[libvirt] [PATCH] qemu: capabilities: Don't partially reprope caps on process reconnect

[Peter Krempa]

Thanks to the complex capability caching code virQEMUCapsProbeQMP was
never called when we were starting a new qemu VM. On the other hand,
when we are reconnecting to the qemu process we reload the capability
list from the status XML file. This means that the flag preventing the
function being called was not set and thus we partially reprobed some of
the capabilities.

The recent addition of CPU hotplug clears the
QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS if the machine does not support it.
The partial re-probe on reconnect results into attempting to call the
unsupported command and then killing the VM.

Remove the partial reprobe and depend on the stored capabilities. If it
will be necessary to reprobe the capabilities in the future, we should
do a full reprobe rather than this partial one.
---
 src/qemu/qemu_capabilities.c | 17 -----------------
 src/qemu/qemu_capabilities.h |  3 ---
 src/qemu/qemu_process.c      |  4 ----
 3 files changed, 24 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 8901e7b..37e5302 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -2937,23 +2937,6 @@ virQEMUCapsProbeQMPGICCapabilities(virQEMUCapsPtr qemuCaps,
     return 0;
 }

-int virQEMUCapsProbeQMP(virQEMUCapsPtr qemuCaps,
-                        qemuMonitorPtr mon)
-{
-    VIR_DEBUG("qemuCaps=%p mon=%p", qemuCaps, mon);
-
-    if (qemuCaps->usedQMP)
-        return 0;
-
-    if (virQEMUCapsProbeQMPCommands(qemuCaps, mon) < 0)
-        return -1;
-
-    if (virQEMUCapsProbeQMPEvents(qemuCaps, mon) < 0)
-        return -1;
-
-    return 0;
-}
-

 static bool
 virQEMUCapsCPUFilterFeatures(const char *name,
diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
index 5255815..be71507 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -403,9 +403,6 @@ virQEMUCapsPtr virQEMUCapsNew(void);
 int virQEMUCapsInitQMPMonitor(virQEMUCapsPtr qemuCaps,
                               qemuMonitorPtr mon);

-int virQEMUCapsProbeQMP(virQEMUCapsPtr qemuCaps,
-                        qemuMonitorPtr mon);
-
 void virQEMUCapsSet(virQEMUCapsPtr qemuCaps,
                     virQEMUCapsFlags flag) ATTRIBUTE_NONNULL(1);

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index ab0c2c8..90f1101 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -1723,10 +1723,6 @@ qemuConnectMonitor(virQEMUDriverPtr driver, virDomainObjPtr vm, int asyncJob,
     if (qemuMonitorSetCapabilities(priv->mon) < 0)
         goto cleanup;

-    if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_MONITOR_JSON) &&
-        virQEMUCapsProbeQMP(priv->qemuCaps, priv->mon) < 0)
-        goto cleanup;
-
     if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_MIGRATION_EVENT) &&
         qemuMonitorSetMigrationCapability(priv->mon,
                                           QEMU_MONITOR_MIGRATION_CAPS_EVENTS,
-- 
2.10.2