Re: [RFC v7 00/22] i386 cleanup [hw/core/cpu.c common]

[Claudio Fontana]

On 11/30/20 3:35 AM, Claudio Fontana wrote:
> Hi all, this is v7 of the i386 cleanup,

This is fairly broken still and I am fixing it up,

but a question arises while hunting bugs here.

Silent bugs are introduced when trying to use code like

#ifndef CONFIG_USER_ONLY

in files that are built in "common" objects, since they are target independent.

I wonder also about the rationale why the cpu code is split between

hw/core/cpu.c and $(top_srcdir)/cpu.c

with one part in common and one part in "target specific".

What do we gain by having part of the cpu in common?

In some cases we end up going through all sort of hoops because we cannot just 
code everything in hw/core/cpu.c due to the fact
that we do not see CONFIG_ there.


> with the most interesting patches at the end.
> 
> v6 -> v7: integrate TCGCpuOperations, refactored cpu_exec_realizefn
> 
> * integrate TCGCpuOperations (Eduardo)
> 
> Taken some refactoring from Eduardo for Tcg-only operations on
> CPUClass.
> 
> * refactored cpu_exec_realizefn
> 
> The other main change is a refactoring of cpu_exec_realizefn,
> directly linked to the effort of making many cpu_exec operations
> TCG-only (Eduardo series above):
> 
> cpu_exec_realizefn is actually a TCG-only thing, with the
> exception of a couple things that can be done in base cpu code.
> 
> This changes all targets realizefn, so I guess I have to Cc:
> the Multiverse? (Universe was already CCed for all accelerators).
> 
> 
> v5 -> v6: remove MODULE_INIT_ACCEL_CPU
> 
> 
> instead, use a call to accel_init_interfaces().
> 
> * The class lookups are now general and performed in accel/
> 
>   new AccelCPUClass for new archs are supported as new
>   ones appear in the class hierarchy, no need for stubs.
> 
> * Split the code a bit better
> 
> 
> v4 -> v5: centralized and simplified initializations
> 
> I put in Cc: Emilio G. Cota, specifically because in patch 8
> I (re)moved for user-mode the call to tcg_regions_init().
> 
> The call happens now inside the tcg AccelClass machine_init,
> (so earlier). This seems to work fine, but thought to get the
> author opinion on this.
> 
> Rebased on "tcg-cpus: split into 3 tcg variants" series
> (queued by Richard), to avoid some code churn:
> 
> 
> https://lists.gnu.org/archive/html/qemu-devel/2020-10/msg04356.html
> 
> 
> * Extended AccelClass to user-mode.
> 
> user-mode now does not call tcg_exec_init directly,
> instead it uses the tcg accel class, and its init_machine method.
> 
> Since user-mode does not define or use a machine state,
> the machine is just passed as NULL.
> 
> The immediate advantage is that now we can call current_accel()
> from both user mode and softmmu, so we can work out the correct
> class to use for accelerator initializations.
> 
> * QOMification of CpusAccelOps
> 
> simple QOMification of CpusAccelOps abstract class.
> 
> * Centralized all accel_cpu_init, so only one per cpu-arch,
>   plus one for all accels will remain.
> 
>   So we can expect accel_cpu_init() to be limited to:
>   
>   softmmu/cpus.c - initializes the chosen softmmu accel ops for the cpus 
> module.
>   target/ARCH/cpu.c - initializes the chosen arch-specific cpu accelerator.
>   
> These changes are meant to address concerns/issues (Paolo):
> 
> 1) the use of if (tcg_enabled()) and similar in the module_init call path
> 
> 2) the excessive number of accel_cpu_init() to hunt down in the codebase.
> 
> 
> * Fixed wrong use of host_cpu_class_init (Eduardo)
> 
> 
> v3 -> v4: QOMification of X86CPUAccelClass
> 
> 
> In this version I basically QOMified X86CPUAccel, taking the
> suggestions from Eduardo as the starting point,
> but stopping just short of making it an actual QOM interface,
