[PATCH 00/22] target/riscv: declarative CPU definitions

[Paolo Bonzini <pbonzini@redhat.com>]

Hi Alastair,

the subject is a slightly underhanded description, in that what I really
wanted to achieve was removing RISC-V's use of .instance_post_init; that's
because RISC-V operate with an opposite conception of .instance_post_init
compared to everyone else: RISC-V wants to register properties there,
whereas x86 and hw/pci-bridge/pcie_root_port.c want to set them.
While it's possible to move RISC-V's code to instance_init, the others
have to run after global properties have been set by device_post_init().

However, I think the result is an improvement anyway, in that it makes
CPU definitions entirely declarative.  Previously, multiple instance_init
functions each override the properties that were set by the superclass,
and the code used a mix of subclassing and direct invocation of other
functions.  Now, instead, after .class_init all the settings for each
model are available in a RISCVCPUDef struct, and the result is copied
into the RISCVCPU at .instance_init time.  This is done with a single
function that starts from the parent's RISCVCPUDef and applies the delta
stored in the CPU's class_data.

Apart from the small reduction in line count, one advantage is that
more validation of the models can be done unconditionally at startup,
instead of happening dynamically if a CPU model is chosen.

Tested by running query-cpu-model-expansion on all concrete models,
before and after applying the patches, with no change except the bugfix
noted in patch 10.  The 64-bit variant of the script is as follows:

  for i in \
    "max" "max32" "rv32" "rv64" "x-rv128" "rv32i" "rv32e" "rv64i" "rv64e" \
    "rva22u64" "rva22s64" "lowrisc-ibex" "shakti-c" "sifive-e31" "sifive-e34" \
    "sifive-e51" "sifive-u34" "sifive-u54" "thead-c906" "veyron-v1" \
    "tt-ascalon" "xiangshan-nanhu"
  do
  echo $i
  echo "
  {'execute': 'qmp_capabilities'}
  {'execute': 'query-cpu-model-expansion', 'arguments':{'type': 'full', 'model': {'name': '$i'}}}
  {'execute': 'quit'}
  " | ./qemu-system-riscv64 -qmp stdio -display none -M none | jq .return.model > list-new/$i
  echo "
  {'execute': 'qmp_capabilities'}
  {'execute': 'query-cpu-model-expansion', 'arguments':{'type': 'full', 'model': {'name': '$i'}}}
  {'execute': 'quit'}
  " | ../../qemu-rust/+build/qemu-system-riscv64 -qmp stdio -display none -M none | jq .return.model > list-old/$i
  done

Do you think this is a good approach?

Paolo

Paolo Bonzini (22):
  target/riscv: remove unused macro DEFINE_CPU
  target/riscv: introduce RISCVCPUDef
  target/riscv: store RISCVCPUDef struct directly in the class
  target/riscv: merge riscv_cpu_class_init with the class_base function
  target/riscv: move RISCVCPUConfig fields to a header file
  target/riscv: add more RISCVCPUDef fields
  target/riscv: convert abstract CPU classes to RISCVCPUDef
  target/riscv: convert profile CPU models to RISCVCPUDef
  target/riscv: convert bare CPU models to RISCVCPUDef
  target/riscv: move 128-bit check to TCG realize
  target/riscv: convert dynamic CPU models to RISCVCPUDef
  target/riscv: convert SiFive E CPU models to RISCVCPUDef
  target/riscv: convert ibex CPU models to RISCVCPUDef
  target/riscv: convert SiFive U models to RISCVCPUDef
  target/riscv: th: make CSR insertion test a bit more intuitive
  target/riscv: generalize custom CSR functionality
  target/riscv: convert TT C906 to RISCVCPUDef
  target/riscv: convert TT Ascalon to RISCVCPUDef
  target/riscv: convert Ventana V1 to RISCVCPUDef
  target/riscv: convert Xiangshan Nanhu to RISCVCPUDef
  target/riscv: remove .instance_post_init
  target/riscv: move SATP modes out of CPUConfig

 target/riscv/cpu-qom.h            |   2 +
 target/riscv/cpu.h                |  43 +-
 target/riscv/cpu_cfg.h            | 175 +-----
 target/riscv/cpu_cfg_fields.h.inc | 163 +++++
 hw/riscv/boot.c                   |   2 +-
 hw/riscv/virt-acpi-build.c        |   6 +-
 hw/riscv/virt.c                   |   4 +-
 target/riscv/cpu.c                | 967 ++++++++++++++----------------
 target/riscv/csr.c                |   2 +-
 target/riscv/gdbstub.c            |   6 +-
 target/riscv/kvm/kvm-cpu.c        |  21 +-
 target/riscv/machine.c            |   2 +-
 target/riscv/tcg/tcg-cpu.c        |  19 +-
 target/riscv/th_csr.c             |  30 +-
 target/riscv/translate.c          |   2 +-
 15 files changed, 689 insertions(+), 755 deletions(-)
 create mode 100644 target/riscv/cpu_cfg_fields.h.inc

-- 
2.48.1