[PATCH v2 2/3] qemu: Add support for parallel migration

[Jiri Denemark <jdenemar@xxxxxxxxxx>]

The VIR_MIGRATE_PARALLEL flag is implemented using QEMU's multifd
migration capability and the corresponding multifd-channels migration
parameter.

Signed-off-by: Jiri Denemark <jdenemar@xxxxxxxxxx>
---

Notes:
    QEMU still uses the x- prefix for multifd capability and multifd-channels,
    but Juan already sent a series of patches to make multifd migration fully
    supported by dropping the experimental prefix.

 src/qemu/qemu_migration.c        |  9 ++++++---
 src/qemu/qemu_migration.h        |  5 ++++-
 src/qemu/qemu_migration_params.c | 18 ++++++++++++++++++
 src/qemu/qemu_migration_params.h |  2 ++
 4 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 3107a279dd..22f31680c9 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -3822,10 +3822,13 @@ qemuMigrationSrcPerformNative(virQEMUDriverPtr driver,
         }
     }
 
-    if (STRNEQ(uribits->scheme, "rdma"))
-        spec.destType = MIGRATION_DEST_CONNECT_HOST;
-    else
+    /* RDMA and multi-fd migration requires QEMU to connect to the destination
+     * itself.
+     */
+    if (STREQ(uribits->scheme, "rdma") || (flags & VIR_MIGRATE_PARALLEL))
         spec.destType = MIGRATION_DEST_HOST;
+    else
+        spec.destType = MIGRATION_DEST_CONNECT_HOST;
     spec.dest.host.protocol = uribits->scheme;
     spec.dest.host.name = uribits->server;
     spec.dest.host.port = uribits->port;
diff --git a/src/qemu/qemu_migration.h b/src/qemu/qemu_migration.h
index ca73d3e467..fea5000a4d 100644
--- a/src/qemu/qemu_migration.h
+++ b/src/qemu/qemu_migration.h
@@ -57,7 +57,9 @@
      VIR_MIGRATE_AUTO_CONVERGE | \
      VIR_MIGRATE_RDMA_PIN_ALL | \
      VIR_MIGRATE_POSTCOPY | \
-     VIR_MIGRATE_TLS)
+     VIR_MIGRATE_TLS | \
+     VIR_MIGRATE_PARALLEL | \
+     0)
 
 /* All supported migration parameters and their types. */
 # define QEMU_MIGRATION_PARAMETERS \
@@ -80,6 +82,7 @@
     VIR_MIGRATE_PARAM_AUTO_CONVERGE_INITIAL,        VIR_TYPED_PARAM_INT, \
     VIR_MIGRATE_PARAM_AUTO_CONVERGE_INCREMENT,      VIR_TYPED_PARAM_INT, \
     VIR_MIGRATE_PARAM_BANDWIDTH_POSTCOPY, VIR_TYPED_PARAM_ULLONG, \
+    VIR_MIGRATE_PARAM_PARALLEL_CONNECTIONS, VIR_TYPED_PARAM_INT, \
     NULL
 
 
diff --git a/src/qemu/qemu_migration_params.c b/src/qemu/qemu_migration_params.c
index 28f2c75ea1..82416667a6 100644
--- a/src/qemu/qemu_migration_params.c
+++ b/src/qemu/qemu_migration_params.c
@@ -86,6 +86,7 @@ VIR_ENUM_IMPL(qemuMigrationCapability, QEMU_MIGRATION_CAP_LAST,
               "compress",
               "pause-before-switchover",
               "late-block-activate",
+              "multifd",
 );
 
