[libvirt] [PATCH 4/4] qemu: Stop domain on failed restore

[Michal Privoznik]

When resuming a domain from a save file, we read the domain XML
from the file, add it onto our internal list of domains, start
the qemu process, let it load the incoming migration stream and
resume its vCPUs afterwards. If anything goes wrong, the domain
object is removed from the list of domains and error is returned
to the caller. However, the qemu process might be left behind -
if resuming vCPUs fails (e.g. because qemu is unable to acquire
write lock on a disk) then due to a bug the qemu process is not
killed but the domain object is removed from the list.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1718707

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/qemu/qemu_driver.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index ce9b1772c1..217d873671 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -6800,7 +6800,7 @@ qemuDomainSaveImageStartVM(virConnectPtr conn,
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
     int ret = -1;
-    bool restored = false;
+    bool started = false;
     virObjectEventPtr event;
     VIR_AUTOCLOSE intermediatefd = -1;
     g_autoptr(virCommand) cmd = NULL;
@@ -6808,6 +6808,7 @@ qemuDomainSaveImageStartVM(virConnectPtr conn,
     g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
     virQEMUSaveHeaderPtr header = &data->header;
     g_autoptr(qemuDomainSaveCookie) cookie = NULL;
+    int rc = 0;
 
     if (virSaveCookieParseString(data->cookie, (virObjectPtr *)&cookie,
                                  virDomainXMLOptionGetSaveCookie(driver->xmlopt)) < 0)
@@ -6848,12 +6849,12 @@ qemuDomainSaveImageStartVM(virConnectPtr conn,
                          VIR_NETDEV_VPORT_PROFILE_OP_RESTORE,
                          VIR_QEMU_PROCESS_START_PAUSED |
                          VIR_QEMU_PROCESS_START_GEN_VMID) == 0)
-        restored = true;
+        started = true;
 
     if (intermediatefd != -1) {
         virErrorPtr orig_err = NULL;
 
-        if (!restored) {
+        if (!started) {
             /* if there was an error setting up qemu, the intermediate
              * process will wait forever to write to stdout, so we
              * must manually kill it and ignore any error related to
@@ -6864,21 +6865,17 @@ qemuDomainSaveImageStartVM(virConnectPtr conn,
             VIR_FORCE_CLOSE(*fd);
         }
 
-        if (virCommandWait(cmd, NULL) < 0) {
-            qemuProcessStop(driver, vm, VIR_DOMAIN_SHUTOFF_FAILED, asyncJob, 0);
-            restored = false;
-        }
+        rc = virCommandWait(cmd, NULL);
         VIR_DEBUG("Decompression binary stderr: %s", NULLSTR(errbuf));
-
         virErrorRestore(&orig_err);
     }
     if (VIR_CLOSE(*fd) < 0) {
         virReportSystemError(errno, _("cannot close file: %s"), path);
-        restored = false;
+        rc = -1;
     }
 
-    virDomainAuditStart(vm, "restored", restored);
-    if (!restored)
+    virDomainAuditStart(vm, "restored", started);
+    if (!started || rc < 0)
         goto cleanup;
 
     /* qemuProcessStart doesn't unset the qemu error reporting infrastructure
@@ -6918,6 +6915,10 @@ qemuDomainSaveImageStartVM(virConnectPtr conn,
     ret = 0;
 
  cleanup:
+    if (ret < 0 && started) {
+        qemuProcessStop(driver, vm, VIR_DOMAIN_SHUTOFF_FAILED,
+                        asyncJob, VIR_QEMU_PROCESS_STOP_MIGRATED);
+    }
     if (qemuSecurityRestoreSavedStateLabel(driver, vm, path) < 0)
         VIR_WARN("failed to restore save state label on %s", path);
     return ret;
-- 
2.24.1