Bug 872292

Affected are:
cpu_set in qemuMonitorJSONSetCPU()
host_net_add in qemuMonitorJSONAddHostNetwork()
host_net_remove in qemuMonitorJSONRemoveHostNetwork()
drive_add in qemuMonitorJSONAttachDrive() and qemuMonitorJSONAddDrive()
drive_del in qemuMonitorJSONDriveDel()
savevm in qemuMonitorJSONCreateSnapshot()
loadvm in qemuMonitorJSONLoadSnapshot()
delvm in qemuMonitorJSONDeleteSnapshot()

Upstream patch proposed.
https://www.redhat.com/archives/libvir-list/2012-November/msg01474.html

commit 3d7f6649e87945a39808bf3ba4e7cec5df8fc13c
Author: Eric Blake <eblake>
Date:   Thu Nov 29 17:35:23 2012 -0700

    qemu: don't attempt undefined QMP commands
    
    https://bugzilla.redhat.com/show_bug.cgi?id=872292
    
    Libvirt should not attempt to call a QMP command that has not been
    documented in qemu.git - if future qemu introduces a command by the
    same name but with subtly different semantics, then libvirt will be
    broken when trying to use that command.
    
    We also had some code that could never be reached - some of our
    commands have an alternate for new vs. old qemu HMP commands; but
    if we are new enough to support QMP, we only need a fallback to
    the new HMP counterpart, and don't need to try for a QMP counterpart
    for the old HMP version.
    
    See also this attempt to convert the three snapshot commands to QMP:
    https://lists.gnu.org/archive/html/qemu-devel/2012-07/msg01597.html
    although it looks like that will still not happen before qemu 1.3.
    That thread eventually decided that qemu would use the name
    'save-vm' rather than 'savevm', which mitigates the fact that
    libvirt's attempt to use a QMP 'savevm' would be broken, but we
    might not be as lucky on the other commands.
    
    * src/qemu/qemu_monitor_json.c (qemuMonitorJSONSetCPU)
    (qemuMonitorJSONAddDrive, qemuMonitorJSONDriveDel)
    (qemuMonitorJSONCreateSnapshot, qemuMonitorJSONLoadSnapshot)
    (qemuMonitorJSONDeleteSnapshot): Use only HMP fallback for now.
    (qemuMonitorJSONAddHostNetwork, qemuMonitorJSONRemoveHostNetwork)
    (qemuMonitorJSONAttachDrive, qemuMonitorJSONGetGuestDriveAddress):
    Delete; QMP implies QEMU_CAPS_DEVICE, which prefers AddNetdev,
    RemoveNetdev, and AddDrive anyways (qemu_hotplug.c has all callers).
    * src/qemu/qemu_monitor.c (qemuMonitorAddHostNetwork)
    (qemuMonitorRemoveHostNetwork, qemuMonitorAttachDrive): Reflect
    deleted commands.
    * src/qemu/qemu_monitor_json.h (qemuMonitorJSONAddHostNetwork)
    (qemuMonitorJSONRemoveHostNetwork, qemuMonitorJSONAttachDrive):
    Likewise.

Verify this bug :
libvirt-1.0.1-1.el7.x86_64

1)

edit /etc/libvirt/libvirtd.cfg

log_level = 1

log_filters="1:json 3:remote 4:event"

log_outputs="1:file:/tmp/libvirtd.log"


2) service libvirtd restart


3) start a guest then create system checkpointing snapshot 

#virsh snapshot-create  domain s1

4) check /tmp/libvirtd.log  about savevm 

2012-12-20 06:00:51.093+0000: 9788: debug : qemuMonitorJSONCreateSnapshot:2940 : savevm command not found, trying HMP
2012-12-20 06:00:51.093+0000: 9788: debug : virJSONValueToString:1068 : object=0x7f0cf40984c0
2012-12-20 06:00:51.093+0000: 9788: debug : virJSONValueToStringOne:999 : object=0x7f0cf40984c0 type=0 gen=0x7f0cf40cdc50
2012-12-20 06:00:51.093+0000: 9788: debug : virJSONValueToStringOne:999 : object=0x7f0cf417edd0 type=2 gen=0x7f0cf40cdc50
2012-12-20 06:00:51.093+0000: 9788: debug : virJSONValueToStringOne:999 : object=0x7f0cf40dedd0 type=0 gen=0x7f0cf40cdc50
2012-12-20 06:00:51.093+0000: 9788: debug : virJSONValueToStringOne:999 : object=0x7f0cf40172a0 type=2 gen=0x7f0cf40cdc50
2012-12-20 06:00:51.093+0000: 9788: debug : virJSONValueToStringOne:999 : object=0x7f0cf400f1b0 type=2 gen=0x7f0cf40cdc50
2012-12-20 06:00:51.093+0000: 9788: debug : virJSONValueToString:1102 : result={"execute":"human-monitor-command","arguments":{"command-line":"savevm \"s3\""},"id":"libvirt-7"}
2012-12-20 06:00:51.093+0000: 9788: debug : qemuMonitorJSONCommandWithFd:261 : Send command '{"execute":"human-monitor-command","arguments":{"command-line":"savevm \"s3\""},"id":"libvirt-7"}' for write with FD -1
2012-12-20 06:00:51.093+0000: 9788: debug : qemuMonitorSend:904 : QEMU_MONITOR_SEND_MSG: mon=0x7f0cec000d00 msg={"execute":"human-monitor-command","arguments":{"command-line":"savevm \"s3\""},"id":"libvirt-7"}^M
 fd=-1
2012-12-20 06:00:51.093+0000: 9783: debug : virObjectRef:168 : OBJECT_REF: obj=0x7f0cec000d00
2012-12-20 06:00:51.093+0000: 9783: debug : qemuMonitorIOWrite:462 : QEMU_MONITOR_IO_WRITE: mon=0x7f0cec000d00 buf={"execute":"human-monitor-command","arguments":{"command-line":"savevm \"s3\""},"id":"libvirt-7"}^M

This request was resolved in Red Hat Enterprise Linux 7.0.

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