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

On 01/13/2017 05:04 AM, Jiri Denemark wrote: > On Thu, Jan 12, 2017 at 11:18:11 -0500, Collin L. Walling wrote: > > 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(a)linux.vnet.ibm.com&gt; > > Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com&gt; > > Signed-off-by: Jason J. Herne <jjherne(a)linux.vnet.ibm.com&gt; > > --- > > 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. > > + */ > > Hmm, this comment says something a bit different than the commit > message. I hope the issue described by this comment was fixed in QEMU > within the same release the query-cpu-model-expansion command was > introduced. But we need to fix this nevertheless to address what the > commit message describes. > The issue still exists in Qemu. I can work up a patch to handle it. My first idea is to simply test that the ioctl exists and functions at Qemu initialization and deregister the query-cpu-model-expansion command in the event that the ioctl does not exist or fails. Thoughts?