[libvirt] [PATCH] qemu-capabilities: Fix query-cpu-model-expansion on s390 with older kernel

[Collin L. Walling]

When running on s390 with a kernel that does not support cpu model checking and
with a Qemu new enough to support query-cpu-model-expansion, the gathering of qemu
capabilities will fail. Qemu responds to the query-cpu-model-expansion qmp
command with an error because the needed kernel ioct does not exist. When this
happens a guest cannot even be defined due to missing qemu capabilities data.

This patch fixes the problem by silently ignoring generic errors stemming from
calls to query-cpu-model-expansion.

Reported-by: Farhan Ali <alifm at linux.vnet.ibm.com>
Signed-off-by: Collin L. Walling <walling at linux.vnet.ibm.com>
Signed-off-by: Jason J. Herne <jjherne at linux.vnet.ibm.com>
---
 src/qemu/qemu_monitor_json.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index e767437..1662749 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -5041,6 +5041,15 @@ qemuMonitorJSONGetCPUModelExpansion(qemuMonitorPtr mon,
     if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
         goto cleanup;
 
+    /* Some QEMU architectures have the query-cpu-model-expansion
+     * command, but return 'GenericError' instead of simply omitting
+     * the command entirely.
+     */
+    if (qemuMonitorJSONHasError(reply, "GenericError")) {
+        ret = 0;
+        goto cleanup;
+    }
+
     if (qemuMonitorJSONCheckError(cmd, reply) < 0)
         goto cleanup;
 
-- 
2.7.4