mbox series

[v2,0/7] target/arm: Remove TYPE_AARCH64_CPU class

Message ID 20250429132200.605611-1-peter.maydell@linaro.org
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Series target/arm: Remove TYPE_AARCH64_CPU class | expand

Message

Peter Maydell April 29, 2025, 1:21 p.m. UTC 
Currently we have a class hierarchy for Arm CPUs where
all the 32-bit CPUs (including M-profile) inherit directly
from TYPE_ARM_CPU, but the 64-bit CPUs inherit from
TYPE_AARCH64_CPU, which is a subclass of TYPE_ARM_CPU.
This subclass does essentially two things:
 * it sets up fields and methods for the gdbstub so that
   the gdbstub presents an AArch64 CPU to gdb rather than
   an AArch32 one
 * it defines the 'aarch64' CPU property which you can use
   with KVM to disable AArch64 and create a 32-bit VM
   (with "-cpu host,aarch64=off")

This is a bit weird, because the 32-bit CPU you create with
KVM and aarch64=off is still a subclass of TYPE_AARCH64_CPU.
It also still presents gdb with an AArch64 CPU, so you
effectively can't use the gdbstub with this kind of VM.

This patchseries removes TYPE_AARCH64_CPU so that all CPUs,
both AArch32 and AArch64, directly inherit from TYPE_ARM_CPU.
This lets us fix the bug with gdbstub and "aarch64=off".

In this version I fix the bug that Philippe found where we
were calling arm_gdbstub_is_aarch64() too early, before the
object had been created and the "is it AArch64 or not?"
question resolved. This is basically moving the gdb_init_cpu()
call into cpu_exec_realizefn(), but we need to do a little
adjustment of microblaze for that to work.

Version 2 of the patchset:
 * patches 1-5 from v1 are already upstream
 * new patches 1-3 here delay the call to gdb_init_cpu()
   so that it is done only after the CPU object is at least
   inited and we definitely know the final value of the
   'aarch64' property
 * patches 4-7 are the old 6-9 and have been reviewed

thanks
-- PMM

Peter Maydell (7):
  target/microblaze: Use 'obj' in DEVICE() casts in mb_cpu_initfn()
  target/microblaze: Delay gdb_register_coprocessor() to realize
  hw/core/cpu-common: Don't init gdbstub until cpu_exec_realizefn()
  target/arm: Present AArch64 gdbstub based on ARM_FEATURE_AARCH64
  target/arm: Move aarch64 CPU property code to TYPE_ARM_CPU
  target/arm/kvm: don't check TYPE_AARCH64_CPU
  target/arm: Remove TYPE_AARCH64_CPU

 target/arm/cpu-qom.h    |  5 ---
 target/arm/cpu.h        |  4 --
 target/arm/internals.h  |  3 +-
 hw/core/cpu-common.c    |  3 +-
 target/arm/cpu.c        | 36 ++++++++++++++++++
 target/arm/cpu64.c      | 82 +----------------------------------------
 target/arm/kvm.c        |  3 +-
 target/arm/tcg/cpu64.c  |  2 +-
 target/microblaze/cpu.c | 22 +++++------
 9 files changed, 52 insertions(+), 108 deletions(-)