Re: [PATCH v3 10/11] target/i386: Restrict X86CPUFeatureWord to X86 targets

[Eduardo Habkost <ehabkost@redhat.com>]

On Wed, Sep 30, 2020 at 06:49:48PM +0200, Philippe Mathieu-Daudé wrote:
> Only qemu-system-FOO and qemu-storage-daemon provide QMP
> monitors, therefore such declarations and definitions are
> irrelevant for user-mode emulation.
> 
> Restricting the x86-specific commands to machine-target.json
> pulls less QAPI-generated code into user-mode.
> 
> Add a stub to satisfy linking in user-mode:
> 
>   /usr/bin/ld: libqemu-i386-linux-user.fa.p/target_i386_cpu.c.o: in function `x86_cpu_get_feature_words':
>   target/i386/cpu.c:4643: undefined reference to `visit_type_X86CPUFeatureWordInfoList'
>   collect2: error: ld returned 1 exit status
>   make: *** [Makefile.ninja:1125: qemu-i386] Error 1
> 

If you don't want the QAPI definitions in user mode, there's no
reason to register the properties in user mode.  Wrapping #ifdef
around "feature-words" and "filtered-features" registration would
be simpler than adding a stub.

> Acked-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> v3: Reworded + Meson rebase
> ---
>  qapi/machine-target.json   | 45 ++++++++++++++++++++++++++++++++++++++
>  qapi/machine.json          | 42 -----------------------------------
>  target/i386/cpu.c          |  2 +-
>  target/i386/feature-stub.c | 23 +++++++++++++++++++
>  target/i386/meson.build    |  1 +
>  5 files changed, 70 insertions(+), 43 deletions(-)
>  create mode 100644 target/i386/feature-stub.c
> 
> diff --git a/qapi/machine-target.json b/qapi/machine-target.json
> index 698850cc78..b4d769a53b 100644
> --- a/qapi/machine-target.json
> +++ b/qapi/machine-target.json
> @@ -4,6 +4,51 @@
>  # This work is licensed under the terms of the GNU GPL, version 2 or later.
>  # See the COPYING file in the top-level directory.
>  
> +##
> +# @X86CPURegister32:
> +#
> +# A X86 32-bit register
> +#
> +# Since: 1.5
> +##
> +{ 'enum': 'X86CPURegister32',
> +  'data': [ 'EAX', 'EBX', 'ECX', 'EDX', 'ESP', 'EBP', 'ESI', 'EDI' ],
> +  'if': 'defined(TARGET_I386)' }
> +
> +##
> +# @X86CPUFeatureWordInfo:
> +#
> +# Information about a X86 CPU feature word
> +#
> +# @cpuid-input-eax: Input EAX value for CPUID instruction for that feature word
> +#
> +# @cpuid-input-ecx: Input ECX value for CPUID instruction for that
> +#                   feature word
> +#
> +# @cpuid-register: Output register containing the feature bits
> +#
> +# @features: value of output register, containing the feature bits
> +#
> +# Since: 1.5
> +##
> +{ 'struct': 'X86CPUFeatureWordInfo',
> +  'data': { 'cpuid-input-eax': 'int',
> +            '*cpuid-input-ecx': 'int',
> +            'cpuid-register': 'X86CPURegister32',
> +            'features': 'int' },
> +  'if': 'defined(TARGET_I386)' }
> +
> +##
> +# @DummyForceArrays:
> +#
> +# Not used by QMP; hack to let us use X86CPUFeatureWordInfoList internally
> +#
> +# Since: 2.5
> +##
> +{ 'struct': 'DummyForceArrays',
> +  'data': { 'unused': ['X86CPUFeatureWordInfo'] },
> +  'if': 'defined(TARGET_I386)' }
> +
>  ##
>  # @CpuModelInfo:
>  #
> diff --git a/qapi/machine.json b/qapi/machine.json
> index 72f014bb5b..cb878acdac 100644
> --- a/qapi/machine.json
> +++ b/qapi/machine.json
> @@ -544,48 +544,6 @@
>     'dst': 'uint16',
>     'val': 'uint8' }}
>  
> -##
> -# @X86CPURegister32:
> -#
> -# A X86 32-bit register
> -#
> -# Since: 1.5
> -##
> -{ 'enum': 'X86CPURegister32',
> -  'data': [ 'EAX', 'EBX', 'ECX', 'EDX', 'ESP', 'EBP', 'ESI', 'EDI' ] }
> -
> -##
> -# @X86CPUFeatureWordInfo:
> -#
> -# Information about a X86 CPU feature word
> -#
> -# @cpuid-input-eax: Input EAX value for CPUID instruction for that feature word
> -#
> -# @cpuid-input-ecx: Input ECX value for CPUID instruction for that
> -#                   feature word
> -#
> -# @cpuid-register: Output register containing the feature bits
> -#
> -# @features: value of output register, containing the feature bits
> -#
> -# Since: 1.5
> -##
> -{ 'struct': 'X86CPUFeatureWordInfo',
> -  'data': { 'cpuid-input-eax': 'int',
> -            '*cpuid-input-ecx': 'int',
> -            'cpuid-register': 'X86CPURegister32',
> -            'features': 'int' } }
> -
> -##
> -# @DummyForceArrays:
> -#
> -# Not used by QMP; hack to let us use X86CPUFeatureWordInfoList internally
> -#
> -# Since: 2.5
> -##
> -{ 'struct': 'DummyForceArrays',
> -  'data': { 'unused': ['X86CPUFeatureWordInfo'] } }
> -
>  ##
>  # @NumaCpuOptions:
>  #
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 3ffd877dd5..d45fa217cc 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -38,7 +38,7 @@
>  #include "qemu/option.h"
>  #include "qemu/config-file.h"
>  #include "qapi/error.h"
> -#include "qapi/qapi-visit-machine.h"
> +#include "qapi/qapi-visit-machine-target.h"
>  #include "qapi/qapi-visit-run-state.h"
>  #include "qapi/qmp/qdict.h"
>  #include "qapi/qmp/qerror.h"
> diff --git a/target/i386/feature-stub.c b/target/i386/feature-stub.c
> new file mode 100644
> index 0000000000..787c3c7fa1
> --- /dev/null
> +++ b/target/i386/feature-stub.c
> @@ -0,0 +1,23 @@
> +/*
> + * QAPI x86 CPU features stub
> + *
> + * Copyright (c) 2020 Red Hat, Inc.
> + *
> + * Author:
> + *   Philippe Mathieu-Daudé <philmd@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "qapi/qapi-visit-machine-target.h"
> +
> +bool visit_type_X86CPUFeatureWordInfoList(Visitor *v, const char *name,
> +                                          X86CPUFeatureWordInfoList **obj,
> +                                          Error **errp)
> +{
> +    g_assert_not_reached();
> +}
> diff --git a/target/i386/meson.build b/target/i386/meson.build
> index e0b71ade56..0c5d9e6caf 100644
> --- a/target/i386/meson.build
> +++ b/target/i386/meson.build
> @@ -5,6 +5,7 @@ i386_ss.add(files(
>    'helper.c',
>    'xsave_helper.c',
>  ))
> +i386_ss.add(when: 'CONFIG_SOFTMMU', if_false: files('feature-stub.c'))
>  i386_ss.add(when: 'CONFIG_TCG', if_true: files(
>    'bpt_helper.c',
>    'cc_helper.c',
> -- 
> 2.26.2
> 
> 

-- 
Eduardo