From f15935ea3b510bf0633dc2219a132412a7a8e96c Mon Sep 17 00:00:00 2001
From: Lin Ma <lma@suse.com>
Date: Thu, 16 Apr 2020 12:44:51 +0800
Subject: [PATCH 3/8] qemu: fix hang in p2p + xbzrle compression + parallel
 migration

When we do parallel migration, The multifd-channels migration parameter
needs to be set on the destination side as well before incoming migration
URI, unless we accept the default number of connections(2).

Usually, This can be correctly handled by libvirtd. But in this case if
we use p2p + xbzrle compression without parameter '--comp-xbzrle-cache',
qemuMigrationParamsDump returns too early, The corresponding migration
parameter will not be set on the destination side, It results QEMU hangs.

Reproducer:
virsh migrate --live --p2p --comp-methods xbzrle \
--parallel --parallel-connections 3 GUEST qemu+ssh://dsthost/system

or

virsh migrate --live --p2p --compressed \
--parallel --parallel-connections 3 GUEST qemu+ssh://dsthost/system

Signed-off-by: Lin Ma <lma@suse.com>
Message-Id: <20200416044451.21134-1-lma@suse.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
(cherry-picked from commit 93b15ba0)
Signed-off-by: AlexChen <alex.chen@huawei.com>
---
 src/qemu/qemu_migration_params.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/qemu/qemu_migration_params.c b/src/qemu/qemu_migration_params.c
index dd5e2ce1b6..810199370f 100644
--- a/src/qemu/qemu_migration_params.c
+++ b/src/qemu/qemu_migration_params.c
@@ -630,7 +630,6 @@ qemuMigrationParamsDump(qemuMigrationParamsPtr migParams,
     if (migParams->compMethods == 1ULL << QEMU_MIGRATION_COMPRESS_XBZRLE &&
         !migParams->params[QEMU_MIGRATION_PARAM_XBZRLE_CACHE_SIZE].set) {
         *flags |= VIR_MIGRATE_COMPRESSED;
-        return 0;
     }
 
     for (i = 0; i < QEMU_MIGRATION_COMPRESS_LAST; ++i) {
-- 
2.23.0