Re: [PATCH v3 1/9] target/i386: Restrict X86CPUFeatureWord to X86 targets

[Markus Armbruster]

Philippe Mathieu-Daudé <address@hidden> writes:

> On 5/26/20 9:23 AM, Philippe Mathieu-Daudé wrote:
>> On 5/26/20 8:45 AM, Markus Armbruster wrote:
>>> Philippe Mathieu-Daudé <address@hidden> writes:
>>>
>>>> Move out x86-specific structures from generic machine code.
>>>>
>>>> Acked-by: Richard Henderson <address@hidden>
>>>> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
>>>> ---
>>>>  qapi/machine-target.json   | 45 ++++++++++++++++++++++++++++++++++++++
>>>>  qapi/machine.json          | 42 -----------------------------------
>>>>  target/i386/cpu.c          |  2 +-
>>>>  target/i386/machine-stub.c | 22 +++++++++++++++++++
>>>>  target/i386/Makefile.objs  |  3 ++-
>>>>  5 files changed, 70 insertions(+), 44 deletions(-)
>>>>  create mode 100644 target/i386/machine-stub.c
>>>>
>>>> diff --git a/qapi/machine-target.json b/qapi/machine-target.json
>>>> index f2c82949d8..fb7a4b7850 100644
>>>> --- a/qapi/machine-target.json
>>>> +++ b/qapi/machine-target.json
>>>> @@ -3,6 +3,51 @@
>>>>  # 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 ff7b5032e3..1fe31d374c 100644
>>>> --- a/qapi/machine.json
>>>> +++ b/qapi/machine.json
>>>> @@ -511,48 +511,6 @@
>>>>     '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 7a4a8e3847..832498c723 100644
>>>> --- a/target/i386/cpu.c
>>>> +++ b/target/i386/cpu.c
>>>> @@ -37,7 +37,7 @@
>>>>  #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/machine-stub.c b/target/i386/machine-stub.c
>>>> new file mode 100644
>>>> index 0000000000..cb301af057
>>>> --- /dev/null
>>>> +++ b/target/i386/machine-stub.c
>>>> @@ -0,0 +1,22 @@
>>>> +/*
>>>> + * QAPI x86 CPU features stub
>>>> + *
>>>> + * Copyright (c) 2020 Red Hat, Inc.
>>>> + *
>>>> + * Author:
>>>> + *   Philippe Mathieu-Daudé <address@hidden>
>>>> + *
>>>> + * 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"
>>>> +
>>>> +void visit_type_X86CPUFeatureWordInfoList(Visitor *v, const char *name,
>>>> +                                      X86CPUFeatureWordInfoList **obj,
>>>> +                                      Error **errp)
>>>
>>> Unusual indentation.
>>>
>>>> +{
>>>> +}
>>>
>>> Two kinds of stubs: stubs that can get called, and stubs that exist only
>>> to satisfy the linker.  Which kind is this one?
>> 
>> I suppose "stubs that exist only to satisfy the linker" must abort if
>> ever called...

Yes, and having such stubs can be okay.

> Link problem when building linux-user:
>
>   LINK    i386-linux-user/qemu-i386
> /usr/bin/ld: target/i386/cpu.o: in function `x86_cpu_get_feature_words':
> target/i386/cpu.c:4627: undefined reference to
> `visit_type_X86CPUFeatureWordInfoList'
> collect2: error: ld returned 1 exit status
> make[1]: *** [Makefile:208: qemu-i386] Error 1
> make: *** [Makefile:527: i386-linux-user/all] Error 2
>
> Various properties from x86_cpu_initfn() should be removed from
> user-mode (tsc/stepping/kvm/...) but I'll let that to some x86 specialist.

No objection.  Just tell me whether the stub is meant to be called,
because if it is, we need to consider what it should do when called.

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