> using a plain abstract class, and then subclasses for the
> actual objects.
> 
> Initialization is still using the existing qemu initialization
> framework (module_call_init), which is I still think is better
> than the alternatives proposed, in the current state.
> 
> Possibly some improvements could be developed in the future here.
> In this case, effort should be put in keeping things extendible,
> in order not to be blocked once accelerators also become modules.
> 
> Motivation and higher level steps:
> 
> https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg04628.html
> 
> Looking forward to your comments on this proposal,
> 
> Ciao,
> 
> Claudio
> 
> Claudio Fontana (13):
>   i386: move kvm accel files into kvm/
>   i386: move whpx accel files into whpx/
>   i386: move hax accel files into hax/
>   i386: hvf: remove stale MAINTAINERS entry for old hvf stubs
>   i386: move TCG accel files into tcg/
>   i386: move cpu dump out of helper.c into cpu-dump.c
>   i386: move TCG cpu class initialization out of helper.c
>   accel: extend AccelState and AccelClass to user-mode
>   accel: replace struct CpusAccel with AccelOpsClass
>   accel: introduce AccelCPUClass extending CPUClass
>   i386: split cpu accelerators from cpu.c, using AccelCPUClass
>   cpu-exec: refactor realizefn for all targets
>   cpu: introduce cpu_accel_instance_init
> 
> Eduardo Habkost (9):
>   tcg: cpu_exec_{enter,exit} helpers
>   tcg: make CPUClass.cpu_exec_* optional
>   tcg: Make CPUClass.debug_excp_handler optional
>   cpu: Remove unnecessary noop methods
>   cpu: Introduce TCGCpuOperations struct
>   cpu: Move synchronize_from_tb() to tcg_ops
>   cpu: Move cpu_exec_* to tcg_ops
>   cpu: Move tlb_fill to tcg_ops
>   cpu: Move debug_excp_handler to tcg_ops
> 
>  MAINTAINERS                           |  19 +-
>  accel/accel-common.c                  | 105 +++++
>  accel/{accel.c => accel-softmmu.c}    |  60 +--
>  accel/accel-softmmu.h                 |  15 +
>  accel/accel-user.c                    |  24 ++
>  accel/kvm/kvm-all.c                   |   2 -
>  accel/kvm/kvm-cpus.c                  |  26 +-
>  accel/kvm/kvm-cpus.h                  |   2 -
>  accel/meson.build                     |   4 +-
>  accel/qtest/qtest.c                   |  25 +-
>  accel/tcg/cpu-exec.c                  |  86 +++-
>  accel/tcg/cputlb.c                    |   6 +-
>  accel/tcg/meson.build                 |   2 +-
>  accel/tcg/tcg-all.c                   |  11 +-
>  accel/tcg/tcg-cpus-icount.c           |  11 +-
>  accel/tcg/tcg-cpus-icount.h           |   2 +
>  accel/tcg/tcg-cpus-mttcg.c            |  12 +-
>  accel/tcg/tcg-cpus-mttcg.h            |  19 +
>  accel/tcg/tcg-cpus-rr.c               |   7 -
>  accel/tcg/tcg-cpus.c                  |  43 ++
>  accel/tcg/tcg-cpus.h                  |   4 -
>  accel/tcg/user-exec.c                 |   6 +-
>  accel/xen/xen-all.c                   |  24 +-
>  bsd-user/main.c                       |  12 +-
>  cpu.c                                 |  53 +--
>  hw/core/cpu.c                         |  44 ++-
>  hw/i386/fw_cfg.c                      |   2 +-
>  hw/i386/intel_iommu.c                 |   2 +-
>  hw/i386/kvm/apic.c                    |   2 +-
>  hw/i386/kvm/clock.c                   |   2 +-
>  hw/i386/microvm.c                     |   2 +-
>  hw/i386/pc.c                          |   2 +-
>  hw/i386/pc_piix.c                     |   1 +
>  hw/i386/x86.c                         |   2 +-
>  include/exec/cpu-all.h                |   4 +
>  include/hw/boards.h                   |   2 +-
>  include/hw/core/accel-cpu.h           |  25 ++
>  include/hw/core/cpu.h                 |  65 ++--
>  include/hw/core/tcg-cpu-ops.h         |  56 +++
>  include/{sysemu => qemu}/accel.h      |  16 +-
>  include/sysemu/accel-ops.h            |  45 +++
