From 48e3d42889dcf3f7cec24c0bf4fd55c8da5f324b Mon Sep 17 00:00:00 2001
From: Peter Krempa <pkrempa@redhat.com>
Date: Thu, 4 Aug 2016 13:57:46 +0200
Subject: [PATCH] qemu: migration: Prepare for non-contiguous vcpu
 configurations

Introduce a new migration cookie flag that will be used for any
configurations that are not compatible with libvirt that would not
support the specific vcpu hotplug approach. This will make sure that old
libvirt does not fail to reproduce the configuration correctly.
---
 src/qemu/qemu_domain.c    | 35 +++++++++++++++++++++++++++++++++++
 src/qemu/qemu_domain.h    |  3 +++
 src/qemu/qemu_migration.c | 16 ++++++++++++++--
 3 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 5f4c642143..69e1e381be 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -5964,3 +5964,38 @@ qemuDomainPrepareChannel(virDomainChrDefPtr channel,
 
     return 0;
 }
+
+
+/**
+ * qemuDomainVcpuHotplugIsInOrder:
+ * @def: domain definition
+ *
+ * Returns true if online vcpus were added in order (clustered behind vcpu0
+ * with increasing order).
+ */
+bool
+qemuDomainVcpuHotplugIsInOrder(virDomainDefPtr def)
+{
+    size_t maxvcpus = virDomainDefGetVcpusMax(def);
+    virDomainVcpuDefPtr vcpu;
+    unsigned int prevorder = 0;
+    size_t seenonlinevcpus = 0;
+    size_t i;
+
+    for (i = 0; i < maxvcpus; i++) {
+        vcpu = virDomainDefGetVcpu(def, i);
+
+        if (!vcpu->online)
+            break;
+
+        if (vcpu->order < prevorder)
+            break;
+
+        if (vcpu->order > prevorder)
+            prevorder = vcpu->order;
+
+        seenonlinevcpus++;
+    }
+
+    return seenonlinevcpus == virDomainDefGetVcpus(def);
+}
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index b4b3daef36..b873a8b49b 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -722,4 +722,7 @@ int qemuDomainPrepareChannel(virDomainChrDefPtr chr,
                              const char *domainChannelTargetDir)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2);
 
+bool qemuDomainVcpuHotplugIsInOrder(virDomainDefPtr def)
+    ATTRIBUTE_NONNULL(1);
+
 #endif /* __QEMU_DOMAIN_H__ */
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index cf2125d5d3..e451ef6f87 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -92,6 +92,7 @@ enum qemuMigrationCookieFlags {
     QEMU_MIGRATION_COOKIE_FLAG_NBD,
     QEMU_MIGRATION_COOKIE_FLAG_STATS,
     QEMU_MIGRATION_COOKIE_FLAG_MEMORY_HOTPLUG,
+    QEMU_MIGRATION_COOKIE_FLAG_CPU_HOTPLUG,
 
     QEMU_MIGRATION_COOKIE_FLAG_LAST
 };
@@ -105,7 +106,8 @@ VIR_ENUM_IMPL(qemuMigrationCookieFlag,
               "network",
               "nbd",
               "statistics",
-              "memory-hotplug");
+              "memory-hotplug",
+              "cpu-hotplug");
 
 enum qemuMigrationCookieFeatures {
     QEMU_MIGRATION_COOKIE_GRAPHICS  = (1 << QEMU_MIGRATION_COOKIE_FLAG_GRAPHICS),
@@ -115,6 +117,7 @@ enum qemuMigrationCookieFeatures {
     QEMU_MIGRATION_COOKIE_NBD = (1 << QEMU_MIGRATION_COOKIE_FLAG_NBD),
     QEMU_MIGRATION_COOKIE_STATS = (1 << QEMU_MIGRATION_COOKIE_FLAG_STATS),
     QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG = (1 << QEMU_MIGRATION_COOKIE_FLAG_MEMORY_HOTPLUG),
+    QEMU_MIGRATION_COOKIE_CPU_HOTPLUG = (1 << QEMU_MIGRATION_COOKIE_FLAG_CPU_HOTPLUG),
 };
 
 typedef struct _qemuMigrationCookieGraphics qemuMigrationCookieGraphics;
@@ -1408,6 +1411,9 @@ qemuMigrationBakeCookie(qemuMigrationCookiePtr mig,
     if (flags & QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG)
         mig->flagsMandatory |= QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG;
 
+    if (flags & QEMU_MIGRATION_COOKIE_CPU_HOTPLUG)
+        mig->flagsMandatory |= QEMU_MIGRATION_COOKIE_CPU_HOTPLUG;
+
     if (!(*cookieout = qemuMigrationCookieXMLFormatStr(driver, mig)))
         return -1;
 
@@ -3191,6 +3197,11 @@ qemuMigrationBeginPhase(virQEMUDriverPtr driver,
          vm->newDef && virDomainDefHasMemoryHotplug(vm->newDef)))
         cookieFlags |= QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG;
 
+    if (!qemuDomainVcpuHotplugIsInOrder(vm->def) ||
+        ((flags & VIR_MIGRATE_PERSIST_DEST) &&
+         vm->newDef && !qemuDomainVcpuHotplugIsInOrder(vm->newDef)))
+        cookieFlags |= QEMU_MIGRATION_COOKIE_CPU_HOTPLUG;
+
     if (!(mig = qemuMigrationEatCookie(driver, vm, NULL, 0, 0)))
         goto cleanup;
 
@@ -3686,7 +3697,8 @@ qemuMigrationPrepareAny(virQEMUDriverPtr driver,
     if (!(mig = qemuMigrationEatCookie(driver, vm, cookiein, cookieinlen,
                                        QEMU_MIGRATION_COOKIE_LOCKSTATE |
                                        QEMU_MIGRATION_COOKIE_NBD |
-                                       QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG)))
+                                       QEMU_MIGRATION_COOKIE_MEMORY_HOTPLUG |
+                                       QEMU_MIGRATION_COOKIE_CPU_HOTPLUG)))
         goto cleanup;
 
     if (STREQ_NULLABLE(protocol, "rdma") &&