Re: [PATCH v2 2/3] x86/cpufeatures: Add CPU feature flags for Zhaoxin Hash Engine

["H. Peter Anvin" <hpa@zytor.com>]

On January 23, 2024 1:44:27 AM PST, Borislav Petkov <bp@alien8.de> wrote:
>On Tue, Jan 23, 2024 at 10:28:51AM +0800, Tony W Wang-oc wrote:
>> Zhaoxin CPUs have implemented the SHA(Secure Hash Algorithm) as its
>> instrucions.
>> Add two CPU feature flags indicated by CPUID.(EAX=C0000001,ECX=0):EDX
>> bit 25/26 which will be used by Zhaoxin SHA driver.
>> 
>> Signed-off-by: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
>> ---
>>  arch/x86/include/asm/cpufeatures.h       | 4 +++-
>>  tools/arch/x86/include/asm/cpufeatures.h | 4 +++-
>>  2 files changed, 6 insertions(+), 2 deletions(-)
>> 
>> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
>> index 29cb275a219d..28b0e62dbdf5 100644
>> --- a/arch/x86/include/asm/cpufeatures.h
>> +++ b/arch/x86/include/asm/cpufeatures.h
>> @@ -145,7 +145,7 @@
>>  #define X86_FEATURE_RDRAND		( 4*32+30) /* RDRAND instruction */
>>  #define X86_FEATURE_HYPERVISOR		( 4*32+31) /* Running on a hypervisor */
>>  
>> -/* VIA/Cyrix/Centaur-defined CPU features, CPUID level 0xC0000001, word 5 */
>> +/* VIA/Cyrix/Centaur/Zhaoxin-defined CPU features, CPUID level 0xC0000001, word 5 */
>
>Does that mean that all those companies agree on the contents of this
>CPUID leaf?
>
>>  #define X86_FEATURE_XSTORE		( 5*32+ 2) /* "rng" RNG present (xstore) */
>>  #define X86_FEATURE_XSTORE_EN		( 5*32+ 3) /* "rng_en" RNG enabled */
>>  #define X86_FEATURE_XCRYPT		( 5*32+ 6) /* "ace" on-CPU crypto (xcrypt) */
>> @@ -156,6 +156,8 @@
>>  #define X86_FEATURE_PHE_EN		( 5*32+11) /* PHE enabled */
>>  #define X86_FEATURE_PMM			( 5*32+12) /* PadLock Montgomery Multiplier */
>>  #define X86_FEATURE_PMM_EN		( 5*32+13) /* PMM enabled */
>> +#define X86_FEATURE_PHE2		( 5*32+25) /* "phe2" Zhaoxin Hash Engine */
>> +#define X86_FEATURE_PHE2_EN		( 5*32+26) /* "phe2_en" PHE2 enabled */
>						      ^^^^^^^^^
>
>From: Documentation/arch/x86/cpuinfo.rst
>
>"a: Feature flags can be derived from the contents of CPUID leaves.
>------------------------------------------------------------------
>These feature definitions are organized mirroring the layout of CPUID
>leaves and grouped in words with offsets as mapped in enum cpuid_leafs
>in cpufeatures.h (see arch/x86/include/asm/cpufeatures.h for details).
>If a feature is defined with a X86_FEATURE_<name> definition in
>cpufeatures.h, and if it is detected at run time, the flags will be
>displayed accordingly in /proc/cpuinfo. For example, the flag "avx2"
>comes from X86_FEATURE_AVX2 in cpufeatures.h."
>
>Is your grep broken?
>

Well, Centaur bought Cyrix, and then VIA bought Centaur. I think Zhaoxin is a joint venture between VIA and the City of Shanghai, or something like that?