Re: [RFC PATCH v4 2/3] target/i386: Restrict system-specific features from user emulation

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 12/9/23 16:05, Paolo Bonzini wrote:
> On 9/11/23 23:13, Philippe Mathieu-Daudé wrote:
>>   /*
>>    * Only for builtin_x86_defs models initialized with 
>> x86_register_cpudef_types.
>>    */
>> @@ -6163,6 +6195,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t 
>> index, uint32_t count,
>>               }
>>               *edx = env->features[FEAT_7_0_EDX]; /* Feature flags */
>> +#ifndef CONFIG_USER_ONLY
>>               /*
>>                * SGX cannot be emulated in software.  If hardware does 
>> not
>>                * support enabling SGX and/or SGX flexible launch control,
>> @@ -6181,6 +6214,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t 
>> index, uint32_t count,
>>                       CPUID_7_0_ECX_SGX_LC))) {
>>                   *ecx &= ~CPUID_7_0_ECX_SGX_LC;
>>               }
>> +#endif
> 
> This can use a variant of x86_cpu_get_supported_cpuid that returns a 
> single register; or it can be rewritten to use x86_cpu_get_supported_cpuid.

Great suggestion, thanks!

> In general, a lot of checks for accel_uses_host_cpuid() are unnecessary, 
> and the code can be modified to not depend on either KVM or HVF.

OK.