[libvirt] [PATCH] qemu: Introduce qemuDomainDefCheckABIStability

[Michal Privoznik]

https://bugzilla.redhat.com/show_bug.cgi?id=994364

Whenever we check for ABI stability, we have new xml (e.g. provided by
user, or obtained from snapshot, whatever) which we compare to old xml
and see if ABI won't break. However, if the new xml was produced via
virDomainGetXMLDesc(..., VIR_DOMAIN_XML_MIGRATABLE) it lacks some
devices, e.g. 'pci-root' controller. Hence, the ABI stability check
fails even though it is stable. Moreover, we can't simply fix
virDomainDefCheckABIStability because removing the correct devices is
task for the driver. For instance, qemu driver wants to remove the usb
controller too, while LXC driver doesn't. That's why we need special
qemu wrapper over virDomainDefCheckABIStability which removes the
correct devices from domain XML, produces MIGRATABLE xml and calls the
check ABI stability function.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/qemu/qemu_domain.c    | 22 ++++++++++++++++++++++
 src/qemu/qemu_domain.h    |  3 +++
 src/qemu/qemu_driver.c    | 10 ++--------
 src/qemu/qemu_migration.c |  4 ++--
 4 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 968e323..f3e2ba1 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -2342,3 +2342,25 @@ qemuDomainUpdateDeviceList(virQEMUDriverPtr driver,
     priv->qemuDevices = aliases;
     return 0;
 }
+
+bool
+qemuDomainDefCheckABIStability(virQEMUDriverPtr driver,
+                               virDomainDefPtr src,
+                               virDomainDefPtr dst)
+{
+    virDomainDefPtr migratableDefSrc = NULL;
+    virDomainDefPtr migratableDefDst = NULL;
+    const int flags = VIR_DOMAIN_XML_SECURE | VIR_DOMAIN_XML_UPDATE_CPU | VIR_DOMAIN_XML_MIGRATABLE;
+    bool ret = false;
+
+    if (!(migratableDefSrc = qemuDomainDefCopy(driver, src, flags)) ||
+        !(migratableDefDst = qemuDomainDefCopy(driver, dst, flags)))
+        goto cleanup;
+
+    ret = virDomainDefCheckABIStability(migratableDefSrc, migratableDefDst);
+
+cleanup:
+    virDomainDefFree(migratableDefSrc);
+    virDomainDefFree(migratableDefDst);
+    return ret;
+}
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 21f116c..5d9fab9 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -368,4 +368,7 @@ extern virDomainDefParserConfig virQEMUDriverDomainDefParserConfig;
 int qemuDomainUpdateDeviceList(virQEMUDriverPtr driver,
                                virDomainObjPtr vm);
 
+bool qemuDomainDefCheckABIStability(virQEMUDriverPtr driver,
+                                    virDomainDefPtr src,
+                                    virDomainDefPtr dst);
 #endif /* __QEMU_DOMAIN_H__ */
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index c71aecc..8481591 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -3077,7 +3077,7 @@ qemuDomainSaveInternal(virQEMUDriverPtr driver, virDomainPtr dom,
                                             VIR_DOMAIN_XML_INACTIVE))) {
             goto endjob;
         }
-        if (!virDomainDefCheckABIStability(vm->def, def)) {
+        if (!qemuDomainDefCheckABIStability(driver, vm->def, def)) {
             virDomainDefFree(def);
             goto endjob;
         }
@@ -12889,7 +12889,6 @@ static int qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
     qemuDomainObjPrivatePtr priv;
     int rc;
     virDomainDefPtr config = NULL;
-    virDomainDefPtr migratableDef = NULL;
     virQEMUDriverConfigPtr cfg = NULL;
     virCapsPtr caps = NULL;
 
@@ -13006,11 +13005,7 @@ static int qemuDomainRevertToSnapshot(virDomainSnapshotPtr snapshot,
             /* Transitions 5, 6, 8, 9 */
             /* Check for ABI compatibility. We need to do this check against
              * the migratable XML or it will always fail otherwise */
-            if (!(migratableDef = qemuDomainDefCopy(driver, vm->def,
-                                                    VIR_DOMAIN_XML_MIGRATABLE)))
-                goto cleanup;
-
-            if (config && !virDomainDefCheckABIStability(migratableDef, config)) {
+            if (config && !qemuDomainDefCheckABIStability(driver, vm->def, config)) {
                 virErrorPtr err = virGetLastError();
 
                 if (!(flags & VIR_DOMAIN_SNAPSHOT_REVERT_FORCE)) {
@@ -13215,7 +13210,6 @@ cleanup:
     }
     if (vm)
         virObjectUnlock(vm);
-    virDomainDefFree(migratableDef);
     virObjectUnref(caps);
     virObjectUnref(cfg);
 
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 3a1aab7..59fd263 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -2039,7 +2039,7 @@ static char
                                             VIR_DOMAIN_XML_INACTIVE)))
             goto cleanup;
 
-        if (!virDomainDefCheckABIStability(vm->def, def))
+        if (!qemuDomainDefCheckABIStability(driver, vm->def, def))
             goto cleanup;
 
         rv = qemuDomainDefFormatLive(driver, def, false, true);
@@ -2242,7 +2242,7 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
                 if (!newdef)
                     goto cleanup;
 
-                if (!virDomainDefCheckABIStability(*def, newdef)) {
+                if (!qemuDomainDefCheckABIStability(driver, *def, newdef)) {
                     virDomainDefFree(newdef);
                     goto cleanup;
                 }
-- 
1.8.1.5