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

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Typo "guest" in subject.

On 4/6/21 3:57 AM, 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
> 
> As for the kvm related code, please reference Linux commit id 1085a6b585d7.
> 
> 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 6b3e9467f1..f0c48f06a2 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 570f916878..edc8984448 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -804,6 +804,8 @@ 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)
>  
>