Re: [Qemu-devel] [PATCH v1 00/15] Multi-Arch Phase 1

[Paolo Bonzini <pbonzini@redhat.com>]

On 11/09/2015 07:39, Peter Crosthwaite wrote:
> This is the first set of patches needed to enable Multi-arch system
> emulation. For full context refer to RFCv3:
> 
> [PATCH v3 00/35] Multi Architecture System Emulation
> https://lists.gnu.org/archive/html/qemu-devel/2015-07/msg03929.html
> 
> This is the first patch-pack intended for merge.
> 
> Original cover, as well as overall series state below for further
> information.

I think we can already merge patches 1, 3, 4, 5, 6, 11, 12, 13, 15
(plus, patch 10 is gone). The others do not make much sense without
multiarch support.

I suppose the next part of the surgery could be

  target-*: Don't redefine cpu_exec()
  target-*: cpu.h: Undefine core code symbols
  arm: cpu: static inline cpu_arm_init()
  target-arm: Split cp helper API to new C file
  hw: arm: Explicitly include cpu.h for consumers
  hw: mb: Explicitly include cpu.h for consumers

Paolo

> 
> Regards,
> Peter
> 
> Original Multi-arch arch patch series cover:
> 
> ***
> 
> This is target-multi, a system-mode build that can support multiple
> cpu-types.
> 
> Two architectures are initially converted. Microblaze and ARM. Step
> by step conversion in done for each. A microblaze is added to
> Xilinx Zynq platform as a test case. This will be elaborted more in
> future spins. This use case is valid, as Microblazes can be added (any
> number of them!) in Zynq FPGA programmable logic configuration.
> 
> The general approach (radically different to approach in V1 RFC) is to build
> and prelink an object (arch-obj.o) per-arch containing:
> 
> 1: target-foo/*
> 2: All uses of env internals and CPU_GET_ENV
>     * cputlb, translate-all, cpu-exec
>     * TCG backend
> 
> This means cputlb and friends are compiled multiple times fo each arch. The
> symbols for each of these pre-links are then localised to avoid link time name
> collisions. This is based on Paolo's suggestion to templatify cputlb and
> friends. Just the net of what to multi-compile is widened to include the TCG
> stuff as well now.
> 
> Despite being some "major surgery" this approach actually solves many of big
> the problems raised in V1. Big problems sovled:
> 
> 1: With the multi-compile TCG backends there are now multiple tcg_ctx's for
> each architecture. This solves the issue PMM raised WRT false positives on TB
> hashing as archs no longer share translation context.
> 
> 2: There is no longer a need to reorder the CPU_COMMON within the ENV or the ENV
> within the CPU. This was flagged as a performance issue by multiple people in
> V1.
> All users of the env internals as well as ENV_GET_CPU are now in multi-compile
> code and so multi-arch does not need to define a generic ENV nor does in need to
> def the problematic ENV_GET_CPU.
> 
> 3: With the prelink symbol localisation, link time namespace collision of
> helpers from multiple arches is no longer an issue. No need to bloat all the
> function names with arch specific prefixes.
> 
> 4: The architecture specifics used/defined by cpu-defs can now vary from arch to
> arch (incl. target_ulong) greatly reducing coversion effort needed. The list
> of restrictions for multi-arch capability is much reduced since V1. No
> target_long issues anymore.
> 
> include/exec/*.h and some of the common code needs some refactoring to setup
> this single vs multi compile split. Mostly code movements.
> 
> Some functions (like tcg_enabled) need to be listified for each of the
> now-multiple TCG engines.
> 
> The interface between the multi compile and single compiled files needs to be
> virtualised using QOM cpu functions. But this is now a very low footprint
> change as most of the virtualised hooks are now in mutli-compiled code (they
> only exist as text once). There are more new hooks than before, but the per
> target change pattern is reduced.
> 
> For the implementation of the series, the trickiest part is (still) cpu.h
> inclusion management. There are now more than one cpu.h's and different
> parts of the tree need a different include scheme. target-multi defines
> it's own cpu.h which is bare minimum defs as needed by core code only.
> target-foo/cpu.h are mostly the same but refactored to avoid collisions
> with other cpu.h's. Inclusion scheme goes something like
> this (for the multi-arch build):
> 
> *: Core code includes only target-multi/cpu.h
> *: target-foo/ implementation code includes target-foo/cpu.h locally
> *: System level code (e.g. mach models) can use multiple target-foo/cpu.h's
> 
> The hardest unasnwered Q is (still) what to do about bootloading. Currently
> each arch has it's own architecture specific bootloading which may assume a
> single architecture. I have applied some hacks to at least get this
> RFC testable using a -kernel -firmware split but going forward being
> able to associate an elf/image with a cpu explictitly needs to be
> solved.
> 
> No support for KVM, im not sure if a mix of TCG and KVM is supported even for
> a single arch? (which would be prerequisite to MA KVM).
> 
> ***
> 
> Current review state of full multi-arch work in progress branch:
> 
> cpu-exec: Migrate some generic fns to cpu-exec-common
> translate: Listify tcg_exec_init()                          R:rth
> translate-all: Move tcg_handle_interrupt() to -common       R:rth
