    ret = qemuMonitorJSONExtractCPUInfo(data, entries, nentries);
+    ret = qemuMonitorJSONExtractCPUInfo(data, entries, nentries, fast);
 
  cleanup:
     virJSONValueFree(cmd);

src/qemu/qemu_monitor_json.h

@@ -60,7 +60,8 @@ int qemuMonitorJSONSystemReset(qemuMonitorPtr mon);
 int qemuMonitorJSONQueryCPUs(qemuMonitorPtr mon,
                              struct qemuMonitorQueryCpusEntry **entries,
                              size_t *nentries,
-                             bool force);
+                             bool force,
+                             bool fast);
 int qemuMonitorJSONGetVirtType(qemuMonitorPtr mon,
                                virDomainVirtType *virtType);
 int qemuMonitorJSONUpdateVideoMemorySize(qemuMonitorPtr mon,

tests/qemumonitorjsontest.c

@@ -1425,7 +1425,7 @@ testQemuMonitorJSONqemuMonitorJSONQueryCPUs(const void *data)
         goto cleanup;
 
     if (qemuMonitorJSONQueryCPUs(qemuMonitorTestGetMonitor(test),
-                                 &cpudata, &ncpudata, true) < 0)
+                                 &cpudata, &ncpudata, true, false) < 0)
         goto cleanup;
 
     if (ncpudata != 4) {
@@ -2638,7 +2638,7 @@ testQemuMonitorCPUInfo(const void *opaque)
         goto cleanup;
 
     rc = qemuMonitorGetCPUInfo(qemuMonitorTestGetMonitor(test),
-                               &vcpus, data->maxvcpus, true);
+                               &vcpus, data->maxvcpus, true, false);
 
     if (rc < 0)
         goto cleanup;