Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20210407b' into staging

V2 migration+virtiofs fixes pull 2021-04-07

A seg fix in virtiofsd, a bunch of fixes for background snapshots, and
a migration test fix.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

v2
  Fix for !linux build

# gpg: Signature made Wed 07 Apr 2021 18:53:13 BST
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-migration-20210407b:
  tests/migration: fix parameter of auto-converge migration
  migration: Rename 'bs' to 'block' in background snapshot code
  migration: Pre-fault memory before starting background snasphot
  migration: Inhibit virtio-balloon for the duration of background snapshot
  migration: Fix missing qemu_fflush() on buffer file in bg_migration_thread
  virtiofsd: Fix security.capability comparison

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

1 files changed, 23 insertions, 1 deletions

diff --git a/migration/migration.c b/migration/migration.c
index ca8b97baa5..8ca034136b 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1976,6 +1976,14 @@ bool migration_in_incoming_postcopy(void)
     return ps >= POSTCOPY_INCOMING_DISCARD && ps < POSTCOPY_INCOMING_END;
 }
 
+bool migration_in_bg_snapshot(void)
+{
+    MigrationState *s = migrate_get_current();
+
+    return migrate_background_snapshot() &&
+            migration_is_setup_or_active(s->state);
+}
+
 bool migration_is_idle(void)
 {
     MigrationState *s = current_migration;
@@ -3812,13 +3820,21 @@ static void *bg_migration_thread(void *opaque)
      * with vCPUs running and, finally, write stashed non-RAM part of
      * the vmstate from the buffer to the migration stream.
      */
-    s->bioc = qio_channel_buffer_new(128 * 1024);
+    s->bioc = qio_channel_buffer_new(512 * 1024);
     qio_channel_set_name(QIO_CHANNEL(s->bioc), "vmstate-buffer");
     fb = qemu_fopen_channel_output(QIO_CHANNEL(s->bioc));
     object_unref(OBJECT(s->bioc));
 
     update_iteration_initial_status(s);
 
+    /*
+     * Prepare for tracking memory writes with UFFD-WP - populate
+     * RAM pages before protecting.
+     */
+#ifdef __linux__
+    ram_write_tracking_prepare();
+#endif
+
     qemu_savevm_state_header(s->to_dst_file);
     qemu_savevm_state_setup(s->to_dst_file);
 
@@ -3866,6 +3882,12 @@ static void *bg_migration_thread(void *opaque)
     if (qemu_savevm_state_complete_precopy_non_iterable(fb, false, false)) {
         goto fail;
     }
+    /*
+     * Since we are going to get non-iterable state data directly
+     * from s->bioc->data, explicit flush is needed here.
+     */
+    qemu_fflush(fb);
+
     /* Now initialize UFFD context and start tracking RAM writes */
     if (ram_write_tracking_start()) {
         goto fail;