Merge tag 'migration-20230206-pull-request' of https://gitlab.com/juan.quintela/qemu into staging

Migration Pull request

In this try
- rebase to latest upstream
- same than previous patch
- fix compilation on non linux (userfaultfd.h) (me)
- query-migrationthreads (jiang)
- fix race on reading MultiFDPages_t.block (zhenzhong)
- fix flush of zero copy page send reuest  (zhenzhong)

Please apply.

Previous try:
It includes:
- David Hildenbrand fixes for virtio-men
- David Gilbert canary to detect problems
- Fix for rdma return values (Fiona)
- Peter Xu uffd_open fixes
- Peter Xu show right downtime for postcopy
- manish.mishra msg fix fixes
- my vfio changes.

Please apply.

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# gpg:                 aka "Juan Quintela <quintela@trasno.org>" [full]
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03  4B82 F487 EF18 5872 D723

* tag 'migration-20230206-pull-request' of https://gitlab.com/juan.quintela/qemu: (30 commits)
  migration: save/delete migration thread info
  migration: Introduce interface query-migrationthreads
  multifd: Fix flush of zero copy page send request
  multifd: Fix a race on reading MultiFDPages_t.block
  migration: check magic value for deciding the mapping of channels
  io: Add support for MSG_PEEK for socket channel
  migration/dirtyrate: Show sample pages only in page-sampling mode
  migration: Perform vmsd structure check during tests
  migration: Add canary to VMSTATE_END_OF_LIST
  migration/rdma: fix return value for qio_channel_rdma_{readv,writev}
  migration: Show downtime during postcopy phase
  virtio-mem: Proper support for preallocation with migration
  virtio-mem: Migrate immutable properties early
  virtio-mem: Fail if a memory backend with "prealloc=on" is specified
  migration/ram: Factor out check for advised postcopy
  migration/vmstate: Introduce VMSTATE_WITH_TMP_TEST() and VMSTATE_BITMAP_TEST()
  migration/savevm: Allow immutable device state to be migrated early (i.e., before RAM)
  migration/savevm: Prepare vmdesc json writer in qemu_savevm_state_setup()
  migration/savevm: Move more savevm handling into vmstate_save()
  migration/ram: Optimize ram_write_tracking_start() for RamDiscardManager
  ...

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

2 files changed, 13 insertions, 11 deletions

diff --git a/docs/devel/migration.rst b/docs/devel/migration.rst
index 3e9656d..6f65c23 100644
--- a/docs/devel/migration.rst
+++ b/docs/devel/migration.rst
@@ -482,15 +482,17 @@ An iterative device must provide:
   - A ``load_setup`` function that initialises the data structures on the
     destination.
 
-  - A ``save_live_pending`` function that is called repeatedly and must
-    indicate how much more data the iterative data must save.  The core
-    migration code will use this to determine when to pause the CPUs
-    and complete the migration.
-
-  - A ``save_live_iterate`` function (called after ``save_live_pending``
-    when there is significant data still to be sent).  It should send
-    a chunk of data until the point that stream bandwidth limits tell it
-    to stop.  Each call generates one section.
+  - A ``state_pending_exact`` function that indicates how much more
+    data we must save.  The core migration code will use this to
+    determine when to pause the CPUs and complete the migration.
+
+  - A ``state_pending_estimate`` function that indicates how much more
+    data we must save.  When the estimated amount is smaller than the
+    threshold, we call ``state_pending_exact``.
+
+  - A ``save_live_iterate`` function should send a chunk of data until
+    the point that stream bandwidth limits tell it to stop.  Each call
+    generates one section.
 
   - A ``save_live_complete_precopy`` function that must transmit the
     last section for the device containing any remaining data.
diff --git a/docs/devel/vfio-migration.rst b/docs/devel/vfio-migration.rst
index 9ff6163..673057c 100644
--- a/docs/devel/vfio-migration.rst
+++ b/docs/devel/vfio-migration.rst
@@ -28,7 +28,7 @@ VFIO implements the device hooks for the iterative approach as follows:
 * A ``load_setup`` function that sets up the migration region on the
   destination and sets _RESUMING flag in the VFIO device state.
 
-* A ``save_live_pending`` function that reads pending_bytes from the vendor
+* A ``state_pending_exact`` function that reads pending_bytes from the vendor
   driver, which indicates the amount of data that the vendor driver has yet to
   save for the VFIO device.
 
@@ -114,7 +114,7 @@ Live migration save path
                     (RUNNING, _SETUP, _RUNNING|_SAVING)
                                   |
                     (RUNNING, _ACTIVE, _RUNNING|_SAVING)
-             If device is active, get pending_bytes by .save_live_pending()
+             If device is active, get pending_bytes by .state_pending_exact()
           If total pending_bytes >= threshold_size, call .save_live_iterate()
                   Data of VFIO device for pre-copy phase is copied
         Iterate till total pending bytes converge and are less than threshold