>  include/sysemu/cpus.h                 |  26 +-
>  include/sysemu/hvf.h                  |   2 +-
>  include/sysemu/kvm.h                  |   2 +-
>  include/sysemu/kvm_int.h              |   2 +-
>  linux-user/main.c                     |   8 +-
>  meson.build                           |   1 +
>  softmmu/cpus.c                        |  12 +-
>  softmmu/memory.c                      |   2 +-
>  softmmu/qtest.c                       |   2 +-
>  softmmu/vl.c                          |  12 +-
>  target/alpha/cpu.c                    |  12 +-
>  target/arm/cpu.c                      |  16 +-
>  target/arm/cpu64.c                    |   2 +-
>  target/arm/cpu_tcg.c                  |   2 +-
>  target/avr/cpu.c                      |  13 +-
>  target/cris/cpu.c                     |  20 +-
>  target/hppa/cpu.c                     |  11 +-
>  target/i386/cpu-dump.c                | 538 +++++++++++++++++++++++++
>  target/i386/cpu.c                     | 418 ++------------------
>  target/i386/cpu.h                     | 120 +-----
>  target/i386/{ => hax}/hax-all.c       |   5 +-
>  target/i386/{ => hax}/hax-cpus.c      |  29 +-
>  target/i386/{ => hax}/hax-cpus.h      |   2 -
>  target/i386/{ => hax}/hax-i386.h      |   6 +-
>  target/i386/{ => hax}/hax-interface.h |   0
>  target/i386/{ => hax}/hax-mem.c       |   0
>  target/i386/{ => hax}/hax-posix.c     |   0
>  target/i386/{ => hax}/hax-posix.h     |   0
>  target/i386/{ => hax}/hax-windows.c   |   0
>  target/i386/{ => hax}/hax-windows.h   |   0
>  target/i386/hax/meson.build           |   7 +
>  target/i386/helper-tcg.h              | 112 ++++++
>  target/i386/helper.c                  | 539 +-------------------------
>  target/i386/host-cpu.c                | 198 ++++++++++
>  target/i386/host-cpu.h                |  19 +
>  target/i386/hvf/cpu.c                 |  65 ++++
>  target/i386/hvf/hvf-cpus.c            |  27 +-
>  target/i386/hvf/hvf-cpus.h            |   2 -
>  target/i386/hvf/hvf-i386.h            |   2 +-
>  target/i386/hvf/hvf.c                 |   3 +-
>  target/i386/hvf/meson.build           |   1 +
>  target/i386/hvf/x86_task.c            |   2 +-
>  target/i386/kvm/cpu.c                 | 148 +++++++
>  target/i386/{ => kvm}/hyperv-proto.h  |   0
>  target/i386/{ => kvm}/hyperv-stub.c   |   0
>  target/i386/{ => kvm}/hyperv.c        |   0
>  target/i386/{ => kvm}/hyperv.h        |   0
>  target/i386/kvm/kvm-cpu.h             |  41 ++
>  target/i386/{ => kvm}/kvm-stub.c      |   0
>  target/i386/{ => kvm}/kvm.c           |   3 +-
>  target/i386/{ => kvm}/kvm_i386.h      |   0
>  target/i386/kvm/meson.build           |   8 +
>  target/i386/kvm/trace-events          |   7 +
>  target/i386/kvm/trace.h               |   1 +
>  target/i386/machine.c                 |   4 +-
>  target/i386/meson.build               |  39 +-
>  target/i386/{ => tcg}/bpt_helper.c    |   1 +
>  target/i386/{ => tcg}/cc_helper.c     |   1 +
>  target/i386/tcg/cpu.c                 | 173 +++++++++
>  target/i386/{ => tcg}/excp_helper.c   |   1 +
>  target/i386/{ => tcg}/fpu_helper.c    |  33 +-
>  target/i386/{ => tcg}/int_helper.c    |   1 +
>  target/i386/{ => tcg}/mem_helper.c    |   1 +
>  target/i386/tcg/meson.build           |  14 +
>  target/i386/{ => tcg}/misc_helper.c   |   1 +
>  target/i386/{ => tcg}/mpx_helper.c    |   1 +
>  target/i386/{ => tcg}/seg_helper.c    |   1 +
>  target/i386/{ => tcg}/smm_helper.c    |   2 +
>  target/i386/{ => tcg}/svm_helper.c    |   1 +
>  target/i386/{ => tcg}/tcg-stub.c      |   0
>  target/i386/{ => tcg}/translate.c     |   1 +
>  target/i386/trace-events              |   6 -
>  target/i386/whpx/meson.build          |   4 +
>  target/i386/{ => whpx}/whp-dispatch.h |   0
>  target/i386/{ => whpx}/whpx-all.c     |   4 +-
