On 3/25/20 8:46 AM, Paolo Bonzini wrote:
> On 25/03/20 16:30, Randy Dunlap wrote:
>> 24 (only showing one of them here) BUILD_BUG() errors in arch/x86/kvm/cpuid.h
>> function __cpuid_entry_get_reg(), for the default: case.
>>
>>
>> CC arch/x86/kvm/cpuid.o
>> In file included from ../include/linux/export.h:43:0,
>> from ../include/linux/linkage.h:7,
>> from ../include/linux/preempt.h:10,
>> from ../include/linux/hardirq.h:5,
>> from ../include/linux/kvm_host.h:7,
>> from ../arch/x86/kvm/cpuid.c:12:
>> In function ‘__cpuid_entry_get_reg’,
>> inlined from ‘kvm_cpu_cap_mask’ at ../arch/x86/kvm/cpuid.c:272:25,
>> inlined from ‘kvm_set_cpu_caps’ at ../arch/x86/kvm/cpuid.c:292:2:
>> ../include/linux/compiler.h:394:38: error: call to ‘__compiletime_assert_114’ declared with attribute error: BUILD_BUG failed
>> _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
>> ^
>> ../include/linux/compiler.h:375:4: note: in definition of macro ‘__compiletime_assert’
>> prefix ## suffix(); \
>> ^~~~~~
>> ../include/linux/compiler.h:394:2: note: in expansion of macro ‘_compiletime_assert’
>> _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
>> ^~~~~~~~~~~~~~~~~~~
>> ../include/linux/build_bug.h:39:37: note: in expansion of macro ‘compiletime_assert’
>> #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
>> ^~~~~~~~~~~~~~~~~~
>> ../include/linux/build_bug.h:59:21: note: in expansion of macro ‘BUILD_BUG_ON_MSG’
>> #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
>> ^~~~~~~~~~~~~~~~
>> ../arch/x86/kvm/cpuid.h:114:3: note: in expansion of macro ‘BUILD_BUG’
>> BUILD_BUG();
>> ^~~~~~~~~
>>
>
> Looks like the compiler is not smart enough to figure out the constant
> expressions in BUILD_BUG. I think we need to do something like this:
>
> diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
> index 23b4cd1ad986..8f711b0cdec0 100644
> --- a/arch/x86/kvm/cpuid.h
> +++ b/arch/x86/kvm/cpuid.h
> @@ -40,6 +40,7 @@ struct cpuid_reg {
> int reg;
> };
>
> +/* Update reverse_cpuid_check as well when adding an entry. */
> static const struct cpuid_reg reverse_cpuid[] = {
> [CPUID_1_EDX] = { 1, 0, CPUID_EDX},
> [CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX},
> @@ -68,12 +69,21 @@ static const struct cpuid_reg reverse_cpuid[] = {
> */
> static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
> {
> - BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
> - BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
> - BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
> - BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
> - BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
> - BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
> + BUILD_BUG_ON(x86_leaf != CPUID_1_EDX &&
> + x86_leaf != CPUID_8000_0001_EDX &&
> + x86_leaf != CPUID_8086_0001_EDX &&
> + x86_leaf != CPUID_1_ECX &&
> + x86_leaf != CPUID_C000_0001_EDX &&
> + x86_leaf != CPUID_8000_0001_ECX &&
> + x86_leaf != CPUID_7_0_EBX &&
> + x86_leaf != CPUID_D_1_EAX &&
> + x86_leaf != CPUID_8000_0008_EBX &&
> + x86_leaf != CPUID_6_EAX &&
> + x86_leaf != CPUID_8000_000A_EDX &&
> + x86_leaf != CPUID_7_ECX &&
> + x86_leaf != CPUID_8000_0007_EBX &&
> + x86_leaf != CPUID_7_EDX &&
> + x86_leaf != CPUID_7_1_EAX);
> }
>
> /*
>
> Randy, can you test it with your compiler?
Nope, no help. That's the wrong location.
Need a patch for this:
>> 24 (only showing one of them here) BUILD_BUG() errors in arch/x86/kvm/cpuid.h
>> function __cpuid_entry_get_reg(), for the default: case.
--
~Randy
