[libvirt PATCH] qemu: fix detection of vCPU pids when multiple dies are present

[Daniel P. Berrangé <berrange@xxxxxxxxxx>]

The logic for querying hotpluggable CPUs needs to sort the list
of CPUs returned by QEMU. Unfortunately our sorting method failed
to use the die_id field, so CPUs were not correctly sorted.

This is seen when configuring a guest with partially populated
CPUs

  <vcpu placement='static' current='1'>16</vcpu>
  <cpu...>
    <topology sockets='4' dies='2' cores='1' threads='2'/>
  </cpu>

Then trying to start it would fail:

  # virsh -c qemu:///system start demo
  error: Failed to start domain demo
  error: internal error: qemu didn't report thread id for vcpu '0'

Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
---
 src/qemu/qemu_domain.c       | 10 ++++++++--
 src/qemu/qemu_monitor.c      |  2 ++
 src/qemu/qemu_monitor.h      |  2 ++
 src/qemu/qemu_monitor_json.c |  4 ++++
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 4b467afa81..acb93d24ae 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -13537,8 +13537,14 @@ qemuDomainRefreshVcpuInfo(virQEMUDriverPtr driver,
         }
 
         if (validTIDs)
-            VIR_DEBUG("vCPU[%zu] PID %llu is valid",
-                      i, (unsigned long long)info[i].tid);
+            VIR_DEBUG("vCPU[%zu] PID %llu is valid "
+                      "(node=%d socket=%d die=%d core=%d thread=%d)",
+                      i, (unsigned long long)info[i].tid,
+                      info[i].node_id,
+                      info[i].socket_id,
+                      info[i].die_id,
+                      info[i].core_id,
+                      info[i].thread_id);
     }
 
     VIR_DEBUG("Extracting vCPU information validTIDs=%d", validTIDs);
diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index e3d621f038..017b818f73 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -1615,6 +1615,7 @@ qemuMonitorCPUInfoClear(qemuMonitorCPUInfoPtr cpus,
         cpus[i].id = 0;
         cpus[i].qemu_id = -1;
         cpus[i].socket_id = -1;
+        cpus[i].die_id = -1;
         cpus[i].core_id = -1;
         cpus[i].thread_id = -1;
         cpus[i].node_id = -1;
@@ -1770,6 +1771,7 @@ qemuMonitorGetCPUInfoHotplug(struct qemuMonitorQueryHotpluggableCpusEntry *hotpl
         vcpus[mastervcpu].hotpluggable = !!hotplugvcpus[i].alias ||
                                          !vcpus[mastervcpu].online;
         vcpus[mastervcpu].socket_id = hotplugvcpus[i].socket_id;
+        vcpus[mastervcpu].die_id = hotplugvcpus[i].die_id;
         vcpus[mastervcpu].core_id = hotplugvcpus[i].core_id;
         vcpus[mastervcpu].thread_id = hotplugvcpus[i].thread_id;
         vcpus[mastervcpu].node_id = hotplugvcpus[i].node_id;
diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index 6ccea909e9..be4195e734 100644
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -561,6 +561,7 @@ struct qemuMonitorQueryHotpluggableCpusEntry {
     /* topology information -1 if qemu didn't report given parameter */
     int node_id;
     int socket_id;
+    int die_id;
     int core_id;
     int thread_id;
 
@@ -583,6 +584,7 @@ struct _qemuMonitorCPUInfo {
     /* topology info for hotplug purposes. Hotplug of given vcpu impossible if
      * all entries are -1 */
     int socket_id;
+    int die_id;
     int core_id;
     int thread_id;
     int node_id;
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 3eac80c060..04affb851f 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -8565,6 +8565,7 @@ qemuMonitorJSONProcessHotpluggableCpusReply(virJSONValuePtr vcpu,
 
     ignore_value(virJSONValueObjectGetNumberInt(props, "node-id", &entry->node_id));
     ignore_value(virJSONValueObjectGetNumberInt(props, "socket-id", &entry->socket_id));
+    ignore_value(virJSONValueObjectGetNumberInt(props, "die-id", &entry->die_id));
     ignore_value(virJSONValueObjectGetNumberInt(props, "core-id", &entry->core_id));
     ignore_value(virJSONValueObjectGetNumberInt(props, "thread-id", &entry->thread_id));
 
@@ -8599,6 +8600,9 @@ qemuMonitorQueryHotpluggableCpusEntrySort(const void *p1,
     if (a->socket_id != b->socket_id)
         return a->socket_id - b->socket_id;
 
+    if (a->die_id != b->die_id)
+        return a->die_id - b->die_id;
+
     if (a->core_id != b->core_id)
         return a->core_id - b->core_id;
 
-- 
2.24.1