add --live support to "virsh dump"

This is trivial for QEMU since you just have to not stop the vm before
starting the dump.  And for Xen, you just pass the flag down to xend.

* include/libvirt/libvirt.h.in (virDomainCoreDumpFlags): Add VIR_DUMP_LIVE.
* src/qemu/qemu_driver.c (qemudDomainCoreDump): Support live dumping.
* src/xen/xend_internal.c (xenDaemonDomainCoreDump): Support live dumping.
* tools/virsh.c (opts_dump): Add --live. (cmdDump): Map it to VIR_DUMP_LIVE.

include/libvirt/libvirt.h.in

@@ -337,6 +337,7 @@ typedef virDomainInterfaceStatsStruct *virDomainInterfaceStatsPtr;
 /* Domain core dump flags. */
 typedef enum {
     VIR_DUMP_CRASH   = (1 << 0), /* crash after dump */
+    VIR_DUMP_LIVE    = (1 << 1), /* live dump */
 } virDomainCoreDumpFlags;
 
 /* Domain migration flags. */

src/qemu/qemu_driver.c

@@ -3856,15 +3856,14 @@ static int qemudDomainCoreDump(virDomainPtr dom,
         driver->securityDriver->domainSetSavedStateLabel(dom->conn, vm, path) == -1)
         goto endjob;
 
-    /* Migrate will always stop the VM, so once we support live dumping
-       the resume condition will stay the same, independent of whether
-       the stop command is issued.  */
+    /* Migrate will always stop the VM, so the resume condition is
+       independent of whether the stop command is issued.  */
     resume = (vm->state == VIR_DOMAIN_RUNNING);
 
     qemuDomainObjPrivatePtr priv = vm->privateData;
 
     /* Pause domain for non-live dump */
-    if (vm->state == VIR_DOMAIN_RUNNING) {
+    if (!(flags & VIR_DUMP_LIVE) && vm->state == VIR_DOMAIN_RUNNING) {
         qemuDomainObjEnterMonitor(vm);
         if (qemuMonitorStopCPUs(priv->mon) < 0) {
             qemuDomainObjExitMonitor(vm);

src/xen/xend_internal.c

@@ -3255,6 +3255,7 @@ xenDaemonDomainCoreDump(virDomainPtr domain, const char *filename,
 
     return xend_op(domain->conn, domain->name,
                    "op", "dump", "file", filename, "live", "0",
+                   "live", (flags & VIR_DUMP_LIVE ? "1" : "0"),
                    "crash", (flags & VIR_DUMP_CRASH ? "1" : "0"),
                    NULL);
 }

tools/virsh.c

@@ -1431,6 +1431,7 @@ static const vshCmdInfo info_dump[] = {
 };
 
 static const vshCmdOptDef opts_dump[] = {
+    {"live", VSH_OT_BOOL, 0, gettext_noop("perform a live core dump if supported")},
     {"crash", VSH_OT_BOOL, 0, gettext_noop("crash the domain after core dump")},
     {"domain", VSH_OT_DATA, VSH_OFLAG_REQ, gettext_noop("domain name, id or uuid")},
     {"file", VSH_OT_DATA, VSH_OFLAG_REQ, gettext_noop("where to dump the core")},
@@ -1455,6 +1456,8 @@ cmdDump(vshControl *ctl, const vshCmd *cmd)
     if (!(dom = vshCommandOptDomain(ctl, cmd, &name)))
         return FALSE;
 
+    if (vshCommandOptBool (cmd, "live"))
+        flags |= VIR_DUMP_LIVE;
     if (vshCommandOptBool (cmd, "crash"))
         flags |= VIR_DUMP_CRASH;