The migration tests have support for being passed two QEMU binaries to
test migration compatibility.

Add a CI job that builds the lastest release of QEMU and another job
that uses that version plus an already present build of the current
version and run the migration tests with the two, both as source and
destination. I.e.:

 old QEMU (n-1) -> current QEMU (development tree)
 current QEMU (development tree) -> old QEMU (n-1)

The purpose of this CI job is to ensure the code we're about to merge
will not cause a migration compatibility problem when migrating the
next release (which will contain that code) to/from the previous
release.

I'm leaving the jobs as manual for now because using an older QEMU in
tests could hit bugs that were already fixed in the current
development tree and we need to handle those case-by-case.

Note: for user forks, the version tags need to be pushed to gitlab
otherwise it won't be able to checkout a different version.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 .gitlab-ci.d/buildtest.yml | 53 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/.gitlab-ci.d/buildtest.yml b/.gitlab-ci.d/buildtest.yml
index 91663946de..81163a3f6a 100644
--- a/.gitlab-ci.d/buildtest.yml
+++ b/.gitlab-ci.d/buildtest.yml
@@ -167,6 +167,59 @@ build-system-centos:
       x86_64-softmmu rx-softmmu sh4-softmmu nios2-softmmu
     MAKE_CHECK_ARGS: check-build
 
+build-previous-qemu:
+  extends: .native_build_job_template
+  artifacts:
+    when: on_success
+    expire_in: 2 days
+    paths:
+      - build-previous
+    exclude:
+      - build-previous/**/*.p
+      - build-previous/**/*.a.p
+      - build-previous/**/*.fa.p
+      - build-previous/**/*.c.o
+      - build-previous/**/*.c.o.d
+      - build-previous/**/*.fa
+  needs:
+    job: amd64-opensuse-leap-container
+  variables:
+    QEMU_JOB_OPTIONAL: 1
+    IMAGE: opensuse-leap
+    TARGETS: x86_64-softmmu aarch64-softmmu
+  before_script:
+    - export QEMU_PREV_VERSION="$(sed 's/\([0-9.]*\)\.[0-9]*/v\1.0/' VERSION)"
+    - git checkout $QEMU_PREV_VERSION
+  after_script:
+    - mv build build-previous
+
+.migration-compat-common:
+  extends: .common_test_job_template
+  needs:
+    - job: build-previous-qemu
+    - job: build-system-opensuse
+  allow_failure: true
+  variables:
+    QEMU_JOB_OPTIONAL: 1
+    IMAGE: opensuse-leap
+    MAKE_CHECK_ARGS: check-build
+  script:
+    - cd build
+    - QTEST_QEMU_BINARY_SRC=../build-previous/qemu-system-${TARGET}
+          QTEST_QEMU_BINARY=./qemu-system-${TARGET} ./tests/qtest/migration-test
+    - QTEST_QEMU_BINARY_DST=../build-previous/qemu-system-${TARGET}
+          QTEST_QEMU_BINARY=./qemu-system-${TARGET} ./tests/qtest/migration-test
+
+migration-compat-aarch64:
+  extends: .migration-compat-common
+  variables:
+    TARGET: aarch64
+
+migration-compat-x86_64:
+  extends: .migration-compat-common
+  variables:
+    TARGET: x86_64
+
 check-system-centos:
   extends: .native_test_job_template
   needs:
-- 
2.35.3