 
@@ -103,6 +104,7 @@ VIR_ENUM_IMPL(qemuMigrationParam, QEMU_MIGRATION_PARAM_LAST,
               "block-incremental",
               "xbzrle-cache-size",
               "max-postcopy-bandwidth",
+              "multifd-channels",
 );
 
 typedef struct _qemuMigrationParamsAlwaysOnItem qemuMigrationParamsAlwaysOnItem;
@@ -151,6 +153,10 @@ static const qemuMigrationParamsFlagMapItem qemuMigrationParamsFlagMap[] = {
     {VIR_MIGRATE_POSTCOPY,
      QEMU_MIGRATION_CAP_POSTCOPY,
      QEMU_MIGRATION_SOURCE | QEMU_MIGRATION_DESTINATION},
+
+    {VIR_MIGRATE_PARALLEL,
+     QEMU_MIGRATION_CAP_MULTIFD,
+     QEMU_MIGRATION_SOURCE | QEMU_MIGRATION_DESTINATION},
 };
 
 /* Translation from VIR_MIGRATE_PARAM_* typed parameters to
@@ -184,6 +190,10 @@ static const qemuMigrationParamsTPMapItem qemuMigrationParamsTPMap[] = {
      .unit = 1024 * 1024, /* MiB/s */
      .param = QEMU_MIGRATION_PARAM_MAX_POSTCOPY_BANDWIDTH,
      .party = QEMU_MIGRATION_SOURCE | QEMU_MIGRATION_DESTINATION},
+
+    {.typedParam = VIR_MIGRATE_PARAM_PARALLEL_CONNECTIONS,
+     .param = QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS,
+     .party = QEMU_MIGRATION_SOURCE | QEMU_MIGRATION_DESTINATION},
 };
 
 static const qemuMigrationParamType qemuMigrationParamTypes[] = {
@@ -199,6 +209,7 @@ static const qemuMigrationParamType qemuMigrationParamTypes[] = {
     [QEMU_MIGRATION_PARAM_BLOCK_INCREMENTAL] = QEMU_MIGRATION_PARAM_TYPE_BOOL,
     [QEMU_MIGRATION_PARAM_XBZRLE_CACHE_SIZE] = QEMU_MIGRATION_PARAM_TYPE_ULL,
     [QEMU_MIGRATION_PARAM_MAX_POSTCOPY_BANDWIDTH] = QEMU_MIGRATION_PARAM_TYPE_ULL,
+    [QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS] = QEMU_MIGRATION_PARAM_TYPE_INT,
 };
 verify(ARRAY_CARDINALITY(qemuMigrationParamTypes) == QEMU_MIGRATION_PARAM_LAST);
 
@@ -535,6 +546,13 @@ qemuMigrationParamsFromFlags(virTypedParameterPtr params,
         goto error;
     }
 
+    if (migParams->params[QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS].set &&
+        !(flags & VIR_MIGRATE_PARALLEL)) {
+        virReportError(VIR_ERR_INVALID_ARG, "%s",
+                       _("Turn parallel migration on to tune it"));
+        goto error;
+    }
+
     if (qemuMigrationParamsSetCompression(params, nparams, flags, migParams) < 0)
         goto error;
 
diff --git a/src/qemu/qemu_migration_params.h b/src/qemu/qemu_migration_params.h
index 233ebe772b..0515339d91 100644
--- a/src/qemu/qemu_migration_params.h
+++ b/src/qemu/qemu_migration_params.h
@@ -38,6 +38,7 @@ typedef enum {
     QEMU_MIGRATION_CAP_COMPRESS,
     QEMU_MIGRATION_CAP_PAUSE_BEFORE_SWITCHOVER,
     QEMU_MIGRATION_CAP_LATE_BLOCK_ACTIVATE,
+    QEMU_MIGRATION_CAP_MULTIFD,
 
     QEMU_MIGRATION_CAP_LAST
 } qemuMigrationCapability;
@@ -56,6 +57,7 @@ typedef enum {
     QEMU_MIGRATION_PARAM_BLOCK_INCREMENTAL,
     QEMU_MIGRATION_PARAM_XBZRLE_CACHE_SIZE,
     QEMU_MIGRATION_PARAM_MAX_POSTCOPY_BANDWIDTH,
+    QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS,
 
     QEMU_MIGRATION_PARAM_LAST
 } qemuMigrationParam;
-- 
2.20.1