[libvirt] [PATCH] qemu: match controller index for LIVE+CONFIG when doing hotplug

[Laine Stump]

An attempt to attach a new scsi controller with both --live and
--config but without specifying an index, e.g.:

  <controller model="virtio-scsi" type="scsi" />

led to this error:

  internal error: Cannot parse controller index -1

This was because unspecified indexes are auto-assigned during
virDomainDefPostParse(), which doesn't happen for hotplugged devices
until after the device has been added to the domainDef, but
qemuDomainAttachFlags() makes a copy of the device (for feeding to
qemuDomainAttachDeviceLive() *before* it's added to the config, and
the copying function actually formats the device object and then
re-parses it into a new object.

Since qemuDomainAttachDeviceConfig() consumes the device object
pointer (i.e. sets it to NULL in the original virDomainDeviceDef) we
can't just wait to make the copy. Instead, we need to make a *shallow*
copy of the virDomainDeviceDef prior to
qemuDomainAttachDeviceConfig(), then make a deep copy of the shallow
copy.

This resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1344899
---
 src/qemu/qemu_driver.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index fa05046..f3e17e2 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -8199,6 +8199,7 @@ qemuDomainAttachDeviceFlags(virDomainPtr dom,
     virDomainObjPtr vm = NULL;
     virDomainDefPtr vmdef = NULL;
     virDomainDeviceDefPtr dev = NULL, dev_copy = NULL;
+    virDomainDeviceDef dev_shallow;
     int ret = -1;
     unsigned int parse_flags = VIR_DOMAIN_DEF_PARSE_INACTIVE |
                                VIR_DOMAIN_DEF_PARSE_ABI_UPDATE;
@@ -8237,22 +8238,19 @@ qemuDomainAttachDeviceFlags(virDomainPtr dom,
     if (dev == NULL)
         goto endjob;
 
-    if (flags & VIR_DOMAIN_AFFECT_CONFIG &&
-        flags & VIR_DOMAIN_AFFECT_LIVE) {
-        /* If we are affecting both CONFIG and LIVE
-         * create a deep copy of device as adding
-         * to CONFIG takes one instance.
-         */
-        dev_copy = virDomainDeviceDefCopy(dev, vm->def, caps, driver->xmlopt);
-        if (!dev_copy)
-            goto endjob;
-    }
-
     if (priv->qemuCaps)
         qemuCaps = virObjectRef(priv->qemuCaps);
     else if (!(qemuCaps = virQEMUCapsCacheLookup(driver->qemuCapsCache, vm->def->emulator)))
         goto endjob;
 
+    /* Save away the pointer to the device object before it is
+     * potentially swallowed up by qemuDomainAttachDeviceConfig().
+     * This will allow us to make a copy of the device after any
+     * modifications made by virDomainDefPostParse() (which is called
+     * after the new device is added to the config
+     */
+    dev_shallow = *dev;
+
     if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
         /* Make a copy for updated domain. */
         vmdef = virDomainObjCopyPersistentDef(vm, caps, driver->xmlopt);
@@ -8270,6 +8268,17 @@ qemuDomainAttachDeviceFlags(virDomainPtr dom,
     }
 
     if (flags & VIR_DOMAIN_AFFECT_LIVE) {
+        if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
+            /* If we are affecting both CONFIG and LIVE create a deep
+             * copy of device from the saved shallow copy, as adding
+             * it to CONFIG has already consumed the original.
+             */
+            dev_copy = virDomainDeviceDefCopy(&dev_shallow, vm->def,
+                                              caps, driver->xmlopt);
+            if (!dev_copy)
+                goto endjob;
+        }
+
         if (virDomainDefCompatibleDevice(vm->def, dev_copy,
                                          VIR_DOMAIN_DEVICE_ACTION_ATTACH) < 0)
             goto endjob;
-- 
2.5.5