Merge tag 'migration-20250711-pull-request' of https://gitlab.com/farosas/qemu into staging

Migration pull request

- General cleanups around: postcopy, bg-snapshot, migration hooks,
  migration completion and formatting of 'info migrate'.

- Overhaul of postcopy blocktime tracking.

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* tag 'migration-20250711-pull-request' of https://gitlab.com/farosas/qemu: (26 commits)
  migration: Rename save_live_complete_precopy_thread to save_complete_precopy_thread
  migration/postcopy: Add latency distribution report for blocktime
  migration/postcopy: blocktime allows track / report non-vCPU faults
  migration/postcopy: Optimize blocktime fault tracking with hashtable
  migration/postcopy: Cleanup the total blocktime accounting
  migration/postcopy: Cache the tid->vcpu mapping for blocktime
  migration/postcopy: Initialize blocktime context only until listen
  migration/postcopy: Report fault latencies in blocktime
  migration/postcopy: Add blocktime fault counts per-vcpu
  migration/postcopy: Bring blocktime layer to ns level
  migration/postcopy: Drop PostcopyBlocktimeContext.start_time
  migration/postcopy: Make all blocktime vars 64bits
  migration/postcopy: Drop all atomic ops in blocktime feature
  migration/postcopy: Push blocktime start/end into page req mutex
  migration: Add option to set postcopy-blocktime
  migration/postcopy: Avoid clearing dirty bitmap for postcopy too
  migration: Rewrite the migration complete detect logic
  migration/ram: Add tracepoints for ram_save_complete()
  migration/ram: One less indent for ram_find_and_save_block()
  migration: qemu_savevm_complete*() helpers
  ...

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

3 files changed, 27 insertions, 29 deletions

diff --git a/docs/devel/migration/main.rst b/docs/devel/migration/main.rst
index cdd4f4a..6493c1d 100644
--- a/docs/devel/migration/main.rst
+++ b/docs/devel/migration/main.rst
@@ -508,8 +508,8 @@ An iterative device must provide:
     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.
+  - A ``save_complete`` function that must transmit the last section for
+    the device containing any remaining data.
 
   - A ``load_state`` function used to load sections generated by
     any of the save functions that generate sections.
diff --git a/docs/devel/migration/postcopy.rst b/docs/devel/migration/postcopy.rst
index 82e7a84..e319388 100644
--- a/docs/devel/migration/postcopy.rst
+++ b/docs/devel/migration/postcopy.rst
@@ -33,25 +33,6 @@ will now cause the transition from precopy to postcopy.
 It can be issued immediately after migration is started or any
 time later on.  Issuing it after the end of a migration is harmless.
 
-Blocktime is a postcopy live migration metric, intended to show how
-long the vCPU was in state of interruptible sleep due to pagefault.
-That metric is calculated both for all vCPUs as overlapped value, and
-separately for each vCPU. These values are calculated on destination
-side.  To enable postcopy blocktime calculation, enter following
-command on destination monitor:
-
-``migrate_set_capability postcopy-blocktime on``
-
-Postcopy blocktime can be retrieved by query-migrate qmp command.
-postcopy-blocktime value of qmp command will show overlapped blocking
-time for all vCPU, postcopy-vcpu-blocktime will show list of blocking
-time per vCPU.
-
-.. note::
-  During the postcopy phase, the bandwidth limits set using
-  ``migrate_set_parameter`` is ignored (to avoid delaying requested pages that
-  the destination is waiting for).
-
 Postcopy internals
 ==================
 
@@ -312,3 +293,20 @@ explicitly) to be sent in a separate preempt channel, rather than queued in
 the background migration channel.  Anyone who cares about latencies of page
 faults during a postcopy migration should enable this feature.  By default,
 it's not enabled.
+
+Postcopy blocktime statistics
+-----------------------------
+
+Blocktime is a postcopy live migration metric, intended to show how
+long the vCPU was in state of interruptible sleep due to pagefault.
+That metric is calculated both for all vCPUs as overlapped value, and
+separately for each vCPU. These values are calculated on destination
+side.  To enable postcopy blocktime calculation, enter following
+command on destination monitor:
+
+``migrate_set_capability postcopy-blocktime on``
+
+Postcopy blocktime can be retrieved by query-migrate qmp command.
+postcopy-blocktime value of qmp command will show overlapped blocking
+time for all vCPU, postcopy-vcpu-blocktime will show list of blocking
+time per vCPU.
diff --git a/docs/devel/migration/vfio.rst b/docs/devel/migration/vfio.rst
index 673e354..2d8e5ca 100644
--- a/docs/devel/migration/vfio.rst
+++ b/docs/devel/migration/vfio.rst
@@ -75,12 +75,12 @@ VFIO implements the device hooks for the iterative approach as follows:
   in the non-multifd mode.
   In the multifd mode it just emits either a dummy EOS marker.
 
-* A ``save_live_complete_precopy`` function that sets the VFIO device in
-  _STOP_COPY state and iteratively copies the data for the VFIO device until
-  the vendor driver indicates that no data remains.
-  In the multifd mode it just emits a dummy EOS marker.
+* A ``save_complete`` function that sets the VFIO device in _STOP_COPY
+  state and iteratively copies the data for the VFIO device until the
+  vendor driver indicates that no data remains.  In the multifd mode it
+  just emits a dummy EOS marker.
 
-* A ``save_live_complete_precopy_thread`` function that in the multifd mode
+* A ``save_complete_precopy_thread`` function that in the multifd mode
   provides thread handler performing multifd device state transfer.
   It sets the VFIO device to _STOP_COPY state, iteratively reads the data
   from the VFIO device and queues it for multifd transmission until the vendor
@@ -195,12 +195,12 @@ Live migration save path
                                       |
                 Then the VFIO device is put in _STOP_COPY state
                      (FINISH_MIGRATE, _ACTIVE, _STOP_COPY)
-         .save_live_complete_precopy() is called for each active device
+               .save_complete() is called for each active device
               For the VFIO device: in the non-multifd mode iterate in
-                        .save_live_complete_precopy() until
+                             .save_complete() until
                                pending data is 0
 	          In the multifd mode this iteration is done in
-	          .save_live_complete_precopy_thread() instead.
+	          .save_complete_precopy_thread() instead.
                                       |
                      (POSTMIGRATE, _COMPLETED, _STOP_COPY)
             Migraton thread schedules cleanup bottom half and exits