From a88c65e490d45e73715823b455799a58869ddd0e Mon Sep 17 00:00:00 2001
From: Peter Krempa <pkrempa@redhat.com>
Date: Wed, 21 Sep 2016 07:59:57 +0200
Subject: [PATCH] qemu: vcpu: Clear vcpu order information rather than making
 it invalid

Certain operations may make the vcpu order information invalid. Since
the order is primarily used to ensure migration compatibility and has
basically no other user benefits, clear the order prior to certain
operations and document that it may be cleared.

All the operations that would clear the order can still be properly
executed by defining a new domain configuration rather than using the
helper APIs.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1370357
---
 docs/formatdomain.html.in |  3 ++-
 src/conf/domain_conf.c    | 10 ++++++++++
 src/conf/domain_conf.h    |  1 +
 src/libvirt_private.syms  |  1 +
 src/qemu/qemu_driver.c    |  5 +++++
 5 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 513bc0efc3..1266e9d164 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -569,7 +569,8 @@
         the order may be be duplicated accross all vcpus that need to be
         enabled at once. Specifying order is not necessary, vcpus are then
         added in an arbitrary order. If order info is used, it must be used for
-        all online vcpus.
+        all online vcpus. Hypervisors may clear or update ordering information
+        during certain operations to assure valid configuration.
 
         Note that hypervisors may create hotpluggable vcpus differently from
         boot vcpus thus special initialization may be necessary.
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 7972a4eac2..920529a76d 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -25566,3 +25566,13 @@ virDomainGetBlkioParametersAssignFromDef(virDomainDefPtr def,
     virBufferFreeAndReset(&buf);
     return -1;
 }
+
+
+void
+virDomainDefVcpuOrderClear(virDomainDefPtr def)
+{
+    size_t i;
+
+    for (i = 0; i < def->maxvcpus; i++)
+        def->vcpus[i]->order = 0;
+}
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 561a179e63..fd3ae8e500 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2487,6 +2487,7 @@ unsigned int virDomainDefGetVcpus(const virDomainDef *def);
 virBitmapPtr virDomainDefGetOnlineVcpumap(const virDomainDef *def);
 virDomainVcpuDefPtr virDomainDefGetVcpu(virDomainDefPtr def, unsigned int vcpu)
     ATTRIBUTE_RETURN_CHECK;
+void virDomainDefVcpuOrderClear(virDomainDefPtr def);
 
 virDomainObjPtr virDomainObjNew(virDomainXMLOptionPtr caps)
     ATTRIBUTE_NONNULL(1);
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 68d0ea973f..eae817d14d 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -264,6 +264,7 @@ virDomainDefSetMemoryTotal;
 virDomainDefSetVcpus;
 virDomainDefSetVcpusMax;
 virDomainDefValidate;
+virDomainDefVcpuOrderClear;
 virDomainDeleteConfig;
 virDomainDeviceAddressIsValid;
 virDomainDeviceAddressTypeToString;
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 487bafc7d6..12ddbc0c9a 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -4745,6 +4745,9 @@ qemuDomainSetVcpusMax(virQEMUDriverPtr driver,
         }
     }
 
+    /* ordering information may become invalid, thus clear it */
+    virDomainDefVcpuOrderClear(persistentDef);
+
     if (virDomainDefSetVcpusMax(persistentDef, nvcpus, driver->xmlopt) < 0)
         goto cleanup;
 
@@ -4919,6 +4922,8 @@ qemuDomainSetVcpusConfig(virDomainDefPtr def,
     size_t maxvcpus = virDomainDefGetVcpusMax(def);
     size_t i;
 
+    /* ordering information may become invalid, thus clear it */
+    virDomainDefVcpuOrderClear(def);
 
     if (curvcpus == nvcpus)
         return;