Merge tag 'migration-20230412-pull-request' of https://gitlab.com/juan.quintela/qemu into staging

Migration Pull request for 8.0

Last patches found:
- peter xu preempt channel fixes.
  needed for backward compatibility with old machine types.
- lukas fix to get compress working again.

- fix ram on s390x.  Get back to the old code, even when it shouldn't
  be needed, but as it fails on s390x, just revert.

Later, Juan.

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# gpg: Signature made Wed 12 Apr 2023 22:09:24 BST
# gpg:                using RSA key 1899FF8EDEBF58CCEE034B82F487EF185872D723
# gpg: Good signature from "Juan Quintela <quintela@redhat.com>" [full]
# gpg:                 aka "Juan Quintela <quintela@trasno.org>" [full]
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03  4B82 F487 EF18 5872 D723

* tag 'migration-20230412-pull-request' of https://gitlab.com/juan.quintela/qemu:
  migration: fix ram_state_pending_exact()
  migration/ram.c: Fix migration with compress enabled
  migration: Recover behavior of preempt channel creation for pre-7.2
  migration: Fix potential race on postcopy_qemufile_src
  io: tls: Inherit QIO_CHANNEL_FEATURE_SHUTDOWN on server side

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 17 insertions, 2 deletions

diff --git a/migration/migration.c b/migration/migration.c
index ae2025d9d8..bda4789193 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3464,8 +3464,12 @@ static void migration_completion(MigrationState *s)
         qemu_savevm_state_complete_postcopy(s->to_dst_file);
         qemu_mutex_unlock_iothread();
 
-        /* Shutdown the postcopy fast path thread */
-        if (migrate_postcopy_preempt()) {
+        /*
+         * Shutdown the postcopy fast path thread.  This is only needed
+         * when dest QEMU binary is old (7.1/7.2).  QEMU 8.0+ doesn't need
+         * this.
+         */
+        if (migrate_postcopy_preempt() && s->preempt_pre_7_2) {
             postcopy_preempt_shutdown_file(s);
         }
 
@@ -4384,6 +4388,15 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
         }
     }
 
+    /*
+     * This needs to be done before resuming a postcopy.  Note: for newer
+     * QEMUs we will delay the channel creation until postcopy_start(), to
+     * avoid disorder of channel creations.
+     */
+    if (migrate_postcopy_preempt() && s->preempt_pre_7_2) {
+        postcopy_preempt_setup(s);
+    }
+
     if (resume) {
         /* Wakeup the main migration thread to do the recovery */
         migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_PAUSED,
@@ -4443,6 +4456,8 @@ static Property migration_properties[] = {
                       decompress_error_check, true),
     DEFINE_PROP_UINT8("x-clear-bitmap-shift", MigrationState,
                       clear_bitmap_shift, CLEAR_BITMAP_SHIFT_DEFAULT),
+    DEFINE_PROP_BOOL("x-preempt-pre-7-2", MigrationState,
+                     preempt_pre_7_2, false),
 
     /* Migration parameters */
     DEFINE_PROP_UINT8("x-compress-level", MigrationState,