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[Qemu-devel] [RFC PATCH v12 00/21] Deterministic replay core

From: Pavel Dovgalyuk
Subject: [Qemu-devel] [RFC PATCH v12 00/21] Deterministic replay core
Date: Tue, 05 May 2015 13:17:35 +0300
User-agent: StGit/0.16

This set of patches is related to the reverse execution and deterministic 
replay of qemu execution. This implementation of deterministic replay can 
be used for deterministic debugging of guest code through gdb remote

Core set of patches does not include support for reverse debugging commands
of gdb, block devices' operations, USB replay support.

These patches include only core function of the replay,
excluding the support for replaying serial, audio, network, and USB devices'
operations. Reverse debugging and monitor commands were also excluded to
be submitted later as separate patches.

Execution recording writes non-deterministic events log, which can be later 
used for replaying the execution anywhere and for unlimited number of times. 
It also supports checkpointing for faster rewinding during reverse debugging. 
Execution replaying reads the log and replays all non-deterministic events 
including external input, hardware clocks, and interrupts.

Full version of deterministic replay has the following features:
 * Deterministically replays whole system execution and all contents of the 
   state of the hadrware devices, clocks, and screen of the VM.
 * Writes execution log into the file for latter replaying for multiple times 
   on different machines.
 * Supports i386, x86_64, and ARM hardware platforms.
 * Performs deterministic replay of all operations with keyboard and mouse
   input devices.
 * Supports auto-checkpointing for convenient reverse debugging.

Usage of the record/replay core:
 * First, record the execution, by adding the following string to the command 
   '-icount shift=7,rr=record,rrfile=replay.bin -net none'. 
   Block devices' images are not actually changed in the recording mode, 
   because all of the changes are written to the temporary overlay file.
 * Then you can replay it for the multiple times by using another command
   line option: '-icount shift=7,rr=replay,rrfile=replay.bin -net none'
 * '-net none' option should also be specified if network replay patches
   are not applied.
 * Do not add any disk images to VM, because they are not supported by
   the core patches.

Paper with short description of deterministic replay implementation:

Modifications of qemu include:
 * wrappers for clock and time functions to save their return values in the log
 * saving different asynchronous events (e.g. system shutdown) into the log
 * synchronization of the threads from thread pool
 * recording/replaying user input (mouse and keyboard)
 * adding internal events for cpu and io synchronization

v12 changes:
 * Removed block patches from the core patches set.

v11 changes:
 * Fixed instructions event processing.
 * Added some mutex protection calls for replay.
 * Fixed replaying read operations for qcow2.
 * Fixed rtc reads on initializations stage.
 * Eliminated some warnings in replay module.
 * Fixed misprints in documentation for replay (as suggested by Eric Blake)

v10 changes:
 * Fixed queue processing for bottom halves (as suggested by Paolo Bonzini)
 * Rewritten several replay functions (as suggested by Paolo Bonzini)
 * Some minor fixes.

v9 changes:
 * Replaced fwrite/fread with putc/getc (as suggested by Paolo Bonzini)
 * Stopping virtual machine in case of replay file end (as suggested by Paolo 
 * Removed one of the replay mutexes (as suggested by Paolo Bonzini)
 * Fixed RCU queue for bottom halves (as suggested by Paolo Bonzini)
 * Updated command line options' names (as suggested by Paolo Bonzini)
 * Added design document for record/replay (as suggested by Paolo Bonzini)
 * Simplified checkpoints for the timers
 * Added cloning InputEvent objects for replay (as suggested by Paolo Bonzini)
 * Added replay blockers instead of checking the command line (as suggested by 
Paolo Bonzini)
 * Some functions renaming and extracting.

v8 changes:
 * Simplified processing of the shutdown event (as suggested by Paolo Bonzini)
 * Replaced stack of bottom halves in AIO context with QSIMPLEQ (as suggested 
by Paolo Bonzini)
 * Moved replay_submode out of the series (as suggested by Paolo Bonzini)
 * Moved suffix option out of the series
 * Converted some of the defines into enums (as suggested by Paolo Bonzini)
 * Encapsulated save_tm/read_tm calls into the single function (as suggested by 
Paolo Bonzini)
 * Moved record/replay options to icount group (as suggested by Paolo Bonzini)
 * Updated mutex protection for the events queue (as suggested by Paolo Bonzini)
 * Added mutex to protect replay log file (as suggested by Paolo Bonzini)
 * Minor cleanups

v7 changes:
 * Removed patches that were applied to upstream.

v6 changes:
 * Fixed replay stub return value (as suggested by Eric Blake)
 * Fixed icount warping.
 * Virtual rt clock now uses cpu_get_clock() (as suggested by Paolo Bonzini)
 * Replated get_clock_realtime and get_clock calls with qemu clock requests (as 
suggested by Paolo Bonzini)
 * Modified can_do_io logic to allow requesting icount from cpu_exec function 
(as suggested by Paolo Bonzini)
 * Removed applied patches.

