Re: [PATCH 1/1] i386/cpu: Expose AVX_VNNI instruction to guset

[Yang Zhong]

Paolo, please help review this patch when you are not busy. 
The related kernel patch has been merged by you last time, thanks!

Regards,

Yang


On Mon, Mar 01, 2021 at 01:15:52PM +0800, Yang Zhong wrote:
> Expose AVX (VEX-encoded) versions of the Vector Neural Network
> Instructions to guest.
> 
> The bit definition:
> CPUID.(EAX=7,ECX=1):EAX[bit 4] AVX_VNNI
> 
> The following instructions are available when this feature is
> present in the guest.
>   1. VPDPBUS: Multiply and Add Unsigned and Signed Bytes
>   2. VPDPBUSDS: Multiply and Add Unsigned and Signed Bytes with Saturation
>   3. VPDPWSSD: Multiply and Add Signed Word Integers
>   4. VPDPWSSDS: Multiply and Add Signed Integers with Saturation
> 
> The release document ref below link:
> https://software.intel.com/content/www/us/en/develop/download/\
> intel-architecture-instruction-set-extensions-programming-reference.html
> 
> Signed-off-by: Yang Zhong <yang.zhong@intel.com>
> ---
>  target/i386/cpu.c | 4 ++--
>  target/i386/cpu.h | 2 ++
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 6a53446e6a..55545d8692 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -996,7 +996,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = 
> {
>          .type = CPUID_FEATURE_WORD,
>          .feat_names = {
>              NULL, NULL, NULL, NULL,
> -            NULL, "avx512-bf16", NULL, NULL,
> +            "avx-vnni", "avx512-bf16", NULL, NULL,
>              NULL, NULL, NULL, NULL,
>              NULL, NULL, NULL, NULL,
>              NULL, NULL, NULL, NULL,
> @@ -3273,7 +3273,7 @@ static X86CPUDefinition builtin_x86_defs[] = {
>              MSR_ARCH_CAP_SKIP_L1DFL_VMENTRY | MSR_ARCH_CAP_MDS_NO |
>              MSR_ARCH_CAP_PSCHANGE_MC_NO | MSR_ARCH_CAP_TAA_NO,
>          .features[FEAT_7_1_EAX] =
> -            CPUID_7_1_EAX_AVX512_BF16,
> +            CPUID_7_1_EAX_AVX_VNNI | CPUID_7_1_EAX_AVX512_BF16,
>          /*
>           * Missing: XSAVES (not supported by some Linux versions,
>           * including v4.1 to v4.12).
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 8be39cfb62..ef5f145626 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -803,6 +803,8 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS];
>  /* Speculative Store Bypass Disable */
>  #define CPUID_7_0_EDX_SPEC_CTRL_SSBD    (1U << 31)
>  
> +/* AVX VNNI Instruction */
> +#define CPUID_7_1_EAX_AVX_VNNI          (1U << 4)
>  /* AVX512 BFloat16 Instruction */
>  #define CPUID_7_1_EAX_AVX512_BF16       (1U << 5)
>  
> -- 
> 2.29.2.334.gfaefdd61ec