[RFC,v4,0/4] QEMU cpus.c refactoring

Motivation and higher level steps:

https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg04628.html

v3 -> v4:

* overall: added copyright headers to all files that were missing them
  (used copyright and license of the module the stuff was extracted from).
  For the new interface files, added SUSE LLC.

* 1/4 (move softmmu only files from root):

  MAINTAINERS: moved softmmu/cpus.c to its final location (from patch 2)

* 2/4 (cpu-throttle):

  MAINTAINERS (to patch 1),
  copyright Fabrice Bellard and license from cpus.c

* 3/4 (cpu-timers, icount):

  - MAINTAINERS: add cpu-timers.c and icount.c to Paolo

  - break very long lines (patchew)

  - add copyright SUSE LLC, GPLv2 to cpu-timers.h

  - add copyright Fabrice Bellard and license from cpus.c to timers-state.h
    as it is lifted from cpus.c

  - vl.c: in configure_accelerators bail out if icount_enabled()
    and !tcg_enabled() as qtest does not enable icount anymore.

* 4/4 (accel stuff to accel):

  - add copyright SUSE LLC to files that mostly only consist of the
    new interface. Add whatever copyright was in the accelerator code
    if instead they mostly consist of accelerator code.

  - change a comment to mention the result of the AccelClass experiment

  - moved qtest accelerator into accel/qtest/ , make it like the others.

  - rename xxx-cpus-interface to xxx-cpus (remove "interface" from names)

  - rename accel_int to cpus_accel

  - rename CpusAccel functions from cpu_synchronize_* to synchronize_*

KNOWN ISSUES:

* hvf is currently impacted, because synchronize_state does not currently
  work like for the other accelerators. Probably we require an hvf working
  cpu_synchronize_state implementation before we can proceed.

OTHER MAIN OPEN POINTS:

* discussion pending on the name of the "cpus.c" module (also influencing
  other names) (Roman)

* naming of functions in cpus.c, should I push for more consistency and
  use the preample cpus_ more? (Roman)

* should we accept the larger overhead for each call of the kick and CPU
  sync state for all archs/accels of putting CpusAccel inside AccelClass?
  I would tend towards no here, but welcome further opinions or data if any.
  (Roman)

* should we reorder patches or moves inside patches to avoid code going
  from cpus.c to softmmu/cpus.c and then again to softmmu/somethingelse.c ?
  (Philippe)

* some questions about headers in include/softmmu (Philippe)



--------

v2 -> v3:

* turned into a 4 patch series, adding a first patch moving
  softmmu code currently in top_srcdir to softmmu/

* cpu-throttle: moved to softmmu/

* cpu-timers, icount:

  - moved to softmmu/

  - fixed assumption of qtest_enabled() => icount_enabled()
  causing the failure of check-qtest-arm goal, in test-arm-mptimer.c

  Fix is in hw/core/ptimer.c,

  where the artificial timeout rate limit should not be applied
  under qtest_enabled(), in a similar way to how it is not applied
  for icount_enabled().

* CpuAccelInterface: no change.


--------


v1 -> v2:

* 1/3 (cpu-throttle): provide a description in the commit message

* 2/3 (cpu-timers, icount): in this v2 separate icount from cpu-timers,
  as icount is actually TCG-specific. Only build it under CONFIG_TCG.

  To do this, qtest had to be detached from icount. To this end, a
  trivial global counter for qtest has been introduced.

* 3/3 (CpuAccelInterface): provided a description.

This is point 8) in that plan. The idea is to extract the unrelated parts
in cpus, and register interfaces from each single accelerator to the main
cpus module (cpus.c).

While doing this RFC, I noticed some assumptions about Windows being
either TCG or HAX (not considering WHPX) that might need to be revisited.
I added a comment there.

The thing builds successfully based on Linux cross-compilations for
windows/hax, windows/whpx, and I got a good build on Darwin/hvf.

Tests run successully for tcg and kvm configurations, but did not test on
windows or darwin.

Welcome your feedback and help on this,

Claudio

*** BLURB HERE ***

Claudio Fontana (4):
  softmmu: move softmmu only files from root
  cpu-throttle: new module, extracted from cpus.c
  cpu-timers, icount: new modules
  cpus: extract out accel-specific code to each accel

