Re: [PATCH v8 46/55] i386/tdx: Add supported CPUID bits related to TD Attributes

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 5/6/2025 7:31 PM, Zhao Liu wrote:
> On Tue, Apr 01, 2025 at 09:01:56AM -0400, Xiaoyao Li wrote:
>> Date: Tue,  1 Apr 2025 09:01:56 -0400
>> From: Xiaoyao Li <xiaoyao.li@intel.com>
>> Subject: [PATCH v8 46/55] i386/tdx: Add supported CPUID bits related to TD
>>   Attributes
>> X-Mailer: git-send-email 2.34.1
>>
>> For TDX, some CPUID feature bit is configured via TD attributes. They
>> are not covered by tdx_caps.cpuid (which only contians the configurable
>> bits), but they are actually supported when the related attributre bit
>> is supported.
>>
>> Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
>> ---
>>   target/i386/cpu.h     |  4 +++
>>   target/i386/kvm/tdx.c | 59 +++++++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 63 insertions(+)
>>
>> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
>> index 115137279a1a..0e984ec42bb6 100644
>> --- a/target/i386/cpu.h
>> +++ b/target/i386/cpu.h
>> @@ -903,6 +903,8 @@ uint64_t x86_cpu_get_supported_feature_word(X86CPU *cpu, FeatureWord w);
>>   #define CPUID_7_0_ECX_LA57              (1U << 16)
>>   /* Read Processor ID */
>>   #define CPUID_7_0_ECX_RDPID             (1U << 22)
>> +/* KeyLocker */
>> +#define CPUID_7_0_ECX_KeyLocker         (1U << 23)
>>   /* Bus Lock Debug Exception */
>>   #define CPUID_7_0_ECX_BUS_LOCK_DETECT   (1U << 24)
>>   /* Cache Line Demote Instruction */
>> @@ -963,6 +965,8 @@ uint64_t x86_cpu_get_supported_feature_word(X86CPU *cpu, FeatureWord w);
>>   #define CPUID_7_1_EAX_AVX_VNNI          (1U << 4)
>>   /* AVX512 BFloat16 Instruction */
>>   #define CPUID_7_1_EAX_AVX512_BF16       (1U << 5)
>> +/* Linear address space separation */
>> +#define CPUID_7_1_EAX_LASS              (1U << 6)
>>   /* CMPCCXADD Instructions */
>>   #define CPUID_7_1_EAX_CMPCCXADD         (1U << 7)
>>   /* Fast Zero REP MOVS */
> 
> The whole framework is very good for me.
> 
> Since LASS/key locker are not yet supported, I think it's better to add
> the note (in the commit message or code) that they are helpful for
> future enabling. Of course, removing these two features would be best,
> as they cannot be covered by current testing.

I will add note in the commit message and don't change the code.

Keep them in tdx_attrs_maps[] is helpful for the completeness of the 
existing attribute bits that are related to a CPUID feature.

> Regards,
> Zhao
> 
>