v5 changes:
 * Minor changes.
 * Used fixed-width integer types for read/write functions (as suggested by 
Alex Bennee)
 * Moved savevm-related code out of the core.
 * Added new traced clock for deterministic virtual clock warping (as suggested 
by Paolo Bonzini)
 * Fixed exception_index reset for user mode (as suggested by Paolo Bonzini)
 * Adopted Paolo's icount patches
 * Fixed hardware interrupts replaying

v4 changes:
 * Updated block drivers to support new bdrv_open interface.
 * Moved migration patches into separate series (as suggested by Paolo Bonzini)
 * Fixed a bug in replay_break operation.
 * Fixed rtl8139 migration for replay.
 * Fixed 'period' parameter processing for record mode.
 * Fixed bug in 'reverse-stepi' implementation.
 * Fixed replay without making any snapshots (even the starting one).
 * Moved core replay patches into the separate series.
 * Fixed reverse step and reverse continue support.
 * Fixed several bugs in icount subsystem.
 * Reusing native qemu icount for replay instructions counting.
 * Separated core patches into their own series.

v3 changes:
 * Fixed bug with replay of the aio write operations.
 * Added virtual clock based on replay icount.
 * Removed duplicated saving of interrupt_request CPU field.
 * Fixed some coding style issues.
 * Renamed QMP commands for controlling reverse execution (as suggested by Eric 
 * Replay mode and submode implemented as QAPI enumerations (as suggested by 
Eric Blake)
 * Added description and example for replay-info command (as suggested by Eric 
 * Added information about the current breakpoint to the output of replay-info 
(as suggested by Eric Blake)
 * Updated version id for HPET vmstate (as suggested by Paolo Bonzini)
 * Removed static fields from parallel vmstate (as suggested by Paolo Bonzini)
 * New vmstate fields for mc146818rtc, pckbd, kvmapic, serial, fdc, rtl8139 
moved to subsection (as suggested by Paolo Bonzini)
 * Disabled textmode cursor blinking, when virtual machine is stopped (as 
suggested by Paolo Bonzini)
 * Extracted saving of exception_index to separate patch (as suggested by Paolo 

v2 changes:
 * Patches are split to be reviewable and bisectable (as suggested by Kirill 
 * Added QMP versions of replay commands (as suggested by Eric Blake)
 * Removed some optional features of replay to make patches cleaner
 * Minor changes and code cleanup were made


Pavel Dovgalyuk (20):
      i386: partial revert of interrupt poll fix
      replay: global variables and function stubs
      sysemu: system functions for replay
      replay: internal functions for replay log
      replay: introduce mutex to protect the replay log
      replay: introduce icount event
      cpu-exec: allow temporary disabling icount
      cpu: replay instructions sequence
      i386: interrupt poll processing
      replay: interrupts and exceptions
      replay: asynchronous events infrastructure
      replay: recording and replaying clock ticks
      replay: shutdown event
      replay: checkpoints
      aio: replace stack of bottom halves with queue
      typedef: add typedef for QemuOpts
      replay: initialization and deinitialization
      replay: replay blockers for devices
      replay: command line options
      replay: recording of the user input

 Makefile.target           |    1 
 async.c                   |   50 ++++---
 cpu-exec.c                |   59 ++++++--
 cpus.c                    |   48 ++++--
 dma-helpers.c             |    4 -
 docs/replay.txt           |  167 ++++++++++++++++++++++
 exec.c                    |    1 
 hw/bt/hci.c               |    7 +
 hw/timer/arm_timer.c      |    2 
 include/block/aio.h       |   22 +++
 include/exec/exec-all.h   |    2 
 include/qapi/qmp/qerror.h |    3 
 include/qemu/main-loop.h  |    1 
 include/qemu/option.h     |    5 -
 include/qemu/queue.h      |   18 ++
 include/qemu/typedefs.h   |    3 
 include/qom/cpu.h         |   10 +
 include/sysemu/cpus.h     |    1 
 include/ui/input.h        |    2 
 main-loop.c               |   11 +
 qapi-schema.json          |   18 ++
 qemu-options.hx           |    8 +
 qemu-timer.c              |   45 +++++-
 replay/Makefile.objs      |    5 +
 replay/replay-events.c    |  274 ++++++++++++++++++++++++++++++++++++
 replay/replay-input.c     |  159 +++++++++++++++++++++
 replay/replay-internal.c  |  200 ++++++++++++++++++++++++++
 replay/replay-internal.h  |  142 +++++++++++++++++++
 replay/replay-time.c      |   64 ++++++++
 replay/replay.c           |  345 +++++++++++++++++++++++++++++++++++++++++++++
 replay/replay.h           |  119 ++++++++++++++++
 stubs/Makefile.objs       |    1 
 stubs/replay.c            |   37 +++++
 target-i386/cpu.c         |   10 -
 target-i386/seg_helper.c  |    3 
 translate-all.c           |   10 +
 ui/input.c                |   27 ++--
 vl.c                      |   42 +++++
 38 files changed, 1845 insertions(+), 81 deletions(-)
 create mode 100755 docs/replay.txt
 create mode 100755 replay/Makefile.objs
 create mode 100755 replay/replay-events.c
 create mode 100755 replay/replay-input.c
 create mode 100755 replay/replay-internal.c
 create mode 100755 replay/replay-internal.h
 create mode 100755 replay/replay-time.c
 create mode 100755 replay/replay.c
 create mode 100755 replay/replay.h
 create mode 100755 stubs/replay.c

Pavel Dovgalyuk

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