Merge tag 'migration-20240407-pull-request' of https://gitlab.com/peterx/qemu into staging
Migration pull for 9.0-rc3
- Wei/Lei's fix on a rare postcopy race that can hang the channel (since 8.0)
- Avihai's fix on maintainers file, points to the right doc links
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# gpg: Good signature from "Peter Xu <xzpeter@gmail.com>" [marginal]
# gpg: aka "Peter Xu <peterx@redhat.com>" [marginal]
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* tag 'migration-20240407-pull-request' of https://gitlab.com/peterx/qemu:
MAINTAINERS: Adjust migration documentation files
migration/postcopy: ensure preempt channel is ready before loading states
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index e71183e..d3fc2a0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2170,7 +2170,7 @@
F: hw/vfio/*
F: include/hw/vfio/
F: docs/igd-assign.txt
-F: docs/devel/vfio-migration.rst
+F: docs/devel/migration/vfio.rst
vfio-ccw
M: Eric Farman <farman@linux.ibm.com>
@@ -2231,6 +2231,7 @@
F: net/vhost-user.c
F: include/hw/virtio/
F: docs/devel/virtio*
+F: docs/devel/migration/virtio.rst
virtio-balloon
M: Michael S. Tsirkin <mst@redhat.com>
@@ -3422,7 +3423,7 @@
F: scripts/vmstate-static-checker.py
F: tests/vmstate-static-checker-data/
F: tests/qtest/migration-test.c
-F: docs/devel/migration.rst
+F: docs/devel/migration/
F: qapi/migration.json
F: tests/migration/
F: util/userfaultfd.c
@@ -3442,6 +3443,7 @@
F: migration/dirtyrate.c
F: migration/dirtyrate.h
F: include/sysemu/dirtyrate.h
+F: docs/devel/migration/dirty-limit.rst
Detached LUKS header
M: Hyman Huang <yong.huang@smartx.com>
diff --git a/migration/savevm.c b/migration/savevm.c
index 388d7af..e7c1215 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2342,6 +2342,27 @@
QEMUFile *packf = qemu_file_new_input(QIO_CHANNEL(bioc));
+ /*
+ * Before loading the guest states, ensure that the preempt channel has
+ * been ready to use, as some of the states (e.g. via virtio_load) might
+ * trigger page faults that will be handled through the preempt channel.
+ * So yield to the main thread in the case that the channel create event
+ * hasn't been dispatched.
+ *
+ * TODO: if we can move migration loadvm out of main thread, then we
+ * won't block main thread from polling the accept() fds. We can drop
+ * this as a whole when that is done.
+ */
+ do {
+ if (!migrate_postcopy_preempt() || !qemu_in_coroutine() ||
+ mis->postcopy_qemufile_dst) {
+ break;
+ }
+
+ aio_co_schedule(qemu_get_current_aio_context(), qemu_coroutine_self());
+ qemu_coroutine_yield();
+ } while (1);
+
ret = qemu_loadvm_state_main(packf, mis);
trace_loadvm_handle_cmd_packaged_main(ret);
qemu_fclose(packf);