> tcg: split tcg_op_defs to -common
> tcg: Move tcg_tb_ptr to -common
> translate: move real_host_page setting to -common
> cpus: Listify cpu_list() function
> translate-common: Listify tcg_enabled()
> core: Convert tcg_enabled() uses to any/all variants
> exec-all: Move cpu_can_do_io() to qom/cpu.h                 R:rth
> cputlb: move CPU_LOOP() for tlb_reset() to exec.c
> cputlb: Change tlb_set_dirty() arg to cpu
> include/exec: Move cputlb exec.c defs out                   R:rth
> cpu-common: Define tb_page_addr_t for everyone
> monitor: uninclude cpu_ldst
> disas: s390x: QOMify target specific disas setup            A:rth
> disas: moxie: QOMify target specific disas setup
> disas: m68k: QOMify target specific disas setup             R:laurentv R:gerg
> disas: sparc: QOMify target specific disas setup
> disas: lm32: QOMify target specific disas setup             A:mwalle
> disas: sh4: QOMify target specific disas setup              A:aurel
> disas: mips: QOMify target specific disas setup             A:lalrae
> disas: alpha: QOMify target specific disas setup            A:rth
> linux_user: elfload: Default ELF_MACHINE to ELF_ARCH        R:rth
> linux-user: elfload: Provide default for elf_check_arch     R:rth
> elf_ops: Fix coding style for EM alias case statement       R:rth
> elf: Update EM_MOXIE definition                             R:rth
> arm: Remove ELF_MACHINE from cpu.h                          R:rth
> mb: Remove ELF_MACHINE from cpu.h                           R:rth
> m68k: Remove ELF_MACHINE from cpu.h                         R:rth R:gerg R:laurentv
> cris: Remove ELF_MACHINE from cpu.h                         R:rth
> moxie: Remove ELF_MACHINE from cpu.h                        R:rth
> unicore: Remove ELF_MACHINE from cpu.h                      R:rth
> lm32: Remove ELF_MACHINE from cpu.h                         R:rth
> or32: Remove ELF_MACHINE from cpu.h                         R:rth
> tricore: Remove ELF_MACHINE from cpu.h                      R:rth
> xtensa: Remove ELF_MACHINE from cpu.h                       R:rth
> sh4: Remove ELF_MACHINE from cpu.h                          A:aurel R:rth
> s390: Remove ELF_MACHINE from cpu.h                         R:rth
> sparc: Remove ELF_MACHINE from cpu.h                        R:rth
> mips: Remove ELF_MACHINE from cpu.h                         R:aurel R:rth
> alpha: Remove ELF_MACHINE from cpu.h                        R:rth
> i386: Rename ELF_MACHINE to be x86 specific                 R:eduardo A:eduardo R:rth
> ppc: Rename ELF_MACHINE to be PPC specific                  R:rth
> arm: cpu: assert() on no-EL2 virt IRQ error condition.      R:pmm
> arm: Remove hw_error() usages.                              R:pmm
> configure: factor out adding disas configure                R:pmm
> target-*: Don't redefine cpu_exec()
> include/exec: Split target_long def to new header
> cpu-defs: Allow multiple inclusions
> target-*: cpu.h: Undefine core code symbols
> Makefile.target: Introduce arch-obj
> core: virtualise CPU interfaces completely
> core: Introduce multi-arch build
> arm: cpu: static inline cpu_arm_init()
> target-arm: Split cp helper API to new C file
> arm: register cpu_list() function
> arm: enable multi-arch
> hw: arm: Explicitly include cpu.h for consumers
> hw: mb: Explicitly include cpu.h for consumers
> microblaze: enable multi-arch
> arm: boot: Don't assume all CPUs are ARM
> arm: xilinx_zynq: Add a Microblaze
> HACK: mb: boot: Assume using -firmware for mb software
> HACK: mb: boot: Disable dtb load in multi-arch
> 
> 
> Peter Crosthwaite (15):
>   cpu-exec: Migrate some generic fns to cpu-exec-common
>   translate: Listify tcg_exec_init()
>   translate-all: Move tcg_handle_interrupt() to -common
>   tcg: split tcg_op_defs to -common
>   tcg: Move tcg_tb_ptr to -common
>   translate: move real_host_page setting to -common
>   cpus: Listify cpu_list() function
>   translate-common: Listify tcg_enabled()
>   core: Convert tcg_enabled() uses to any/all variants
>   exec-all: Move cpu_can_do_io() to qom/cpu.h
>   cputlb: move CPU_LOOP() for tlb_reset() to exec.c
>   cputlb: Change tlb_set_dirty() arg to cpu
>   include/exec: Move cputlb exec.c defs out
>   cpu-common: Define tb_page_addr_t for everyone
>   monitor: uninclude cpu_ldst
> 
>  Makefile.target           |   3 ++
>  cpu-exec-common.c         | 108 ++++++++++++++++++++++++++++++++++++++
>  cpu-exec.c                |  49 -----------------
>  cpus.c                    |  10 +---
>  cputlb.c                  |  30 +++++------
>  exec.c                    |  13 ++---
>  include/exec/cpu-common.h |   4 ++
>  include/exec/cputlb.h     |  16 ------
>  include/exec/exec-all.h   |  20 ++++++-
>  include/exec/ram_addr.h   |   5 +-
>  include/qemu-common.h     |   6 +++
>  include/qom/cpu.h         |  22 ++++++++
>  include/sysemu/cpus.h     |   7 +++
>  memory.c                  |   8 +--
>  monitor.c                 |   1 -
>  tcg/tcg-common.c          |  35 +++++++++++++
>  tcg/tcg.c                 |   8 +--
>  tcg/tci/tcg-target.c      |   2 +-
>  tci.c                     |   6 ---
>  translate-all.c           |  46 ++++------------
>  translate-common.c        | 130 ++++++++++++++++++++++++++++++++++++++++++++++
>  21 files changed, 375 insertions(+), 154 deletions(-)
>  create mode 100644 cpu-exec-common.c
>  create mode 100644 tcg/tcg-common.c
>  create mode 100644 translate-common.c
>