[PATCH 2/6] Added public API to enable post-copy migration

[Cristian Klein <cristian.klein@xxxxxxxxx>]

Added a new `libvirt` migration flag `VIR_MIGRATE_POSTCOPY` and the
necessary code to pass this flag to qemu as migration capability.

Signed-off-by: Cristian Klein <cristian.klein@xxxxxxxxx>
---
 include/libvirt/libvirt.h.in |  1 +
 src/libvirt.c                |  7 +++++++
 src/qemu/qemu_migration.c    | 43 +++++++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_migration.h    |  3 ++-
 4 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
index 6371b7b..bdc33c6 100644
--- a/include/libvirt/libvirt.h.in
+++ b/include/libvirt/libvirt.h.in
@@ -1225,6 +1225,7 @@ typedef enum {
     VIR_MIGRATE_ABORT_ON_ERROR    = (1 << 12), /* abort migration on I/O errors happened during migration */
     VIR_MIGRATE_AUTO_CONVERGE     = (1 << 13), /* force convergence */
     VIR_MIGRATE_RDMA_PIN_ALL      = (1 << 14), /* RDMA memory pinning */
+    VIR_MIGRATE_POSTCOPY          = (1 << 15), /* enable (but don't start) post-copy */
 } virDomainMigrateFlags;
 
 
diff --git a/src/libvirt.c b/src/libvirt.c
index 1a285ca..33aeafa 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -5265,6 +5265,7 @@ virDomainMigrateDirect(virDomainPtr domain,
  *                                 automatically when supported).
  *   VIR_MIGRATE_UNSAFE    Force migration even if it is considered unsafe.
  *   VIR_MIGRATE_OFFLINE Migrate offline
+ *   VIR_MIGRATE_POSTCOPY Enable (but don't start) post-copy
  *
  * VIR_MIGRATE_TUNNELLED requires that VIR_MIGRATE_PEER2PEER be set.
  * Applications using the VIR_MIGRATE_PEER2PEER flag will probably
@@ -5291,6 +5292,12 @@ virDomainMigrateDirect(virDomainPtr domain,
  * can use either VIR_MIGRATE_NON_SHARED_DISK or
  * VIR_MIGRATE_NON_SHARED_INC as they are mutually exclusive.
  *
+ * If you want to enable post-copy migration you must set the
+ * VIR_MIGRATE_POSTCOPY flag. Once migration is active, you may
+ * start post-copy by calling virDomainMigrateStartPostCopy.
+ * When to start post-copy is entirely left to the user, libvirt
+ * only implements the necessary mechanism.
+ *
  * In either case it is typically only necessary to specify a
  * URI if the destination host has multiple interfaces and a
  * specific interface is required to transmit migration data.
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index a5bd825..bd1f2d6 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -1799,6 +1799,45 @@ qemuMigrationSetOffline(virQEMUDriverPtr driver,
 
 
 static int
+qemuMigrationSetPostCopy(virQEMUDriverPtr driver,
+                            virDomainObjPtr vm,
+                            qemuDomainAsyncJob job)
+{
+    qemuDomainObjPrivatePtr priv = vm->privateData;
+    int ret;
+
+    if (qemuDomainObjEnterMonitorAsync(driver, vm, job) < 0)
+        return -1;
+
+    ret = qemuMonitorGetMigrationCapability(
+                priv->mon,
+                QEMU_MONITOR_MIGRATION_CAPS_POSTCOPY);
+
+    if (ret < 0) {
+        goto cleanup;
+    } else if (ret == 0) {
+        if (job == QEMU_ASYNC_JOB_MIGRATION_IN) {
+            virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
+                           _("Post-copy migration is not supported by "
+                             "target QEMU binary"));
+        } else {
+            virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
+                           _("Post-copy migration is not supported by "
+                             "source QEMU binary"));
+        }
+        ret = -1;
+        goto cleanup;
+    }
+
+    ret = qemuMonitorSetMigrationCapability(
+                priv->mon,
+                QEMU_MONITOR_MIGRATION_CAPS_POSTCOPY);
+
+ cleanup:
+    qemuDomainObjExitMonitor(driver, vm);
+    return ret;
+}
+static int
 qemuMigrationSetCompression(virQEMUDriverPtr driver,
                             virDomainObjPtr vm,
                             qemuDomainAsyncJob job)
@@ -3580,6 +3619,10 @@ qemuMigrationRun(virQEMUDriverPtr driver,
     if (flags & VIR_MIGRATE_RDMA_PIN_ALL &&
         qemuMigrationSetPinAll(driver, vm,
                                QEMU_ASYNC_JOB_MIGRATION_OUT) < 0)
+
+    if (flags & VIR_MIGRATE_POSTCOPY &&
+        qemuMigrationSetPostCopy(driver, vm,
+                                 QEMU_ASYNC_JOB_MIGRATION_OUT) < 0)
         goto cleanup;
 
     if (qemuDomainObjEnterMonitorAsync(driver, vm,
diff --git a/src/qemu/qemu_migration.h b/src/qemu/qemu_migration.h
index e7a90c3..349c9c4 100644
--- a/src/qemu/qemu_migration.h
+++ b/src/qemu/qemu_migration.h
@@ -41,7 +41,8 @@
      VIR_MIGRATE_COMPRESSED |                   \
      VIR_MIGRATE_ABORT_ON_ERROR |               \
      VIR_MIGRATE_AUTO_CONVERGE |                \
-     VIR_MIGRATE_RDMA_PIN_ALL)
+     VIR_MIGRATE_RDMA_PIN_ALL |                 \
+     VIR_MIGRATE_POSTCOPY)
 
 /* All supported migration parameters and their types. */
 # define QEMU_MIGRATION_PARAMETERS                              \
-- 
1.9.1

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