 MAINTAINERS                                  |   14 +-
 Makefile.target                              |    7 +-
 accel/kvm/Makefile.objs                      |    2 +
 accel/kvm/kvm-all.c                          |   15 +-
 accel/kvm/kvm-cpus-interface.c               |   94 ++
 accel/kvm/kvm-cpus-interface.h               |    8 +
 accel/qtest.c                                |   88 +-
 accel/stubs/kvm-stub.c                       |    3 +-
 accel/tcg/Makefile.objs                      |    1 +
 accel/tcg/cpu-exec.c                         |   43 +-
 accel/tcg/tcg-all.c                          |   19 +-
 accel/tcg/tcg-cpus-interface.c               |  523 ++++++
 accel/tcg/tcg-cpus-interface.h               |    8 +
 accel/tcg/translate-all.c                    |    3 +-
 cpus.c                                       | 2290 --------------------------
 docs/replay.txt                              |    6 +-
 exec.c                                       |    4 -
 hw/core/cpu.c                                |    1 +
 hw/core/ptimer.c                             |    6 +-
 hw/i386/x86.c                                |    1 +
 include/exec/cpu-all.h                       |    4 +
 include/exec/exec-all.h                      |    4 +-
 include/hw/core/cpu.h                        |   37 -
 include/qemu/main-loop.h                     |    5 +
 include/qemu/timer.h                         |   22 +-
 include/sysemu/cpu-throttle.h                |   50 +
 include/sysemu/cpu-timers.h                  |   72 +
 include/sysemu/cpus.h                        |   44 +-
 include/sysemu/hvf.h                         |    1 -
 include/sysemu/hw_accel.h                    |   57 +-
 include/sysemu/kvm.h                         |    2 +-
 include/sysemu/qtest.h                       |    2 +
 include/sysemu/replay.h                      |    4 +-
 migration/migration.c                        |    1 +
 migration/ram.c                              |    1 +
 replay/replay.c                              |    6 +-
 softmmu/Makefile.objs                        |   13 +
 arch_init.c => softmmu/arch_init.c           |    0
 balloon.c => softmmu/balloon.c               |    0
 softmmu/cpu-throttle.c                       |  122 ++
 softmmu/cpu-timers.c                         |  267 +++
 softmmu/cpus.c                               |  741 +++++++++
 softmmu/icount.c                             |  496 ++++++
 ioport.c => softmmu/ioport.c                 |    0
 memory.c => softmmu/memory.c                 |    0
 memory_mapping.c => softmmu/memory_mapping.c |    0
 qtest.c => softmmu/qtest.c                   |   34 +-
 softmmu/timers-state.h                       |   45 +
 softmmu/vl.c                                 |    8 +-
 stubs/Makefile.objs                          |    4 +-
 stubs/clock-warp.c                           |    4 +-
 stubs/cpu-get-clock.c                        |    3 +-
 stubs/cpu-get-icount.c                       |   21 -
 stubs/cpu-synchronize-state.c                |   15 +
 stubs/icount.c                               |   22 +
 stubs/qemu-timer-notify-cb.c                 |    8 +
 stubs/qtest.c                                |    5 +
 target/alpha/translate.c                     |    3 +-
 target/arm/helper.c                          |    7 +-
 target/i386/Makefile.objs                    |    7 +-
 target/i386/hax-all.c                        |    6 +-
 target/i386/hax-cpus-interface.c             |   85 +
 target/i386/hax-cpus-interface.h             |    8 +
 target/i386/hax-i386.h                       |    2 +
 target/i386/hax-posix.c                      |   12 +
 target/i386/hax-windows.c                    |   20 +
 target/i386/hvf/Makefile.objs                |    2 +-
 target/i386/hvf/hvf-cpus-interface.c         |   92 ++
 target/i386/hvf/hvf-cpus-interface.h         |    8 +
 target/i386/hvf/hvf.c                        |    5 +-
 target/i386/whpx-all.c                       |    3 +
 target/i386/whpx-cpus-interface.c            |   96 ++
 target/i386/whpx-cpus-interface.h            |    8 +
 target/riscv/csr.c                           |    8 +-
 tests/ptimer-test-stubs.c                    |    7 +-
 tests/test-timed-average.c                   |    2 +-
 util/main-loop.c                             |    4 +-
 util/qemu-timer.c                            |   12 +-
 78 files changed, 3136 insertions(+), 2517 deletions(-)
 create mode 100644 accel/kvm/kvm-cpus-interface.c
 create mode 100644 accel/kvm/kvm-cpus-interface.h
 create mode 100644 accel/tcg/tcg-cpus-interface.c
 create mode 100644 accel/tcg/tcg-cpus-interface.h
 delete mode 100644 cpus.c
 create mode 100644 include/sysemu/cpu-throttle.h
 create mode 100644 include/sysemu/cpu-timers.h
 rename arch_init.c => softmmu/arch_init.c (100%)
 rename balloon.c => softmmu/balloon.c (100%)
 create mode 100644 softmmu/cpu-throttle.c
 create mode 100644 softmmu/cpu-timers.c
 create mode 100644 softmmu/cpus.c
 create mode 100644 softmmu/icount.c
 rename ioport.c => softmmu/ioport.c (100%)
 rename memory.c => softmmu/memory.c (100%)
 rename memory_mapping.c => softmmu/memory_mapping.c (100%)
 rename qtest.c => softmmu/qtest.c (95%)
 create mode 100644 softmmu/timers-state.h
 delete mode 100644 stubs/cpu-get-icount.c
 create mode 100644 stubs/cpu-synchronize-state.c
 create mode 100644 stubs/icount.c
 create mode 100644 stubs/qemu-timer-notify-cb.c
 create mode 100644 target/i386/hax-cpus-interface.c
 create mode 100644 target/i386/hax-cpus-interface.h
 create mode 100644 target/i386/hvf/hvf-cpus-interface.c
 create mode 100644 target/i386/hvf/hvf-cpus-interface.h
 create mode 100644 target/i386/whpx-cpus-interface.c
 create mode 100644 target/i386/whpx-cpus-interface.h