>  target/i386/{ => whpx}/whpx-cpus.c    |  29 +-
>  target/i386/{ => whpx}/whpx-cpus.h    |   2 -
>  target/lm32/cpu.c                     |  13 +-
>  target/m68k/cpu.c                     |  10 +-
>  target/microblaze/cpu.c               |  17 +-
>  target/mips/cpu.c                     |  12 +-
>  target/moxie/cpu.c                    |  10 +-
>  target/nios2/cpu.c                    |  12 +-
>  target/openrisc/cpu.c                 |  12 +-
>  target/ppc/translate_init.c.inc       |  17 +-
>  target/riscv/cpu.c                    |  18 +-
>  target/rx/cpu.c                       |  18 +-
>  target/s390x/cpu.c                    |  13 +-
>  target/sh4/cpu.c                      |  12 +-
>  target/sparc/cpu.c                    |  14 +-
>  target/tilegx/cpu.c                   |  10 +-
>  target/tricore/cpu.c                  |  10 +-
>  target/unicore32/cpu.c                |  12 +-
>  target/xtensa/cpu.c                   |  12 +-
>  135 files changed, 2302 insertions(+), 1540 deletions(-)
>  create mode 100644 accel/accel-common.c
>  rename accel/{accel.c => accel-softmmu.c} (64%)
>  create mode 100644 accel/accel-softmmu.h
>  create mode 100644 accel/accel-user.c
>  create mode 100644 accel/tcg/tcg-cpus-mttcg.h
>  create mode 100644 include/hw/core/accel-cpu.h
>  create mode 100644 include/hw/core/tcg-cpu-ops.h
>  rename include/{sysemu => qemu}/accel.h (94%)
>  create mode 100644 include/sysemu/accel-ops.h
>  create mode 100644 target/i386/cpu-dump.c
>  rename target/i386/{ => hax}/hax-all.c (99%)
>  rename target/i386/{ => hax}/hax-cpus.c (71%)
>  rename target/i386/{ => hax}/hax-cpus.h (95%)
>  rename target/i386/{ => hax}/hax-i386.h (95%)
>  rename target/i386/{ => hax}/hax-interface.h (100%)
>  rename target/i386/{ => hax}/hax-mem.c (100%)
>  rename target/i386/{ => hax}/hax-posix.c (100%)
>  rename target/i386/{ => hax}/hax-posix.h (100%)
>  rename target/i386/{ => hax}/hax-windows.c (100%)
>  rename target/i386/{ => hax}/hax-windows.h (100%)
>  create mode 100644 target/i386/hax/meson.build
>  create mode 100644 target/i386/helper-tcg.h
>  create mode 100644 target/i386/host-cpu.c
>  create mode 100644 target/i386/host-cpu.h
>  create mode 100644 target/i386/hvf/cpu.c
>  create mode 100644 target/i386/kvm/cpu.c
>  rename target/i386/{ => kvm}/hyperv-proto.h (100%)
>  rename target/i386/{ => kvm}/hyperv-stub.c (100%)
>  rename target/i386/{ => kvm}/hyperv.c (100%)
>  rename target/i386/{ => kvm}/hyperv.h (100%)
>  create mode 100644 target/i386/kvm/kvm-cpu.h
>  rename target/i386/{ => kvm}/kvm-stub.c (100%)
>  rename target/i386/{ => kvm}/kvm.c (99%)
>  rename target/i386/{ => kvm}/kvm_i386.h (100%)
>  create mode 100644 target/i386/kvm/meson.build
>  create mode 100644 target/i386/kvm/trace-events
>  create mode 100644 target/i386/kvm/trace.h
>  rename target/i386/{ => tcg}/bpt_helper.c (99%)
>  rename target/i386/{ => tcg}/cc_helper.c (99%)
>  create mode 100644 target/i386/tcg/cpu.c
>  rename target/i386/{ => tcg}/excp_helper.c (99%)
>  rename target/i386/{ => tcg}/fpu_helper.c (99%)
>  rename target/i386/{ => tcg}/int_helper.c (99%)
>  rename target/i386/{ => tcg}/mem_helper.c (99%)
>  create mode 100644 target/i386/tcg/meson.build
>  rename target/i386/{ => tcg}/misc_helper.c (99%)
>  rename target/i386/{ => tcg}/mpx_helper.c (99%)
>  rename target/i386/{ => tcg}/seg_helper.c (99%)
>  rename target/i386/{ => tcg}/smm_helper.c (99%)
>  rename target/i386/{ => tcg}/svm_helper.c (99%)
>  rename target/i386/{ => tcg}/tcg-stub.c (100%)
>  rename target/i386/{ => tcg}/translate.c (99%)
>  create mode 100644 target/i386/whpx/meson.build
>  rename target/i386/{ => whpx}/whp-dispatch.h (100%)
>  rename target/i386/{ => whpx}/whpx-all.c (99%)
>  rename target/i386/{ => whpx}/whpx-cpus.c (73%)
>  rename target/i386/{ => whpx}/whpx-cpus.h (96%)
>